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Context Recap / DoctorWho2017CSTwiceUponATime

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1[[WMG:[[center:[-''[[Series/DoctorWho Doctor Who]]'' [[Recap/DoctorWho recap index]]\
2'''Twelfth Doctor Era'''\
3'''Series 10:''' [[Recap/DoctorWho2016CSTheReturnOfDoctorMysterio CS]] | [[Recap/DoctorWhoS36E1ThePilot 1]] | [[Recap/DoctorWhoS36E2Smile 2]] | [[Recap/DoctorWhoS36E3ThinIce 3]] | [[Recap/DoctorWhoS36E4KnockKnock 4]] | [[Recap/DoctorWhoS36E5Oxygen 5]] | [[Recap/DoctorWhoS36E6Extremis 6]] | [[Recap/DoctorWhoS36E7ThePyramidAtTheEndOfTheWorld 7]] | [[Recap/DoctorWhoS36E8TheLieOfTheLand 8]] | [[Recap/DoctorWhoS36E9EmpressOfMars 9]] | [[Recap/DoctorWhoS36E10TheEatersOfLight 10]] | [[Recap/DoctorWhoS36E11WorldEnoughAndTime 11]] | [[Recap/DoctorWhoS36E12TheDoctorFalls 12]] | '''CS'''\
4'''[[Recap/DoctorWhoS35E1TheMagiciansApprentice <<< Series 9]]''' | '''[[Recap/DoctorWhoS37E1TheWomanWhoFellToEarth Series 11 >>>]]''']]-]]]
5!Twice Upon a Time
6[[quoteright:350:https://static.tvtropes.org/pmwiki/pub/images/dw_1014_twice_upon_a_time_9.jpg]]
7[[caption-width-right:350:''[[WhoWantsToLiveForever "Can't I ever have peace? Can't I rest?"]]''[[note]]From left to right: [[Creator/PearlMackie Bill Potts]], The TARDIS, [[Creator/PeterCapaldi the Doctor]] and [[Creator/DavidBradley the Doctor]]. Not pictured: [[Creator/MarkGatiss A captain]] and [[Creator/JodieWhittaker the Doctor]].[[/note]]]]
8[[caption-width-right:350:[[labelnote:Click here to see the RadioTimes magazine poster for this episode:]] https://static.tvtropes.org/pmwiki/pub/images/doctorwhotwiceuponatimeposter.jpg[softreturn]''"What happens now, where I go now, it has be alone."'']][[/labelnote]]
9->Written by Creator/StevenMoffat and Creator/ChrisChibnall[[note]]Uncredited[[/note]]\
10Directed by Creator/RachelTalalay\
11'''Air date:''' 25 December 2017
12
13->'''Twelfth Doctor:''' Why are you trying not to regenerate?\
14'''First Doctor:''' I have the courage and the right to live and die as myself.\
15'''Twelfth Doctor:''' Too late, it's started. A few minutes ago, you were weak as a kitten, right? Now you're fine. We're in a state of grace, both of us, but it won't last long. We have a choice. Either we change and go on, or we die as we are.
16
17JustForFun/{{The one w|ith}}here [[Creator/PeterCapaldi Twelve]] plus [[Creator/DavidBradley One]] equals [[Creator/JodieWhittaker Thirteen]].
18
19----
20
21''"OnceUponATime, the Doctor refused to regenerate... twice."''
22
23"[[PreviouslyOn Previously on]] ''Doctor Who''... [[Recap/DoctorWhoS4E2TheTenthPlanet 709 episodes ago]]", the [[Characters/DoctorWhoFirstDoctor First Doctor]] was in the midst of a confrontation with a bizarre new race of cyborgs, the [[Characters/DoctorWhoCybermen Cybermen]] of Mondas, at an Antarctic military base and his old body was wearing a bit thin. Realizing he would soon be regenerating and terrified of what this would mean for his future, he wandered off into the Antarctic snow, far from his companions Ben and Polly.
24
25Previously on ''Doctor Who''... [[Recap/DoctorWhoS36E12TheDoctorFalls one episode ago]], [[Main/TheNthDoctor thirteen lives]] [[Main/LongRunners and]] [[Recap/DoctorWho2013CSTheTimeOfTheDoctor a new regeneration cycle later]], the [[Characters/DoctorWhoTwelfthDoctor Twelfth Doctor]] stumbled out into the Antarctic wastes and barely managed to put off his regeneration yet again. He had been barely saved from his final death in a battle with the Cybermen on a gigantic Mondasian colony ship, knowing Nardole would be looking after the colonists who were taken to safety. But he also believed his beloved companion Bill Potts to have died in a HeroicSacrifice as one of those Cybermen. ''And'' his childhood friend turned nemesis and fellow Time Lady [[Characters/DoctorWhoMissy Missy]] ([[Characters/DoctorWhoMasters the Master]]) seems to have forsaken a HeelFaceTurn after he spent decades trying to rehabilitate her. At this point, the Doctor was tired of changing — tired of life itself. After everything he's gone through in this incarnation, Twelve has hit his breaking point and just wants to die permanently. So the TARDIS brought him to this familiar snowy waste to prove a point...
26
27And thus these two Doctors cross paths. And then time freezes, a British army captain (Creator/MarkGatiss) from [[UsefulNotes/WorldWarI the First World War]] appears in their midst, and a mysterious Glass Woman appears after that...
28
29The Glass Woman is part of the Testimony, a mysterious construct that is kidnapping humans throughout time and space — taking them in the final moment of their lives to download their memories before returning them to their fates, and capable of creating avatars of these people from said memories. The Captain is just one of their latest subjects, and the Testimony insists on returning him to his proper time and death. The Doctors have something to say about all this kidnapping and are determined to figure out what the Testimony's grand design is; accompanied by an avatar of Bill Potts herself, they and the Captain escape to find answers.
30
31Is there really hope for the Captain? Is a person truly the sum of their memories? What will it take to convince the original Doctor to embrace a future that will be marked by violence and sorrow? What will it take to convince his later self to keep going after that future has become the past? And with all the lessons they learned in this life, [[Characters/DoctorWhoThirteenthDoctor what kind of person]] will the Twelfth Doctor become after this adventure?
32
33----
34
35The 2017 Christmas special is the EndOfAnAge in many ways. Out of several milestones, this episode serves as:
36
37* Moffat's final ''Doctor Who'' script and final work as showrunner after eight years (until Series 14's "[[Recap/DoctorWhoS40E3Boom Boom]]" six and a half years later), with Creator/ChrisChibnall taking over for Series 11 to Series 13.
38* The final episode to be composed by Music/MurrayGold until 2023, with him having been the series composer since the revival in 2005. He would be succeeded by Segun Akinola from 2018 to 2022.
39* The final episode of the trilogy which started with "[[Recap/DoctorWhoS36E11WorldEnoughAndTime World Enough and Time]]" and "[[Recap/DoctorWhoS36E12TheDoctorFalls The Doctor Falls]]".
40* The final episode for the Twelfth Doctor (Creator/PeterCapaldi) and the first episode for the Thirteenth Doctor (Creator/JodieWhittaker), which also makes it the first regeneration of the Doctor that involves a gender change.
41* The first multi-Doctor episode since "[[Recap/DoctorWho50thASTheDayOfTheDoctor The Day of the Doctor]]", featuring Creator/DavidBradley as the First Doctor.
42* The first full-length multi-Doctor special (and the first of any length since the mini-episode "[[Recap/DoctorWho2007CiNSTimeCrash Time Crash]]") to team up an original series Doctor with a revival-era one onscreen;
43* The first time in the revival era -- and only the second time ''ever'' -- that a previously-seen [[TheNthDoctor incarnation of the Doctor]] has been played by a [[TheOtherDarrin replacement actor]] in a major, episode-long appearance, with David Bradley replacing the deceased Richard Hurndall from "[[Recap/DoctorWho20thASTheFiveDoctors The Five Doctors]]" after Hurndall himself replaced the ''first'' First Doctor, the deceased Creator/WilliamHartnell, for ''that'' one-off multi-Doctor story, giving One the odd distinction of being played by more actors than any other Doctor onscreen (the runner up being Six, played by both Creator/ColinBaker and a {{Fake Shemp}}-ing Creator/SylvesterMcCoy).
44* The second time the classic 1963-style TARDIS interior design appears in the revival era, after a slightly smaller version appeared in "[[Recap/DoctorWhoS35E12HellBent Hell Bent]]".
45* The final appearance of the "neon" console room, which was first seen in 2012's "[[Recap/DoctorWho2012CSTheSnowmen The Snowmen]]" and was slightly remodeled in 2014's "[[Recap/DoctorWhoS34E1DeepBreath Deep Breath]]". It is also the final appearance of the external TARDIS police box prop in use since 2010's "[[Recap/DoctorWhoS31E1TheEleventhHour The Eleventh Hour]]".
46* The last ChristmasEpisode of the revival era for six years (until 2023's "[[Recap/DoctorWho2023CSTheChurchOnRubyRoad The Church on Ruby Road]]"), as during the Creator/ChrisChibnall era the annual holiday special was aired on New Year's Day instead.
47
48Previews: [[https://www.youtube.com/watch?v=YCkDXegqjR0 Trailer 1]], [[https://www.youtube.com/watch?v=zr-oow9TxzU "Children in Need" Preview Clip]], [[https://www.youtube.com/watch?v=Xzpm8hyq6yM Trailer 2]].
49
50----
51!!Tropes:
52
53* ThirteenIsUnlucky: The Thirteenth Doctor starts her debut with a real doozy of a CliffHanger.
54* TheAirNotThere: When time freezes, the falling snowflakes halt in place, but the invisible air molecules don't appear to since the Doctors and the Captain are able to move around and breathe without any problems.
55* AllThereInTheManual:
56** WordOfGod stated the Captain to be the Brigadier's grandfather. According to Henry Lincoln and the Haisman estate (who own the character and publish the spin-off ''Lethbridge-Stewart'' series), the Captain was the Brig's great-uncle, and his brother Alastair is the Brigadier's grandfather. A compromise was agreed upon to solve the conflict, in the form of [[http://mailchi.mp/6a0db744bb65/hs7hix02oj-2836461 a free story]] which establishes, or at least strongly (and deliberately) implies, that the Captain is, in fact, both the Brigadier's great-uncle and his ''biological'' grandfather.
57** Paul Cornell's {{Novelization}} more clearly explains Bill Potts's fate and why her glass avatar cannot tell the Doctor what happened after Heather arrived: The Testimony edits Glass!Bill's memories so she can interact with the Twelfth Doctor as she did up until they separated on Floor 507, rather than have their interactions affected by spoilers. Glass!Bill does have all her memories restored later, after Testimony decides the Doctor is trustworthy: Bill and Heather, after spending time exploring the universe, went back to Earth to live as humans and grew old together. This relationship was so happy that Bill ultimately chose to die as a human, but on her deathbed told Heather she was free to return to her Pilot form if she wanted, and she did. This also easily fills in any WhatHappenedToTheMouse details regarding Bill's adoptive mum and other people in her life. The 2020 short "The Best of Times" (written by Moffat) adds more details about Bill's post-televised life; circa 2020 she and Heather are temporarily estranged due to the relationship difficulties that come with the latter having become bit of a know-it-all during the time she was more Pilot than human.
58** The {{Novelization}} and "The Best of Times" reveal Nardole too got a SurprisinglyHappyEnding post-"The Doctor Falls": The former specifies that he lived to '''728''' as the leader of the solar farmers, successfully handling several additional Cybermen advances until all they had to deal with were "Cybermats every spring", and ending up married six times ("two of them at once"). Moreover, the Testimony ''was'' going to send him back when they realized he wasn't human, but he convinced/guilted them into letting his memories be harvested!
59** The novelization ''also'' states the ring the Twelfth Doctor wears from the denouement of "[[Recap/DoctorWhoS34E1DeepBreath Deep Breath]]" to the moment of his regeneration into Thirteen is "his wedding ring", representing his relationship with River Song, whom he informally married in the Series 6 finale and previous incarnation. In fact, Twelve's relationship with River factors into why he would rather not regenerate: Having known something akin to human, romantic love with her (she's the key reason he'd rather not have One see the browser history!) and borne her loss makes him feel like he's lived a truly full life. When he decides to keep living, he also accepts that he can't stay as he is because of that feeling -- (s)he needs to desire ''more'' again.
60** The {{Novelization}} also heavily suggests that the First Doctor's sexist remarks were made in jest solely to annoy the Twelfth Doctor. First doesn't seem to express such beliefs when talking to Bill on her own in the episode, backing this up somewhat.
61* AndStarring:
62** The billing of Creator/PearlMackie is presented this way in the first trailer.
63** In the episode proper, it's David Bradley who gets the "and" in the intro. The credits, naturally, end with "And introducing Jodie Whittaker as the Doctor."
64* ArmorPiercingQuestion: Bill gets in a decent one when she asks why the Doctor left Gallifrey, enough to make the First Doctor stop and think:
65-->'''Bill:''' I don't mean what you ran away from. What were you running to?\
66'''First Doctor:''' That's rather a good question.\
67'''Bill:''' Questions are kinda my thing. How are you with answers?
68* AstonishinglyAppropriateInterruption
69-->'''Captain:''' But it's so... [BiggerOnTheInside]\
70'''First Doctor:''' Hideous!
71* ArsonMurderAndJaywalking: "Never be cruel. Never be cowardly. And never, ever eat pears!"
72* BackForTheFinale:
73** Pearl Mackie returns as Bill Potts... more specifically the ''memories'' of Bill Potts, which are really the sum of a person anyway.
74** Rusty the Dalek makes a very unexpected comeback.
75** Near the end of the episode, avatars of Clara and Nardole also briefly show up.
76** In a meta sense too, Murray Gold revisits many of his iconic pieces before stepping down as series composer. The Ninth Doctor's theme (commonly called the "Bad Wolf" theme and officially labeled "The Doctor's Theme"), "All the Strange, Strange Creatures" from the Tenth Doctor's era, the eponymous "[[Recap/DoctorWhoS28E13Doomsday Doomsday]]" theme, the Eleventh Doctor's theme "I Am the Doctor"/"The Majestic Tale", the Twelfth Doctor's theme "A Good Man?", and "The Shepherd's Boy" from "[[Recap/DoctorWhoS35E11HeavenSent Heaven Sent]]" all make appearances here, alongside several other pieces that are subtlely strung out across the episode.
77* BackToTheEarlyInstalment: The special begins with footage from ''The Tenth Planet'' which then morphs into a recreation with David Bradley reenacting William Hartnell's portrayal of the First Doctor's last few scenes.
78* BadassBoast: The First Doctor is rather bemused by Twelve doing this, as he's tipping off his opponent of his intentions before he carries them out.
79* BadassInDistress:
80** The Twelfth Doctor is still dressed in his singed and torn clothes from his battle with his Cybermen, and his hair is a mess. More importantly, he's also actively trying to fight off his regeneration.
81** The episode ends with the Thirteenth Doctor literally tossed out of the TARDIS and cast into freefall.
82* BeingGoodSucks:
83** The First Doctor admits that he's baffled by how the universe maintains the BalanceBetweenGoodAndEvil, and that evil ought to triumph constantly. Good requires things like loyalty, self-sacrifice and love, and is generally not a practical survival strategy.
84** The ''Twelfth'' Doctor, upon agreeing with the TARDIS that the universe ''does'' still need him, decides that regenerating into his next life and soldiering on won't kill anybody... except, of course, [[LossOfIdentity this particular incarnation]].
85* BerserkButton: Rusty tries to kill the Doctor for calling him a "good Dalek", once again replying that the Doctor is a much better one.
86* BigBad: The Doctor initially believes Testimony to be this but [[GoodAllAlong turns out to be mistaken]].
87* BiggerOnTheInside: [[SharePhrase But of course.]] The Captain, this time. Once again, of course, the Doctor is expecting this:
88-->'''Twelve:''' [[DeadpanSnarker You know, I thought it probably was. Glad it's not just me.]]
89* BilingualBonus: The German soldier whom the Captain regretfully faces down, pistol to pistol, is ''also'' saying he doesn't want to kill his counterpart and pleading for Lethbridge-Stewart to just leave him there.
90* {{Bookends}}:
91** The running trend continues as another incarnation of the Doctor dies as he was born: on Christmas.
92** Steven Moffat's tenure began with a Doctor who initially believed he had become a girl after his regeneration. Now, his tenure ends with the Doctor becoming a woman for real.
93** The first shot we ever see of the Twelfth Doctor in "[[Recap/DoctorWho50thASTheDayOfTheDoctor The Day of the Doctor]]" is a closeup of his eyes, with fierce determination. The last shot we ever see of the Twelfth Doctor is his eyes, softened, relenting.
94** In [[Recap/DoctorWho2013CSTheTimeOfTheDoctor The Time of the Doctor]], one of the first things Twelve feels is pain in his kidneys. Here, one of the last things he feels is the same thing.
95** In Twelve's first episode, "[[Recap/DoctorWhoS34E1DeepBreath Deep Breath]]", he felt hurt and rejected when Clara initially wouldn't recognize him as a new regeneration of "her" Doctor. In his last episode, it's Bill who feels that way when ''Twelve'' is reluctant to accept her as a legitimate manifestation of his young friend.
96** The First Doctor's first scene in the episode starts with original footage from "[[Recap/DoctorWhoS4E2TheTenthPlanet The Tenth Planet]]" with William Hartnell's performance, before transitioning into a recreation of the scene with David Bradley. His final scene begins with David Bradley setting the scene, before transitioning back into the original footage with Hartnell for the actual regeneration sequence.
97** [[Recap/DoctorWhoS30E17E18TheEndOfTime As one showrunner leaves]], the Doctor's regeneration is violent enough to wreck the interior of their predecessor's control room and the new incarnation, in the tattered clothes of their former self, [[Recap/DoctorWhoS31E1TheEleventhHour ends up clinging on for dear life as the doors of the ship are knocked open and they nearly fall out]]. Except for one thing: Thirteen ''really'' falls out while Eleven managed to pull himself back in.
98** One for Moffat's onscreen tenure as a writer: As in "[[Recap/DoctorWhoS27E9TheEmptyChild The Empty Child]]"/"[[Recap/DoctorWhoS27E10TheDoctorDances The Doctor Dances]]", EverybodyLives — even though some must regenerate to do so.
99*** Also, both episodes feature a largely benevolent antagonist whose villainous actions are largely accidental, in the nanogenes, and the testimony.
100** A throwaway reference in Moffat's [[Recap/DoctorWhoS27E10TheDoctorDances first story written for the show]] to the weapon-factories of Villengard pays off ''twelve years later'', as we finally get to see what Villengard looks like.
101** At the end of the [[Recap/DoctorWhoS36E12TheDoctorFalls previous episode]], the Doctor tells himself to "let it go" as he starts to regenerate, refusing to change despite his own survival instinct. At the end of this one, he tells his current self, "I let you go," as he accepts the change that's coming at last.
102** On a similar note, Moffat's run [[Recap/DoctorWhoS30E17E18TheEndOfTime began]] and ends on the heels of perfectly contrasting last words and a whole lot of CharacterDevelopment in between:
103--->'''Ten:''' I don't want to go.\
104'''Twelve:''' Doctor... I let you go.
105** Murray Gold's final episode (at the time) concludes with the Ninth Doctor's theme, which he created for Series 1, playing during the Thirteenth Doctor's first scene.
106* BothSidesHaveAPoint: The Twelfth Doctor refuses to consider that Bill is the real Bill while she insists that she's the real deal. While it isn't Bill "in the flesh", proving the Doctor correct, it is the sum of her memories (and by implication, personality as well), which proves Bill right.
107* BorrowedCatchphrase: After Twelve accidentally lets on that it is only the First World War (implying there will be more) he has to console the Captain with his wife's line of "Spoilers".
108* BrainUploading: The Testimony does this with humans' memories and by extension personalities and can download them into Glass People avatars.
109* BrickJoke:
110** In the 2005 episode "[[Recap/DoctorWhoS27E10TheDoctorDances The Doctor Dances]]", the Doctor mentions how he visited the weapon-factories of Villengard once, but they were destroyed (presumably because of him). In this episode, his twelfth incarnation finally travels back to Villengard, bringing things full circle.
111** Internal to the episode, the First Doctor finds the brandy stash in Twelve’s TARDIS, noting that some of it has gone missing. When he returns to his own stash and pours some of the version there, he notes [[StableTimeLoop “So that’s where it went.”]]
112* TheBusCameBack:
113** As this story takes place during the events of "[[Recap/DoctorWhoS4E2TheTenthPlanet The Tenth Planet]]" for the First Doctor, Polly and Ben appear with him as TheCameo in the opening sequence. Later, the interior of his TARDIS as well as the 1966 exterior police box design appear in larger "roles".
114** Rusty, the "good" Dalek in "[[Recap/DoctorWhoS34E2IntoTheDalek Into the Dalek]]" returns, having spent the intervening billions of years killing other Daleks who came to exterminate him. He also seems to despise the Doctor for making him into what he is and also tries to exterminate him as well (at first).
115* CallBack:
116** The Twelfth Doctor declares the Earth as being under his protection once more (as each of the new series Doctors have done at least once since the Tenth Doctor in "[[Recap/DoctorWho2005CSTheChristmasInvasion The Christmas Invasion]]") — much to his original self's confusion, as he doesn't think of himself as holding such duty.
117** One to Creator/StevenMoffat's first story for the Revival, as this story visits the ruins of Villengard, which was mentioned all the way back in 2005's "[[Recap/DoctorWhoS27E9TheEmptyChild The Empty Child]]"/"[[Recap/DoctorWhoS27E10TheDoctorDances The Doctor Dances]]". Oddly enough, [[ArsonMurderAndJaywalking there's no banana grove]]. Was Nine joking all along?
118** [[Recap/DoctorWhoS2E2TheDalekInvasionOfEarth The First Doctor threatens Bill with a smacked bottom.]]
119** [[Recap/DoctorWhoS12E2TheArkInSpace The Doctor keeps brandy in the TARDIS.]] Which explains where [[Recap/DoctorWho2015CSTheHusbandsOfRiverSong River got it from]].
120** Bill laments that she's standing right in front of the Doctor and he can't see that she's real, [[IronicEcho echoing back]] to [[Recap/DoctorWhoS34E1DeepBreath Twelve's first episode]] when he complained the same thing of Clara who couldn't reconcile him as being the same Doctor she'd known.
121** In "[[Recap/DoctorWhoS32E4TheDoctorsWife The Doctor's Wife]]", the TARDIS tells the Doctor she takes him where he ''needs'' to go, not where he ''wants'' to go. Here, she deliberately takes him to where his First Doctor is about to regenerate, rather than some quiet place to die for real. In the novelization, Twelve even explains the TARDIS's way of thinking to One in a direct reference to this episode.
122** The Twelfth Doctor again [[Recap/DoctorWhoS36E4KnockKnock likens regeneration to a big lunch]].
123** When the First Doctor is about to regenerate, a bit of "Vale Decem", [[Recap/DoctorWhoS30E17E18TheEndOfTime the music that heralded the Tenth Doctor's departure,]] plays.
124** As the glass replicas of Bill and Nardole hug the Doctor together, [[Recap/DoctorWhoS36E5Oxygen Nardole says "cuddle"]].
125** Oh, look, the Doctor [[Recap/DoctorWhoS30E17E18TheEndOfTime held back his regeneration until the last possible second again]] and now the TARDIS has [[Recap/DoctorWhoS31E1TheEleventhHour been blasted all to hell and is falling out of the sky]]. Well, actually, ''the Doctor'' is the one falling out of the sky, this time. The TARDIS itself tosses her out and then dematerializes, mid-fireball.
126** The {{Novelization}} adds even more call backs, including the Doctors recalling their old teacher Borusa's wisdom "In hope you are at your weakest, [[BewareTheSuperman in strength you are at your worst]]." Twelve realizes all of his lives beyond his first often forget the second part to their ultimate sorrow, and it has "become the most reliable part of his character." Twelve, embarrassed, ruefully notes that Borusa was ultimately a {{Hypocrite}} given his actions in "[[Recap/DoctorWho20thASTheFiveDoctors The Five Doctors]]". This exchange takes place shortly after the Testimony has revealed the grim side of the First Doctor's future lives to him, which in the book includes nods to the tragic ending of "[[Recap/DoctorWhoS30E16TheWatersOfMars The Waters of Mars]]" and the fates of Adric (killed), Donna Noble (LaserGuidedAmnesia and resultant loss of CharacterDevelopment), and Bill Potts (Cyber-converted — though she got better of course). And Rusty comments to Twelve "[[Recap/DoctorWhoS27E6Dalek You would make a good Time Lord]]" — which the Doctor sees as a much more hurtful comment than "You are a good Dalek."
127* TheCameo: Ben, Polly, and the Mondasian Cybermen appear in the opening PreviouslyOn sequence, but are absent from the rest of the episode — Mondas having been destroyed at the end of "[[Recap/DoctorWhoS4E2TheTenthPlanet The Tenth Planet]]", and time freezing before Ben and Polly catch up to One.
128* CastingGag: One is disappointed that he doesn't regenerate into someone physically younger when he thinks Twelve is next up, prompting Twelve to scream that he ''is'' younger. Creator/PeterCapaldi is older than Creator/WilliamHartnell was at the chronological time of his final story but younger than Creator/DavidBradley, meaning they are both right from a certain point of view.
129* ChristmasEpisode: The fourteenth and last in the franchise until 2023. It's also the third to double as a GrandFinale for an outgoing Doctor.
130* ChristmasMiracle: How the story ends on an EverybodyLives note (discounting the Doctors having to regenerate): The Twelfth Doctor is able to move the Captain's standoff a few hours ahead so it can be interrupted by a ''real life'' example of this trope, the Christmas Truce, which he explicitly describes to the First Doctor as "a human miracle".
131* ChronicHeroSyndrome: The Twelfth Doctor finally decides to regenerate because, as the Testimony avatars and later the TARDIS remind him, the universe still needs his aid — the Doctor even notes to the TARDIS that they'll probably screw things up without him — and at hearts he cannot bear to turn his back on those in need.
132* {{Cliffhanger}}: The episode ends with Thirteen flung out of the TARDIS as it's exploding, necessitating a new console room; wherever she lands will presumably be where she finds her new companions. Since where and/or when the TARDIS dematerializes to is unknown, the Doctor may or may not be stuck on Earth in ThePresentDay for a bit.
133* ComicallyMissingThePoint: When the Doctors and the Captain first enter Twelve's TARDIS, One thinks that it's his TARDIS, and he's been burgled upon seeing the revamped interior.
134* ContinuityNod:
135** The First Doctor [[Recap/DoctorWhoS10E1TheThreeDoctors doesn't react well]] [[Recap/DoctorWho50thASTheDayOfTheDoctor to the much-changed decor]] [[Recap/DoctorWhoS34E1DeepBreath of his future self's console room]].
136** Villengard, home of the weapons factories that the Doctor destroyed at some point in his lives according to the Ninth Doctor storyline "[[Recap/DoctorWhoS27E9TheEmptyChild The Empty Child]]"/"[[Recap/DoctorWhoS27E10TheDoctorDances The Doctor Dances]]", features in this episode. That two-parter was Moffat's first official ''Doctor Who'' script.
137** One is perplexed by Twelve using the Sonic Screwdriver, seemingly not knowing what a "sonic screwdriver" even is. This makes sense, as [[EarlyInstallmentWeirdness One never used a sonic during his run]], the first use [[Recap/DoctorWhoS5E6FuryFromTheDeep being done by Two in 1968]]. One relied on his trusty signet ring instead.
138** The Doctors and Bill end up in One's TARDIS — and in addition to the traditional roundels, one wall of it has [[http://www.radiotimes.com/news/tv/2017-12-06/do-these-new-doctor-who-christmas-pictures-reveal-a-secret-callback-to-the-50th-anniversary-special/ the same hexagon design on its walls]] as the Curator's gallery in "[[Recap/DoctorWho50thASTheDayOfTheDoctor The Day of the Doctor]]" did.
139** When the Twelfth Doctor realizes the Captain is confused and distressed by Twelve calling his war World War '''One''', he tells him he can't explain matters further by using River Song's favorite warning — "Spoilers."
140** To "[[Recap/DoctorWho50thASTheDayOfTheDoctor The Day of the Doctor]]".
141--->'''Twelfth Doctor:''' We do have one little advantage.\
142'''First Doctor:''' What advantage?\
143'''Twelfth Doctor:''' There's two of us.
144** When One and Twelve first enter Twelve's TARDIS and One is insisting he has no idea who Twelve is, Twelve tells him "I'd tell you to stop being [[ObfuscatingStupidity an idiot]], [[Recap/DoctorWhoS4E3ThePowerOfTheDaleks but I kinda know]] [[Characters/DoctorWhoSecondDoctor what's coming.]]"
145** Twelve makes a comment to One about remembering where to park and that it's "going to come up a lot". The number of times the Doctor has ''forgotten'' where he parked, parked in a place that eventually becomes inaccessible, or parked in a place that results in him being separated from the TARDIS is astonishing. The Twelfth Doctor just ended up in this position in "[[Recap/DoctorWhoS36E11WorldEnoughAndTime World Enough and Time]]"/"[[Recap/DoctorWhoS36E12TheDoctorFalls The Doctor Falls]]" (the TARDIS couldn't travel from one end of the ship to the other, and he and his friends couldn't take the lifts back to it in the second half — had it not been for Heather, he'd never have been returned to it) and listing ''all'' the other times (that we know of) would take forever.
146** While he's dying, Twelve once again asks [[Recap/DoctorWhoS35E11HeavenSent why he can't just rest]].
147** As indicated during his pre-regeneration monologue, the Doctor [[Recap/DoctorWhoS29E8HumanNature still hates pears]].
148** When Twelve regenerates, one of the first post-regeneration shots is of a ring slowly falling down the Doctor's (now) more slender fingers. [[Recap/DoctorWhoS4E3ThePowerOfTheDaleks When the First Doctor regenerated]], Ben and Polly tried to confirm his identity by making him wear One's ring, which wouldn't fit Two's more slender fingers. Fittingly as both Doctors just had this adventure together.
149** The Testimony originate from New Earth, first introduced in [[Recap/DoctorWhoS28E1NewEarth the episode of that name]] back in 2006.
150** Once again, [[Recap/DoctorWhoS35E8TheZygonInversion Twelve would rather nobody look into the browser history on his sonic sunglasses]].
151* CrucifiedHeroShot: Twelve strikes this pose when he '''finally''' regenerates. It is appropriate for many reasons: he is kinda-sorta dying and reviving, he is doing it to continue saving people, and he does it despite acknowledging that more pain and sorrow is likely in store for him.
152* CrypticBackgroundReference: When the Glass Woman shows the first Doctor his future and lists off his nicknames, some of them have never been heard on the show before. Most of those are connected to things that have been depicted on the show ([[Recap/DoctorWhoS31E12ThePandoricaOpens the Imp of the Pandorica]], [[Recap/DoctorWhoS23E4TheUltimateFoe the Shadow of the Valeyard]], [[Recap/DoctorWhoS33E13TheNameOfTheDoctor the Beast of Trenzalore]], [[Recap/DoctorWhoS35E12HellBent the Butcher of Skull Moon]]), but "The Last Tree of Garsennon" is completely new.
153* DeathSeeker: The Twelfth Doctor, since he no longer has anything WorthLivingFor and does not want to keep living in different bodies with different personalities. At the very end, he decides helping others is WorthLivingFor in and of itself.
154* DeliberateValuesDissonance: The First Doctor is sexist compared to the Twelfth — upon Bill and Twelve's reunion One suggests that she tidy up his later self's TARDIS. This reflects how much time, experience, and CharacterDevelopment have passed between the two incarnations in-universe, and out-of-universe the roles and depictions of female characters, especially companions, in ''Doctor Who'' since the show launched in TheSixties. It also prefigures the Doctor regenerating into a woman for the first time at the end of this story.
155* DespairEventHorizon: The Twelfth Doctor has once again reached this point (the first time was when he temporarily became a WoobieDestroyerOfWorlds in "[[Recap/DoctorWhoS35E12HellBent Hell Bent]]"), wanting to die for good if he cannot stay as he currently is, and the TARDIS has brought him to meet his previous self to bring him back from it and keep on living, along with convincing his first self to regenerate in the first place.
156* DetonationMoon: The collateral damage from whatever destroyed the Weapon Forges of Villengard includes the moon overhead.
157* DidIMentionItsChristmas: As with all of the Twelfth Doctor's Christmas adventures after his first one, "[[Recap/DoctorWho2014CSLastChristmas Last Christmas]]", Christmas itself has only a minor part to play in the story. The Doctor takes the Captain back to the start of the Christmas Truce, which ensures that he survives a standoff which would have been lethal.
158* DoNotGoGentle: Neither Doctor wants to regenerate and suffer the LossOfIdentity (a sort of death) that comes with it, and thus are fighting the impending change even if it means they have to die permanently. They wind up having one last adventure that ends in each accepting their transformation at last.
159* DoubleConsciousness: It's clearer in the novelization, but Glass People have these when they are serving as avatars of the dead. Glass!Bill is confused as to why she cannot remember things past Heather's arrival and is desperate to convince the Tweflth Doctor she ''is'' Bill Potts, but at the same time she remains an extension of the Testimony (which has temporarily given her LaserGuidedAmnesia) and it is observing the Doctors and Captain carefully to see if the former can be trusted. Her RevealingHug with the First Doctor has her switching from Bill's personality to speaking as the Testimony.
160* DrivingQuestion:
161** Why has the TARDIS brought the Twelfth Doctor to meet his original self?
162** What exactly are the "enchanted glass people" who can travel through and ''freeze'' time, what do they do to the innocents they kidnap, and why are they doing it?
163* DyingAlone: Or rather regenerating alone; Twelve is alone in the TARDIS when he regenerates.
164* EmbarrassingBrowserHistory: The Twelfth Doctor enjoys the sight of his Edwardian-looking past self wearing the sonic sunglasses...until his predecessor notices something called 'browser history'.
165* TheEndOfTheBeginning: Twice over. Promotional copy for this episode even included "It's the end of an era. But the Doctor's journey is only just beginning."
166** The First Doctor is just ''The'' Doctor from his perspective at the beginning of the episode, and he does not want to regenerate. His choice to do so in the end, which involves accepting that he will be taking a more active role in protecting others and especially humanity, allows the entire rest of ''Doctor Who'' to unfold.
167** Between "[[Recap/DoctorWhoS36E11WorldEnoughAndTime World Enough and Time]]", "[[Recap/DoctorWhoS36E12TheDoctorFalls The Doctor Falls]]", and this episode, the Twelfth Doctor has his FinalBattle and HeroicSacrifice, has his MythArc with Missy wrapped up, and sees a few of the major loose ends of his tenure resolved as he bids his final farewells to those he loves (or at least their avatars). While he also goes into this episode wanting to just reach The End, he decides to regenerate after all — becoming a ''she'' in the process, which in a meta sense opens many new possibilities for the franchise.
168* EndOfAnEra: This episode marked the end of Creator/StevenMoffat's tenure as showrunner, as well as the last story to be scored by Music/MurrayGold.
169* EnemyMine: The Doctor tells Rusty that he should help him because that will piss off the Daleks.
170* EverybodyLives: Comes with NoAntagonist, and even the Captain is eventually saved from his fate by the Doctor.
171* EvilPlan: Only it's not. The Twelfth Doctor is rather flummoxed.
172-->"Oh, it's not an evil plan. I don't really know what to do when it isn't an evil plan."
173* ExplainExplainOhCrap: When Bill first appears, Twelve asks how she can be here if she was a Cyberman last he saw her. Bill explains how Heather showed up and brought her back. Then the Doctor asks where Heather is. Bill doesn't have a good answer for that one, leading to the Doctor figuring out that she's a construct of the Testimony. The novelization explains that Glass!Bill's memories have been edited so she'll interact with the Doctor exactly as they did before they parted, though poor Glass!Bill initially doesn't realize this.
174* ExtremelyShortTimespan: Events unfold over a few hours at most; given that the two Doctors are at regeneration's door, a longer adventure just isn't in the cards.
175** Taking "[[Recap/DoctorWhoS4E2TheTenthPlanet The Tenth Planet]]" into account, One's side of this story unfolds over a day or so in total, also falling under this trope. By comparison, Twelve's side — from first talking to Bill and Nardole about his plans for Missy in "[[Recap/DoctorWhoS36E11WorldEnoughAndTime World Enough and Time]]" to his finally regenerating — unfolds over a month or so.
176* FaceDeathWithDignity: A major theme of this story.
177** The Captain is prepared to do this on the battlefield, and only becomes more determined to do so when he learns that's exactly how history records it. This is even in the face of the hope that he might escape his fate due to the Doctors. In the end, he doesn't have to die after all thanks to the Twelfth Doctor's timeframe shifting, but by that time the Testimony has given him LaserGuidedAmnesia of the events he undergoes out of time (he does stop short upon seeing Twelve among the people at the Christmas Truce, but that's all) and all he truly knows is that he was ready to die when a human miracle spared him.
178** The First Doctor is unwilling to regenerate and suffer the metaphorical death (LossOfIdentity) that comes with it because he's afraid of his future as other selves, but after the Twelfth Doctor's example shows him the good he'll be able to do, he accepts and peacefully gets on with it.
179** The Twelfth Doctor is unwilling to regenerate because he's just '''tired''' of living and changing altogether due to WhoWantsToLiveForever, especially in the wake of "[[Recap/DoctorWhoS36E11WorldEnoughAndTime World Enough and Time]]"/"[[Recap/DoctorWhoS36E12TheDoctorFalls The Doctor Falls]]"'s events (and by extension, "[[Recap/DoctorWhoS35E12HellBent Hell Bent]]"'s) reminding him he has ''no one'' who might be at his side forever. He invoked this trope when he defeated the Cybermen in "The Doctor Falls", in fact, and only Bill's Puddle-enhanced tears saved him from his permanent death. Although he is ready to embrace the end of everything at last for most of this story, he finally decides that he can't turn his back on a universe that he knows needs him, a motivation born of both ego and kindness. He still fits this trope in that he accepts the metaphorical death of regeneration to do so, just as One does.
180** The {{Novelization}}'s explanation of Bill's post-"The Doctor Falls" life reveals that she and Heather ultimately decided to live and grow old together as humans after time spent exploring the universe and getting to know each other better. When Bill's once-more-mortal body wore out, she decided not to be turned back into a Pilot like Heather and thus rejuvenated and immortal, but rather allowed herself to die for good. However, she told Heather she should feel free to be a Pilot again, and Heather obliged. As Bill saw it, both of them were free of their old bodies, just in different ways. But at the same time she will not allow the Twelfth Doctor the same "luxury of mortality" for himself because she knows how much the universe needs him.
181* FaceHugger: In a rare sight, A Dalek outside its casing attempts to exterminate the Captain, but it's soniced off by the Doctor.
182* FailedASpotCheck:
183** The First Doctor fails to notice the snow has frozen in place until Twelve points it out.
184** Twelve is so focused on the Glass Woman being an artificial construct of the ship that he misses the fact that her face is asymmetrical, which would not be the case were the computer merely imitating a human. As One notes, she must be modeled after an actual human.
185* FinalSpeech: The Twelfth Doctor gets one before he regenerates at last, addressed to his next self. Given that this Doctor was particularly good at speeches, this is fitting.
186-->'''The Doctor:''' Oh, there it is. Silly old universe. The more I save it, the more it needs saving. It's a treadmill. ''[the TARDIS makes argumentative noises]'' Yes, yes, I ''know'' they'll get it all wrong without me! ''[the TARDIS beeps in approval]'' Well, I suppose one more lifetime won't kill anyone... Well, except me... You wait a moment, Doctor! Let's get it right. I've got a few things to say to you. Basic stuff first. Never be cruel, never be cowardly. And never ever, ''ever'' eat pears! Remember, hate is always foolish and love is always wise. Always try to be nice, but never fail to be kind. Oh, and you mustn't tell anyone your name — no-one would understand it anyway. Except... ''[collapses to the floor and winches in pain]'' Except, ''children.'' Children can hear it, sometimes if their hearts are in the right place, and the stars are, too. Children can hear your name... ''[groans as he struggles to get back on his feet]'' But nobody else, nobody else, ''ever. [manages to stand up again]'' Laugh hard, run fast, be kind... ''[takes a moment to straighten his clothes a bit]'' Doctor, I let you go.
187* {{Flanderization}}: The First Doctor, unlike in his original run of stories, is portrayed as straight-up sexist with regards to the role of female companions — an attitude PlayedForLaughs as the episode's RunningGag. This is an atypical example of the trope — it's downplayed as it involves a single appearance of a character who hasn't been seen for decades in anything more than stock footage and his character isn't ''completely'' defined by sexism. It's also justified as Moffat and company are poking fun at mores of TheSixties as compared to those of TheNewTens, and how societal changes have been reflected in the show, partially by way of setting up the GenderBender regeneration of the Twelfth Doctor into the Thirteenth at the end of the story.
188* FlashbackWithTheOtherDarrin: The events of "[[Recap/DoctorWhoS4E2TheTenthPlanet The Tenth Planet]]" are seen in the PreviouslyOn sequence, this time with new actors playing the Doctor, Polly, and Ben.
189* FutureMeScaresMe: The First Doctor is upset to learn what he'll become and go through many regenerations down the line, starting when Twelve proves his identity to him via the glow of regeneration energy — for one thing, One thought he'd regenerate into someone ''younger-looking'' than Twelve. Much more seriously, finding out he'll be known as such things as "The Doctor of War" terrifies him, but The Testimony and later Twelve show him that he need not be afraid.
190* GenderBender: The Twelfth Doctor regenerates into a woman at the end.
191* GladIThoughtOfIt: One points out that the Glass Woman has an asymmetrical face and thus must be based on a real person. Later, in One's TARDIS, Twelve brings up her face on a monitor and explains how he noticed that. One protests, so Twelve jokes how they're the same person.
192* GoodAllAlong:
193** The Doctor initially presumes the Testimony is some kind of nefarious plot, because that's the modus operandi of the show. Eventually he learns it's a future initiative meant to preserve the memories of the dead so they can be better remembered, and has only good intentions. Twelve is genuinely flummoxed.
194** In the {{Novelization}} it's explained that the Testimony initially doesn't know if the Doctor is good and means well in trying to save the Captain, given his reputation as the Doctor of War and so forth. This is why it allows the glass avatar of Bill Potts to follow them out of the ship, and her interactions with One and Twelve help convince it that the Doctor is good all along.
195* GoodCounterpart: The Testimony is this to the Nethersphere of Series 8 — where that storehouse of departed humans' consciousness was all a scheme to create a Cybermen army, the Testimony's collected memories allow the dead to be lovingly, respectfully remembered and even to live again ''as they were'' after a fashion. It's even referred to as "Heaven on New Earth".
196* GoodIsImpotent: The First Doctor thinks this, because the traits associated with 'good' seem to contradict those necessary for survival or success.
197* GoodIsNotNice: Played with. As he's about to regenerate, the Doctor gives his future self some advice in the form of rules to live by. "Try to be nice" is the only one which is worded as optional, "but always be kind."
198* GrandFinale:
199** This is the third and final part of the Twelfth Doctor's, the first two parts being "[[Recap/DoctorWhoS36E11WorldEnoughAndTime World Enough and Time]]" and "[[Recap/DoctorWhoS36E12TheDoctorFalls The Doctor Falls]]". It's also been confirmed as companion Bill Potts' final appearance (for now).
200** This is also a retroactive one for the First Doctor, seeing as for him it takes place after his first confrontation with the Cybermen but before he regenerates.
201** In a meta sense, much like "[[Recap/DoctorWhoS30E17E18TheEndOfTime The End of Time]]" for Creator/RussellTDavies, this episode serves as the finale of Steven Moffat's tenure on the show.
202* HandWave: The First Doctor's somewhat different appearance is suggested by Twelve to be an effect of his regeneration being unstable, so his face is "all over the place".
203* HeroicSacrifice: Both Doctors really, really don't want to accept regeneration. One is afraid of his future, and Twelve is simply tired after all he's been through in this incarnation alone, never mind the LossOfIdentity issues. But each decides that it's better that they give up their current lives so that their successor(s) may exist and help others.
204* HistoricalPersonPunchline: Done with a person of in-universe significance; it's not until they're saying goodbye that the Doctor asks the Captain's name and learns that he's an ancestor of Brigadier Lethbridge-Stewart.
205* HistoryRepeats:
206** Once again, Steven Moffat [[Recap/DoctorWhoTheCurseOfFatalDeath bears witness to a Thirteenth Doctor who is female]]. Also fittingly serves as {{Bookends}}, as that was the first televised story he wrote for ''Doctor Who'' (though absolutely non-canon), and this one is his last (at least as showrunner).
207** Moffat's run began and ends on the same note: the Doctor regenerating and subsequently blowing up the interior of the TARDIS.
208** At the end of an emotional confrontation with one of his great enemies and after an ensuing HeroicSacrifice, a bitter, cynical, middle-aged Doctor regenerates into a new, young incarnation with bright brown eyes and a charming smile. This change — marking the passing of the torch from a well-known veteran actor to a total dark horse — leaves fans uncertain, but mostly hopeful. [[Recap/DoctorWhoS27E13ThePartingOfTheWays Here we go again.]]
209** As in the first Twelfth Doctor ChristmasEpisode, "[[Recap/DoctorWho2014CSLastChristmas Last Christmas]]", he is reunited with his most recent companion not long after — at least from the Doctor's perspective — they seemed to have parted ways forever with neither knowing the truth about the other's situation.
210** [[Recap/DoctorWhoS30E17E18TheEndOfTime Once]] [[Recap/DoctorWho2013CSTheTimeOfTheDoctor again]], the Doctor's regeneration story has the word "time" in its title.
211** Not to mention it has the Doctor angsting about regeneration on the last episode of a showrunner's tenure, even after his last incarnation was perfectly fine with regenerating and everyone knows it's going to happen.
212** Steven Moffat [[Recap/DoctorWho50thASTheDayOfTheDoctor retroactively shakes up the established order of the regenerations yet again]], this time targeting the circumstances behind a regeneration rather than pulling a cut-and-paste addition to the existing incarnations (though we still end up with a new one by the end). Moreover, the Doctors involved in the multi-Doctor adventure are both due to meet the end of their lives, mirroring how War, Ten, and Eleven were about to fare.
213** A Moffat script once again has people being pulled out of time at a moment where TimeStandsStill for them, specifically in the final moments of their lives — just as happened with Clara in "[[Recap/DoctorWhoS35E12HellBent Hell Bent]]". In that story, it was the work of the Time Lords and the desperate Doctor; here, it's the work of the Testimony.
214** [[Recap/DoctorWhoS30E17E18TheEndOfTime Once]] [[Recap/DoctorWho2013CSTheTimeOfTheDoctor again]], the Doctor sees the first person to ever see that incarnation of him just before regeneration. This time, however, Clara ''isn't'' the last person Twelve sees; that would be Bill and Nardole going by the televised episode. In the {{Novelization}}, much the way Eleven had a vision of Amy Pond before he regenerated, Twelve has a vision of ''Thirteen''.
215* HopeBringer: The Doctor being this is discussed. Bill asks the First Doctor why he stole the TARDIS, only to clarify that she wants to know what he stole it ''for'', as opposed to what he was running ''from''. The Doctor gives a speech about how evil has an inherent advantage yet never seems to succeed, and Bill points out that he can't see that the cause is himself.
216** In the {{Novelization}} Thirteen is this to Twelve. She is the very last person he sees, in his mind's eye, before he lets the Doctor go, and the sight fills him with hope.
217* HopeIsScary:
218** A ContinuityNod to the Twelfth Doctor and Missy's closing conversation in "[[Recap/DoctorWhoS36E10TheEatersOfLight The Eaters of Light]]" has the Captain noting to Bill "That's the trouble with hope... it makes one awfully frightened."
219** The {{Novelization}} reveals that the Twelfth Doctor feels this way and wants to die, in part, so he doesn't have to deal with hope anymore. Given how badly things worked out regarding his hope that Missy was redeemable (though it was still better than he believes it to be), this is understandable. But hope ends up being the last thing he feels as he lets this life go so that Thirteen can exist.
220* HopeSpot:
221** Twelve destructively regenerates into Thirteen just as Ten did into Eleven. For a moment, it seems as if the TARDIS has weathered the energy release better than it did the last time. Then Thirteen presses a button and everything goes to hell.
222** Being snatched out of WWI by the Two Doctors gives the Captain one, and then he finds out he has to go back and die to save the time stream. He discusses how [[ConditionedToAcceptHorror spending so much time in the war]] made him NotAfraidToDie, but now that he had been given hope, he wasn't ready to give up his life.
223* IDontLikeTheSoundOfThatPlace: The Chamber of Death, where the humans kidnapped by the Testimony are kept (unconscious) to have their memories uploaded. No wonder the Doctors don't believe the Testimony could be benevolent. In truth, the name just refers to the inevitable fates of everyone there.
224* IHatePastMe: Twelve isn't thrilled by his original sexist self, to put it mildly. At one point, he tells One to stop talking. However, given One doesn't do this when Twelve isn't around (and as confirmed by the novelization), he's mostly doing it to wind him up, and it seems to be a case of the Doctor trolling and teasing himself ''again''.
225* IHaveManyNames: The Testimony refers to the many sobriquets of the Doctor, such as the [[DoctorWhoS31E12ThePandoricaOpens Imp of the Pandorica]], the [[Recap/DoctorWhoS23E4TheUltimateFoe Shadow of the Valeyard]], Recap/DoctorWho2013CSTheTimeOfTheDoctor the Beast of Trenzalore]], the [[Recap/DoctorWhoS35E12HellBent Butcher of Skull Moon]], the [[NoodleIncident Last Tree of Garsennon]], the [[Recap/DoctorWhoS25E1RemembranceOfTheDaleks Destroyer of Skaro]], and the [[Characters/DoctorWhoWarDoctor Doctor of War]].
226* ImColdSoCold: While facing death in a muddy shell-crater the Captain says, "Cold, isn't it? It's about to get colder, I suppose, for one of us."
227* ImpairmentShot: After the regeneration, the Doctor looks in a reflective surface to check out the new face, and it's shown from the Doctor's point of view, with a bit of blur and shake to show that the Doctor is still recovering.
228* INeedAFreakingDrink: The First Doctor notes that the brandy bottle isn't as full as it used to be in Twelfth's TARDIS. After seeing his future in the Chamber of the Dead, he realizes the reason for this.
229* InternalHomage: After Twelve regenerates, his ring falls from Thirteen's finger — as the First Doctor's ring no longer fitted the Second, after his regeneration.
230* InternalReveal: The Twelfth Doctor and Bill Potts each learn that the other was NOT KilledOffForReal in the previous episode; moreover Twelve learns that Bill is no longer a Cyberman. He's not entirely convinced. Turns out that ''this'' Bill is technically an avatar of the Testimony created from the memories of the original Bill, but for all intents and purposes she's the real deal.
231* IronicEcho: Bill Potts frets that she's [[Recap/DoctorWhoS34E1DeepBreath standing right in front of the Doctor, and yet he can't seem to see her]].
232* ItRunsInTheFamily: It appears TheBrigadier's ancestors were just as likely to keep a StiffUpperLip and remember their duty no matter what fantastical events occur to them. They were also just as willing to die for their country if they had to, as well.
233* TheKindnapper: The Testimony only kidnaps humans so that their memories may be downloaded and preserved, temporarily putting them to sleep so that they do not realize what has happened to them, and returning them immediately to the moment they were taken from. The only reason the Captain's situation is an exception is because the two Doctors meeting and threatening a major paradox (via One not wanting to regenerate) causes a disruption in the timeline and caused the Testimony to not able to pinpoint the exact time to return the Captain to.
234* LaserGuidedAmnesia: The trope comes up twice in the denouement.
235** When the Testimony unfreezes time upon the Captain being returned to the place of his death (or so it seems), it also wipes his memory of his kidnapping and subsequent adventure with the Doctors. He does, however, seem to vaguely recognize the Twelfth Doctor during the Christmas Truce.
236** Shortly after that, the Testimony restores the Twelfth Doctor's lost memories of Clara Oswald. They were lost because he underwent this trope in "[[Recap/DoctorWhoS35E12HellBent Hell Bent]]", originally intending Clara to lose her memories of him before Clara sabotaged the neural block and brought him to his senses — whereupon they activated it together and he got the short end of the straw since ''one'' of them had to so they wouldn't be able to keep traveling and stay together due to the Hybrid prophecy that their love fortold.
237** The {{Novelization}} clarifies that the glass avatar of Bill Potts is initially affected by this, unable to remember her many happy years with Heather because it would affect her interactions with the Doctors. After the Testimony decides the Doctor is GoodAllAlong, Bill's avatar can remember everything.
238* LateArrivalSpoiler: Several big ones for the Series 10 finale; the first trailer alone revealed that:
239** The Twelfth Doctor ''doesn't'' regenerate, after the cold open of "[[Recap/DoctorWhoS36E11WorldEnoughAndTime World Enough and Time]]" suggests that it's the HowWeGotHere conclusion of "[[Recap/DoctorWhoS36E12TheDoctorFalls The Doctor Falls]]" — rather, he puts it off a little longer.
240** The First Doctor meeting Twelve, the centerpiece of the story and ad campaign, is the {{Cliffhanger}} of "The Doctor Falls".
241** Played with regarding the fate of Bill Potts; in the {{Cliffhanger}} of "World Enough and Time" Bill Potts is fully Cyber-converted and thus seemingly doomed to a MercyKill or HeroicSacrifice, but Heather saves her and gives her a humanoid form once more in "The Doctor Falls". While the Bill seen in this episode turns out to be an avatar of the original, her form does reflect her happy fate, which she explains to the upset Doctor (who ''believes'' she died in a HeroicSacrifice). As well, that trailer confirmed that Pearl Mackie was appearing in this episode and ''not'' as Cyber!Bill, so...
242** And of course, last but not least, not only does the Twelfth Doctor choose to regenerate after all but in a huge twist he regenerates into a woman, because the BBC made no effort to hide it. It actually [[Administrivia/TropesAreTools prefers to publicize the new actor a little early to cash in on the buzz it generates.]]
243* {{Leitmotif}}:
244** "The Doctor's Theme", the Doctor's original revival-era leitmotif, can be heard during Thirteen's first moments.
245** The song "Breaking the Wall", which first appeared in "[[Recap/DoctorWhoS35E11HeavenSent Heaven Sent]]", and has been associated with Twelve all last season, returns when he's giving his FinalSpeech before regenerating.
246* LetUsNeverSpeakOfThisAgain: After hearing Bill call his future self an arse, One threatens her with a smacked bottom if he hears language like that again. An utterly mortified Twelve ''begs'' Bill to pretend that never happened. Bill won't agree to that, wanting it to be something they laugh about years from now.
247* LighterAndSofter: As a deliberate contrast to "[[Recap/DoctorWhoS36E11WorldEnoughAndTime World Enough and Time]]"/"[[Recap/DoctorWhoS36E12TheDoctorFalls The Doctor Falls]]", which put the Doctor and his companions (especially Bill) through the wringer, saw Missy's HeelFaceTurn [[HeelFaceDoorSlam stopped in its tracks]] by her previous self, and climaxed with the Doctor's HeroicSacrifice followed by his desperation to '''just die''', this story is a much more hopeful, uplifting, funny end to the Twelfth Doctor's saga. Even the title and the crisis are more whimsical than those of previous [=NewWho=] Doctor finales. It's also the first [=NewWho=] regeneration story in which the Last Great Time War is '''not''' a major plot point (that One will eventually be "The Doctor of War" is brought up and becomes a representation of his fears for his future, but that's all, and even ''that'' moniker gets a more hopeful interpretation put on it), and one of the rare ''Doctor Who'' episodes to have NoAntagonist. This follows in the footsteps of Twelve's previous Christmas episodes. "[[Recap/DoctorWho2014CSLastChristmas Last Christmas]]" and "[[Recap/DoctorWho2015CSTheHusbandsOfRiverSong The Husbands of River Song]]" were ultimately joyous codas to the extremely {{Bittersweet Ending}}s of Series 8 and 9, and "[[Recap/DoctorWho2016CSTheReturnOfDoctorMysterio "The Return of Doctor Mysterio]]" also looked to the future with hope even in the face of sorrow.
248* ManChild:
249** When examining Twelve's TARDIS, shortly before Twelve and the Captain start talking, One gives a little hop while examining the console.
250** One calls the Sonic Screwdriver a "ridiculous buzzing toy" and has an even lower opinion of Twelve's Sonic Sunglasses. It's implied that Twelve is self-aware of this trope and that's why he doesn't want to admit that the guitar is his.
251** Twelve gives a little hop while rushing over to the TARDIS and exclaiming that "you still call it a ship!"
252* MeaningfulName: "Twice Upon a Time" — as in revisiting a previous adventure with a past Doctor ''and'' both Doctors experiencing its events firsthand. Also echoes the traditional opening of a fairy tale; in the episode, the First Doctor says that much as he wishes it could be life isn't like a fairy tale, and the Twelfth Doctor says that it can be sometimes, often with the Doctor's help.
253* MeetYourEarlyInstalmentWeirdness:
254** The Twelfth Doctor meets the First (though, considering the Doctor, no instalment of his is ever non-weird). Much is made of how, at this point in his life, he still calls the TARDIS "the Ship", hasn't officially declared himself to be Earth's protector, and doesn't telegraph/state his plans to antagonists so blatantly.
255** The same goes for the TARDIS. The First Doctor's is seen in its original smaller and blocky shape as opposed to the much larger, bluer, and modernized one it now is; a few cosmetic changes like the windows, the lantern shape and the typeface of the "POLICE PUBLIC CALL BOX" placard and telephone drawer are apparent. Both the First Doctor and Bill call out the other TARDIS's windows (from their respective perspectives) as being the wrong size.
256* MessiahCreep: The Doctor being affected by this trope over their many regenerations is examined. The First Doctor is shocked to realize that his later lives will come to commit themselves to defending Earth and other worlds -- becoming known by such names as "The Doctor of War" in the process -- rather than just stumbling into crises and finding their way out of them, partially because he believes GoodIsImpotent. Glass!Bill realizes that he doesn't believe the concept of a HopeBringer actually exists, much less that he can be that very thing. It's Twelve's rescue of the Captain from his seemingly inevitable death that makes One understand the full potential of his future lives.
257* MilesToGoBeforeISleep: One and Twelve are both regenerating despite their best efforts, but end up roped into one final adventure.
258* MissingTrailerScene: The Twelfth and First Doctors' exchange "We do have one little advantage", "What advantage?", "This time there's two of us" does not appear in the episode. The scene of the Captain walking up to them and asking if either is a Doctor is also shot from different angles in the trailer, and several other shots are also missing. It would appear that the Doctors' exchange is just part of the half-hour's worth of {{Deleted Scene}}s from this episode.
259* TheMole: Bill is a benign version, a Glass Avatar of the original Bill slipped onto the ship under the guise of her being the real one. Her purpose isn't to manipulate the Doctors but simply to observe them, and it's still Bill's mind so she would never harm the Doctor. (Twelve actually gathers and states evidence that she isn't the original Bill almost immediately, but this is quickly put on the back burner and he doesn't learn what her actual purpose is until later.)
260* {{Motifs}}: One last set for Series 10:
261** The value of individual lives: The Doctors are facing an entity that kidnaps specifically chosen humans out of time, one by one. Why do they do it, and why are they picking ''these'' people in particular? Is it really worth rewriting history to save just one soldier from the grave? And how can each Doctor — but especially the Twelfth — be convinced to go on living (enduring LossOfIdentity in the process) and helping others instead of embracing eternal rest after all their good works?
262** Exploitation: Low-key version: The Testimony is benevolent, but it ''is'' kidnapping people to access/duplicate their memories.
263** Hidden threats: Turns out that there was ''another'' crisis taking place alongside the Cybermen's first-ever encounter with the Doctor. Subverted with the issue of Glass!Bill turning out to be TheMole, as she is ''not'' a threat.
264** Imprisonment/release: Those picked out by the Testimony to be "uploaded" are temporarily imprisoned by it.
265** "Villains" that aren't actually evil: The Testimony and its Glass People are a human version of the Matrix ''and'' a benevolent version of the Nethersphere, collecting the memories of deceased humans for posterity and prosperity.
266* MythologyGag:
267** The First Doctor assumes that his regeneration will make him younger. Not only was Creator/PatrickTroughton younger than Hartnell, the original intention of the "renewal" (as it was called in 1966) was that the Second Doctor actually ''was'' a younger version of the First Doctor.
268** At the age of 59, Capaldi spent the entirety of the tenth season and this Christmas special being the oldest actor to headline the series, overtaking Hartnell in February 2017.[[note]]There have been older actors to have played the Doctor — most notably, [[Creator/JohnHurt Sir John Hurt]] at 73 and Creator/DavidBradley at 75 — but Capaldi is the oldest series lead.[[/note]]
269** The Captain's mention of Cromer is a reference to the Brigadier's mention of Cromer in "[[Recap/DoctorWhoS10E1TheThreeDoctors The Three Doctors]]" (and a hint to the kind of fan who remembers things like that that the two characters are connected).
270* NoAntagonist: The Glass People ''do'' plan something, but they aren't malevolent.
271-->'''Twelfth Doctor:''' It's not an EvilPlan. Well, I don't really know what to do when there isn't an EvilPlan.
272* NoodleIncident: We know the Doctor was at Skull Moon during the Time War, as revealed in ''Heaven Sent'', but just ''what the hell did he do there'' to be known as "The ''Butcher'' of Skull Moon"?
273* NotEvenBotheringWithTheAccent: The actor playing Ben doesn't even bother with a Cockney accent.
274* NothingIsTheSameAnymore: The two Doctors don't want to regenerate because the nature of regeneration invokes this trope. They won't have the same personality and have to, in a sense, start their lives afresh — especially Twelve, who has just lost his companions and Missy, leaving him with no one who could help ease the transition as his side of the story begins. Ultimately, not only do both of them accept this trope but the entire ''franchise'' won't be quite the same because Twelve's regeneration involves a GenderBender, resulting in the Doctor's first female incarnation. This also calls back to the First Doctor’s regeneration, which was also a major change to the franchise.
275* {{Novelization}}: By Creator/PaulCornell, which goes into much greater detail on the ultimate fates of Bill and Nardole among other things.
276* NoYou: Rusty's response when the Doctor calls him "a good Dalek."
277--> '''Rusty:''' I am not a good Dalek. ''You'' are a good Dalek.
278* TheNthDoctor:
279** [[TropeNamer Obviously]], since it's a regeneration episode; three Doctors appear in full, and we get glimpses of the others when the Glass People show One their archives, and when One regenerates.
280** In addition, the difference in appearance between Creator/WilliamHartnell and Creator/DavidBradley is explained by One's regeneration already having started.
281* ObligatoryJoke:
282-->'''The Captain:''' So sorry. I don't suppose either of you is a doctor?\
283''[One and Twelve give each other an AsideGlance]''\
284'''Twelfth Doctor:''' You trying to be funny?
285* ObliviousToHisOwnDescription: The First Doctor admits that one reason he left Gallifrey was to try and answer why good always prevailed over evil when, objectively, evil should typically win because BeingGoodSucks. Bill suggests that it could be because of a single bloke running around, helping where he can and maintaining good in the universe as a result. The Doctor dismisses this as a fairy tale.
286* OfCourseImNotAVirgin: The First Doctor and the Captain both feel it necessary to mention that they have "some experience of the fairer sex"; Bill promptly retorts that she does, too, much to their surprise.
287* OhCrap:
288** Twelve has this reaction when he realizes that he just confused an officer from the Great War by referring to it as "World War ''One''".
289** For that matter, the officer himself is visibly stunned that all the horror and bloodshed he's seen and endured is [[FromBadToWorse merely the first go-round of it]].
290** At the end, Thirteen's reaction to getting tossed out of the TARDIS and into freefall is the page image for ''Doctor Who''[='s=] [[OhCrap/DoctorWho subpage]].
291* OnceMoreWithClarity: We see how the ''Twelfth'' Doctor was involved in "[[Recap/DoctorWhoS4E2TheTenthPlanet The Tenth Planet]]", and we also get more information about the First Doctor's condition near his demise.
292* OntologicalMystery: How and why exactly is a World War One captain in the middle of the South Pole in 1986?
293* OutsideContextProblem: Several times over:
294** The First Doctor was trying to avoid regenerating after "[[Recap/DoctorWhoS4E2TheTenthPlanet The Tenth Planet]]" when he ran into a future self on the way back to his TARDIS.
295** The Twelfth Doctor was also trying not to regenerate when the TARDIS elected to bring him to the South Pole and meet himself to convince ''him'' to regenerate.
296** ''Then'' the two Doctors find themselves having to deal with the Testimony.
297** To the Testimony the Doctors' presence is an outside context problem, because they accidentally caused the Captain to be returned to the wrong place and time.
298** And the Captain is in the middle of a life-and-death standoff on a battlefield of World War I when he's taken away by the Testimony in the first place.
299* PlotParallel: Both the Captain and the German soldier don't want to kill the other, but since PoorCommunicationKills is in play neither realizes that. PoorCommunicationKills is also the problem the Doctors and the Testimony have: the Doctors don't realize the Testimony doesn't have an EvilPlan because it doesn't just explain itself, and the Testimony doesn't know the Doctor personally and doesn't know that his actions over the space-time continuum — those that have given him the "Doctor of War" reputation — are far more often than not motivated by good intentions, even if they often ended in tragedy and destruction.
300* PoliticallyIncorrectHero: Played with because it involves two incarnations of one character — the First Doctor is sexist compared to the Twelfth.
301* PoorCommunicationKills:
302** The whole episode could have been resolved in 10 minutes tops had the Glass People explained what they were doing right up front and why.
303** Also literally the case between the Captain and the German soldier (before the Doctor fixes the situation). Each of them urges the other to simply go, not wanting to kill them, but doesn't understand what the other is saying due to not speaking the same language.
304* PreviouslyOn:
305** Exaggerated, with perhaps the biggest gap in history between the "previously on" and the episode it's referencing.
306--->Previously, on ''Doctor Who''\
307[[LongRunner 709 episodes ago]]
308** It also has a twist in that rather than recapping "[[Recap/DoctorWhoS36E12TheDoctorFalls The Doctor Falls]]", it shows what the First Doctor, Ben and Polly are up to in "[[Recap/DoctorWhoS4E2TheTenthPlanet The Tenth Planet]]", the previous adventure from ''their'' perspective. From there, One leaves his companions behind and ends up walking right into the {{Cliffhanger}} of "The Doctor Falls".
309* ThePromise: Bill asks the Twelfth Doctor to "Come back alive" from what turns out to be a consultation with Rusty. He tells her "Be here [at the TARDIS] when I do", thus making this. It becomes a moot point.
310* {{Retcon}}: When "[[Recap/DoctorWhoS4E2TheTenthPlanet The Tenth Planet]]" aired, the term "regeneration" hadn't been coined and the writers were quietly and vaguely trying to describe what happened to make the Doctor change appearance as though he just got younger and was still the same, looking for an excuse to write Hartnell out and pussyfoot away from the issue. Now that regeneration has solidified as a core concept in ''Doctor Who'', the issue is approached more directly with the First Doctor and Twelfth Doctor openly discussing that they don't want to "regenerate" as opposed to merely "change", and the last moments of the First Doctor are treated with more eloquence and grandeur by showing [[DoNotGoGentle he had one last thing to do before his time was up and refused to go quietly]]. There's also the fact that the First Doctor is shown with his hands glowing with the golden glow of regeneration energy, which is how regeneration has consistently been depicted in the revival; in the original series each regeneration was a case of DependingOnTheArtist, with One's simply being a fade to white achieved by exploiting a mechanical fault with one of the cameras.
311* RevealingHug: Bill Potts hugging the First Doctor, before revealing that she's a Glass Woman. Not only her expression but her glass hands are shown.
312* RiddleForTheAges: While Paul Cornell's novelization (see AllThereInTheManual above) reveals the {{Surprisingly Happy Ending}}s of Bill Potts, Nardole, ''and'' the solar farmers from the previous episode, several unanswered questions remain.
313** Do the ''original'' Bill Potts and Nardole ever learn that the Twelfth Doctor survived "[[Recap/DoctorWhoS36E12TheDoctorFalls The Doctor Falls]]"? The novelization suggests they don't, but it's not confirmed.
314** The very first glimpse audiences had of the Twelfth Doctor was of him helping his previous selves rescue Gallifrey in "[[Recap/DoctorWho50thASTheDayOfTheDoctor The Day of the Doctor]]". With this episode, the question of when that happened from his perspective may never be answered.
315** And now that Bill and the Doctor's relationship is apparently over for good: Where did the spaceship that left the [[Recap/DoctorWhoS36E1ThePilot puddle]] that possessed Heather and led to Bill becoming the Doctor's companion come from?
316* RunningGag:
317** The First Doctor's sexism, and the Twelfth Doctor and Bill being offended and embarrassed by it.
318** The Doctor telling his next incarnation to never eat pears was originally taken from the novel that the Tenth Doctor story "[[Recap/DoctorWhoS29E8HumanNature Human Nature]]"/"[[Recap/DoctorWhoS29E9TheFamilyOfBlood The Family of Blood]]" was based on. David Tennant improvised a reference to it during filming which was released online and included with the DeletedScenes on the DVD, but not in the episode itself. Peter Capaldi's last advice to Clara before losing his memories of her included an admonition to never eat pears, "That one's important, you should write it down!" Now, the Doctor feels warning his next self not to eat pears is on the same level of importance as being kind or never telling their name. For bonus points, Paul Cornell, who wrote ''Human Nature'' and its television adaptation, wrote this episode's novelization!
319** It also gets in on the series-long running joke where almost no incarnation of the Doctor can ''ever'' enter another's TARDIS control room without talking smack about it.
320--->'''One:''' My TARDIS! Look at my TARDIS!\
321'''The Captain:''' It's impossible...\
322'''One:''' Have I been burgled?\
323'''The Captain:''' [[CatchphraseInterruptus But it's-]]\
324'''One:''' Hideous!
325* SayingTooMuch: The Captain is naturally disturbed to hear the Twelfth Doctor refer to the Great War as World War ''One''. It's a good job the Doctor didn't say he'd taken part in [[Recap/DoctorWhoS14E6TheTalonsOfWengChiang World War Six]].
326* SeenItAll: When Bill discovers the Doctor has brought her to a devastated planet where someone really wants to kill him, she just sighs and follows him out.
327* SelfDeprecation: Twelve says he'd tell One to "stop being an idiot, but [he] knows what's coming" — reaffirming the way he described himself in "[[Recap/DoctorWhoS34E12DeathInHeaven Death in Heaven]]" — and downplays Doctors Two to Eleven as "a few false starts" when the First Doctor asks if Twelve is the man One will become.
328* SeriesContinuityError: The PreviouslyOn segment claims that the events of "[[Recap/DoctorWhoS4E2TheTenthPlanet The Tenth Planet]]" happened "709 episodes ago". Discounting the fact that this is only how far back the first episode of that story happened, this numbering excludes "[[Recap/DoctorWhoS17E6Shada Shada]]", which is odd considering that story was completed with animation the same year this episode was released. All things considered, "The Tenth Planet" could more accurately be said to have happened 712-715 episodes ago.
329* SiliconBasedLife: Glass People are humanoid but completely see-through when they aren't serving as avatars of the dearly departed, like living glass sculptures.
330* StableTimeLoop: The Twelfth Doctor can't exist and be brought back to the past to meet his original self unless the First Doctor regenerates, and at the time Twelve arrives One doesn't want to, so the story involves Twelve creating this — which ends up helping him accept the prospect of his own regeneration along the way. The possibility of the loop not being created ''and'' the disastrous paradox that would take place if both Doctors died at once causes the temporal disturbance that interrupts the Testimony returning the Captain to the battlefield in the first place.
331* StrawMisogynist: The First Doctor comes out with a string of StayInTheKitchen remarks. These appear to set up the Twelfth to tell him he's wrong, and to be the butt of IHatePastMe jokes.
332* SunglassesAtNight: One mocks Twelve for wearing sunglasses indoors, regardless of how functional they are. Twelve gets One to try them, but changes his mind when One sees something labeled "Browser History".
333* TakeMeInstead: The Captain, upon seeing how much Twelve cares about Bill Potts, offers his life to the Testimony in exchange for hers. This is before he and the Doctors understand exactly how it works and what its purpose is, and moreover that Bill is an avatar of it.
334* {{Technobabble}}: When the Glass Woman explains to the Captain that he won't remember what happened and a perception filter will hide their presence once time resumes, he says that he assumes the words they just spoke probably meant something.
335* TemptingFate:
336** Twelve asks Bill to respect him "as I have always respected you." Bill promptly calls him an arse, then his younger incarnation appears and threatens to give her a smacked bottom.
337** "[[ItsProbablyNothing Probably just rats.]] I'm used to rats." Cue the FaceHugger.
338* ThisIsReality: When the First Doctor tells Bill that he's trying to understand how good prevails in an unkind universe, she suggests that it might be because there's somebody who goes around fixing things when they go wrong. He says that it's a nice idea, but he doesn't believe it because real life isn't like fairy tales.
339* ThisIsSomethingHesGotToDoHimself: The Twelfth Doctor leaves Glass Bill behind at the TARDIS as he heads off to consult Rusty, leading to ThePromise above. He also regards his regeneration as this, leaving Glass Nardole and Glass Bill behind to return to the TARDIS alone at the end.
340* TimeCrash: There is a critical paradox at the heart of this episode. If the First Doctor doesn't regenerate, then none of his future incarnations will exist. If he does it in the same time and place as one of those future incarnations, that's even worse.
341* TimeStandsStill: The battleground freezes, both literally and... well... [[WinterWarfare literally]], at the appearance of the Doctors. This is the work of the Testimony, who travel through time and freeze moments to kidnap humans.
342* ToMakeALongStoryShort: How come Bill is NotQuiteDead after being turned into a Cyberman? "Well, long story short. I totally pulled."
343* TomatoInTheMirror: Averted. In the episode Glass!Bill seems to know from the start that she's not the original (and in fact, not even human). She isn't particularly bothered by the fact and otherwise acts completely normal. The novelization gives this more depth: she ''is'' confused as to why she can't clearly remember her entire life with Heather. This is because the Testimony gave her LaserGuidedAmnesia so she'd interact with the Doctor as she did before they were parted, to better serve as TheMole. Once the Testimony is sure he is trustworthy and benevolent, all of her memories are restored.
344* TookALevelInJerkass: While he was never entirely free of chauvinism, the First Doctor is made a lot more overtly sexist than he ever was in his original adventures and "[[Recap/DoctorWho20thASTheFiveDoctors The Five Doctors]]".
345* TooMuchInformation: Nardole's glass nipples.
346* TrashTheSet: Just as with what happened with his [[Recap/DoctorWhoS30E17E18TheEndOfTime tenth incarnation]], the Twelfth Doctor's been holding back his regeneration for so long that when he finally lets it happen, it wreaks utter havoc on his TARDIS. After the regeneration, everything seems to be quiet, but when Thirteen pushes a button on the console, the TARDIS starts exploding again.
347* WalkingSpoiler:
348** The Captain. Nothing was revealed in promotional materials about him but his rank and temporal placement (World War I) even as Mark Gatiss was billed ''before'' Pearl Mackie in the trailer, Capaldi said he has a key role in the Doctor's lives, '''and''' he's the specific prey of the Glass People. Turns out he's one of the Brigadier's paternal ancestors. (Incidentally, the novelization gets around the issue of his name in the scenes told from his viewpoint by just calling him "Archie".)
349** For that matter, the Glass People/The Testimony themselves: The spoiler is they aren't actually villains, meaning the Doctor doesn't have an evil plan to thwart for once.
350* WarIsHell: Lampshaded by the Captain as he's in a standoff with a German soldier that he really doesn't want to kill, but knows he will anyway to prevent himself from being killed.
351* TheWatson: Along with previously-established companion Bill (albeit as a glass avatar), the Captain is this. In early drafts Bill wasn't even included precisely because she'd already had her HappyEnding in the previous episode and the Captain filled the function of a character the Doctors could explain things to, but Moffat decided the story needed more "fun" and found an unusual way to bring her back (and lift unwarranted guilt from the Doctor regarding her fate, which he felt at least partially responsible for and was not able to remedy). He mentions at times that he is "lagging behind" on what's going on.
352* WhamEpisode: The First and Twelfth Doctors meet near/at the end of their respective incarnations, and the Twelfth Doctor regenerates into their first female incarnation. Otherwise, no major changes are made to the mythos.
353* WhamLine: Near the end of the episode, we finally learn the Captain's full name: Archibald Hamish Lethbridge-Stewart.
354* WhamShot: The first trailer has no less than ''three'' of these.
355** Polly sees the First Doctor's hands glow with regeneration energy, [[{{Retcon}} in the same way that regeneration has been shown in the revival]].
356** Bill returns! (As it turned out, sorta!)
357** Although it's really just another Testimony avatar, [[Recap/DoctorWho2013CSTheTimeOfTheDoctor similar to the last time the Doctor regenerated]] we do get one final appearance from Clara and this definitively removes the Doctor's memory block from "[[Recap/DoctorWhoS35E12HellBent Hell Bent]]", allowing him to regain his memories of her.
358** And in the actual episode, no sooner has Thirteen finished her regeneration than the TARDIS tips sideways with its doors open and she's flung out in midair high above the Earth.
359%%%** The reveal of Creator/MarkGatiss's role is presented this way.
360* WhatHappenedToTheMouse: Nardole and Bill Potts's lives post-Doctor, up to and including the nature of their deaths, remain mysteries in the episode, though the novelization reveals them each to get a SurprisinglyHappyEnding (see AllThereInTheManual above). In the meantime, the faculty and students at St. Luke's have to be wondering what happened to that particularly long-tenured professor who just disappeared one day. For that matter, what becomes of the now-empty Vault?
361* WhatMeasureIsANonHuman: Downplayed — the Twelfth Doctor quickly figures out that Bill isn't the ''real'' Bill, and thus holds her at arm's length emotionally, trying to poke holes in her behavior and speech. Because Glass!Bill ''is'' created from the original Bill's memories, she has the same personality, way of thinking, and emotions, and is deeply hurt by his standoffish attitude, pleading with him to regard her as no different than the real deal. Although he does come to understand why the avatars exist and that they are good, and comes to treat them with kindness and appreciate the comfort (and memories) they give him, he never ''quite'' manages to just treat them as he would their human (or cyborg in Nardole's case) counterparts. After all, the existence of the avatars confirms to him that the originals — dear friends of his — are dead and gone, and that knowledge does not bring him much comfort at a very trying time of his life. The {{Novelization}} also explains that the Doctor is still wracked with guilt over his failure to rescue Bill from being Cyber-converted back in "[[Recap/DoctorWhoS36E11WorldEnoughAndTime World Enough and Time]]", which is one reason why he's so upset with the Testimony sending out an "imposter" who has her original form.
362** The novelisation confirms that Nardole's being saved from death in the Testimony is an exception, and that its designers intended it to only save humans.
363* WhoWantsToLiveForever:
364** At first. The Twelfth Doctor is really feeling his age, likening his lifespan to a deserted battlefield with himself as the last man standing. But then again, by the end of the episode this is subverted, as the Doctor is convinced that there are things WorthLivingFor and regenerates.
365** The {{Novelization}} reveals that Bill Potts came to feel this way. As much as she loved living the life of an immortal Pilot with Heather, their subsequent life as humans on Earth was even happier, and she ultimately chose to die as a human when that body became old and infirm rather than return to immortality. For her part, [[LivingForeverIsAwesome Heather did not feel the same way]], and Bill's dying request was for her to return to the stars and live as she wanted to. While Bill's avatar does understand the Twelfth Doctor's concerns in the end, she does not think he can afford the "luxury of mortality" because there's still so much good he can do for others if he regenerates.
366* WinterWarfare: The Captain comes from a World War I front line that's covered in snow, at a moment frozen in time to boot thanks to the Testimony, who have to follow him to the snowy South Pole and freeze time ''there'' too.
367* WomenDrivers: Averted. Though the TARDIS ''does'' explode and throw Thirteen out into freefall as soon as she tries operating it, this isn't because she's a woman. This is because the Doctor has failed to learn from past mistakes and regenerated inside the TARDIS again despite the [[Recap/DoctorWho2005CSTheChristmasInvasion previous]] [[Recap/DoctorWhoS31E1TheEleventhHour three]] [[Recap/DoctorWhoS34E1DeepBreath times]] they did so causing problems. The {{Novelization}} suggests that the regeneration is not the reason the TARDIS goes haywire, because it's starting to malfunction ''before'' he regenerates. Twelve even notices this, but it's too late for him to do anything about it...
368* WorthLivingFor: The Twelfth Doctor has just been put through the wringer, is dying, and has no companions to comfort him. He believes his attempt to induce a full HeelFaceTurn in Missy failed and that Bill was KilledOffForReal after being Cyber-converted by Missy's previous self as that villain's cruel response to the Doctor's efforts. If he regenerates, he'll lose the personality and appearance he's grown to be happy with and have to adjust to a new one all over again, and owing to his perpetual ChronicHeroSyndrome he'll face more dangers, more successes but also failures, and more friendships with mere mortals that will inevitably end in loss; in this life alone he lost two women he loved with all his hearts (the {{Novelization}} makes this especially clear with regards to River Song). Couple that with once again being essentially exiled from his homeworld on top of all this -- just because he tried to defy the Web of Time and save someone he loved from the grave, which wouldn't have happened if his people hadn't been plotting against him -- and he's determined to die for good. In the end, however, he decides to keep going after he realizes that being able to help others is WorthLivingFor.
369* YouWouldntShootMe: The Twelfth Doctor convinces Rusty the Dalek not to kill him because he would rather see him die.
370----
371->''"[[Creator/PeterCapaldi Doctor...]] [[PassingTheTorch I let you go.]]"''
372----
373->''"[[Creator/JodieWhittaker Oh, brilliant!]]"''\
374'''''[[HereWeGoAgain BOOM!]]'''''

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