Plot Archaeology

A plot arc that was incomplete and forgotten, and then suddenly brought back out of the blue to continue the plot arc itself. This is distinct from the Continuity Cavalcade and Continuity Porn tropes in that it's not just a Shout-Out type situation — the plot arc is resumed, essentially where it left off.

In short, what distinguishes this from similar tropes is that it's not just a one-episode reappearance, either as a Shout-Out or a full-fledged Sequel Episode (which may be considered a Sub-Trope).

Compare The Bus Came Back, Happy Ending Override, Conclusion in Another Medium, and Sequel Episode. Contrast Aborted Arc, which this may be a later result of. See also Un-Canceled, Post-Script Season, and Continuation.

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Examples:

Anime & Manga

• Macross: One of the series's biggest unresolved plot threads was the fate of the Megaroad-01, which was carrying the protagonists of the original Super Dimension Fortress Macross when it went missing. This was finally addressed in 2021 with the release of Macross Delta: Absolute Live, which reveals that Lady M, Xaos's Mysterious Benefactor, is the Megaroad-01, and in the climactic battle is shown in one of the fold tears complete with the silhouettes of Minmay and Misa on its bridge.
• Moriarty the Patriot: Moran's Day in the Limelight arc, The Man with the Golden Army, resolves with Moran's backstory dealt with and himself able to move on fully devoted to William, and all seems well. Until The Adventure of the Empty Hearts brings up The Great Game from his and Moneypenny's adventures back in India from that arc, and the plot is explicitly mentioned as a part of the same nefarious plot.
• My Hero Academia: During the Forest Training arc, it's revealed there is a traitor within UA acting as a mole to aid All For One. The point proceeded to be ignored for several, real-time years and there was even misinformation that the creator just forgot. Finally, Chapter 336 shows the traitor is Aoyama, who was forced to work for AFO and quickly sides with the heroes upon discovery, feeling crushing guilt for all he's done.

Comic Books

• The DCU usually does this with certain events in its history, reviving old (and more than finished) issues and collections just for the event's sake. Some examples are seen in the Blackest Night event where all the historical tiles of DC had one more number (i.e. if a collection finished on issue 405, the BN Special is the 406) and even some crossovers with actual characters as seen in events like Zero Hour: Crisis in Time! and Convergence.
  • A major offender is Booster Gold. Being a time traveller, Booster has had various numbers which were continuations of past events stories and still being part of them as tie-ins. Some examples are in DC One Million and Zero Hour: Crisis in Time!, usually made even decades after these events finished and still count as part of their collections.
• Doctor Who (IDW): The 12-issue arc "Prisoners of Time" is a 50th Anniversary celebration about all the Doctors against Adam Mitchell, an old companion from the Ninth Doctor, who never was mentioned again in the series after those two episodes, returns as the Big Bad, secretly managed by The Master.
• Guardians of the Galaxy: In the first story, in Marvel Super-Heroes #18, Charlie-27 finds his family have been shipped off to a Badoon labor camp, where the conditions will kill them if he doesn't get there in time. The next time the Guardians appeared, in Marvel Two-in-One, there's been a Time Skip and the fate of Charlie's family goes unmentioned from there on out, until the final issue of Marvel Present confirms that Charlie was unable to rescue them.
• She-Hulk: In the second volume of Dan Slott's run, She-Hulk is shown a Bad Future created by an event called the Reckoning War for which she is apparently responsible. What this war is or how She-Hulk causes it were never explained in the book and it was ignored after the issue it came up in. In 2021, Marvel announced a crossover event titled Reckoning War, which will finally explore the eponymous war, 17 years after it was first mentioned.
• Spider-Man:
  • The true identity of the Hobgoblin. The villain first appeared in 1983; his true identity, fashion mogul Roderick Kingsley, had first shown up three years prior, but according to his creator Roger Stern, he didn't plan on Kingsley as the Hobgoblin until much later, and that initially he didn't have an idea for who the Hobgoblin was, and instead planted a number of Red Herrings before deciding shortly afterwards that Kingsley was the culprit and he planned to reveal it after a long buildup in imitation of the original Green Goblin reveal. The problem? Stern quit, or was made to resign halfway through the Myth Arc with his consent, later writers who disliked the identity of Kingsley, decided to spin wheels and continue the mystery indefinitely leading to several more Red Herring — Flash Thompson, and a thug named Lefty Donovan — before in a desire to wrap up and clear house, Ned Leeds was Killed Off for Real and then, in an Ass Pull, "revealed" as the "true" Hobgoblin all along because the writers (and readers) had gotten tired of the mystery and decided to introduce a second Hobgoblin, mercenary Jason Macendale (hitherto a minor villain known with the alias Jack O'Lantern), who quickly and unintentionally became a Big Bad Wannabe. It wasn't until 1997 that Stern was invited back and allowed to wrap up the story as he originally intended it — quite remarkably, the Kingsley idea was still internally consistent to the story and caused no real plot holes (if you pay attention, at least).
  • Gerry Conway's graphic novel Parallel Lives, which was about the Peter and Mary Jane Watson romance, plugged in holes and developments made by the likes of Marv Wolfman and Roger Stern and Tom Defalco. Marv Wolfman had Mary Jane cite her parent's divorce as reasons for rejecting Peter's proposal, Roger Stern conceptualized Mary Jane's family history and background and hinted at her knowing Peter's secret and Tom Defalco revealed that Mary Jane rejected Peter's proposal and left New York to got to Florida because she couldn't deal with him being Spider-Man. Conway, who originally wrote and developed Mary Jane's character after Gwen's death, took up the baton, which left it ambiguous as to when Mary Jane knew his identity, and reconciled different parts of her character (Lee-Romita's Mary Jane who was a party girl) with later developments (she had Hidden Depths and was putting on a mask), deciding that Mary Jane knew right from the start, that she glimpsed Peter as Spider-Man on the night Uncle Ben died, and then revisited moments in Peter and Mary Jane's relationship which showed her keeping a knowing distance from him at various times.
• One of the plot points left hanging from the end of The Transformers Megaseries were the fates of Scorponok and the Magnificence, a mysterious artifact that was able to answer any question asked of it. Nearly a decade later in the pages of Transformers: More than Meets the Eye, Scorponok would resurface with the Magnificence in his possession, with the former going on to be a pivotal antagonist and the latter being revealed to be the Oracular Head of Epistemus, one of the Guiding Hand.
• X-Men:
  • Mystique reveals her true form to Nightcrawler, who is shocked that they look very similar. She mentions his mother's name. 10 YEARS (or more) later, it's revealed that she is his mother. It hadn't been even mentioned in the comics in-between those two points.
  • The Third Summers Brother. In 1993, Mr. Sinister casually refers to Cyclops having "brothers", then claims he misspoke. This plot got dropped when Fabian Nicieza left the X-titles before he could reveal that Adam X the X-Treme was Cyclops' half-brother. Over the next ten years, the concept was never referred to. (Robert Weinberg thought it was Apocalypse, but also left the book before he could say so). In 2004 Chris Claremont suddenly brought it up again and revealed it was Gambit, but that was in an Alternate Continuity. Then, in 2006, Scott and Alex finally met their younger brother Gabriel Summers, a.k.a. Vulcan – unfortunately, Vulcan's backstory makes it impossible that Sinister could have known about him in order to make that casual offhand reference. Eventually, in 2021, Adam X was confirmed to also be Scott's half-brother. Notably, Sinister didn't mention a specific number of brothers – only that Cyclops has more than just the one brother he was aware of at the time.
  • Following Age of Apocalypse, the Mutant Massacre storyline was revisited, with Dark Beast and Gambit being Retconned as having participated in the event.^note Dark Beast, who's studied under his world's Sinister, experimented on the Morlocks. The mainstream Sinister found out and got pissed at his work being "misappropriated", and duped Gambit, to Remy's eternal shame, into recruiting the Marauders.
  • In Onslaught, the X-Men use technology to remotely view the moment when Onslaught was created, when Professor Xavier attacked Magneto back during Fatal Attractions. Onslaught is also revealed as the cause of the X-traitor message that motivated Bishop to travel to the past.
  • The Twelve revisits The Twelve storyline introduced in X-Factor, though changing the roster of twelve mutants.
  • John Francis Moore's run on X-Force revived a number of plot threads from Fabian Nicieza's run on the series which had been dropped throughout Jeph Loeb's run. These included the true culprit for the massacre of Warpath's tribe at Camp Verde, the reason why Dani Moonstar had joined the MLF, and a proper resolution for the Reignfire story which had been cut off by Age of Apocalypse. Nicieza himself also did this in the 1999 annual, which picks up on a dangling plot thread that had been set up in the second-last issue of his run nearly five years earlier.
  • Polaris's origins danced back and forth over whether she was Magneto's daughter, until Chuck Austen's run on Uncanny X-Men made it explicit that yes, she was. But it added a new wrinkle that she'd discovered the wreckage of the plane crash that killed her mother was magnetized. However, this was forgotten about for some years, until the end of Peter David's run on X-Factor, in 2012, which finally ties up the threads, revealing Magneto wasn't the one who killed Susannah Dane, rather it was Lorna witnessing her parents having a vicious argument, which upset her enough to kick-start her Mutant powers then and there.

Comic Strips

• Calvin and Hobbes: In one storyline, Calvin needs to make a report on leaves, which he gets two aliens named Galexoid and Nebular to make for him as the price for "selling" the Earth to them. He flunks, of course. Several strips later, when winter comes, Calvin gets excited to go sledding, when Galexoid and Nebular show up at his front door, covered in snow and apparently angry over not knowing about winter being a thing on Earth. Hobbes helps by giving them his and Calvin's Christmas stockings to wear, which is all it takes to warm them up and placate them.

Films — Live-Action

• Iron Man 3 introduced the Mandarin but had him and the Ten Rings defeated, but the one-shot All Hail the King revealed that the true Mandarin is out there unhappy that Aldrich Killian used his title for his own benefit. This didn’t get followed up on for the remainder of the Infinity Saga and seemed to not be on the menu given Tony Stark’s death in Avengers: Endgame, and that the Mandarin is traditionally his nemesis. In 2021, Shang-Chi and the Legend of the Ten Rings would finally introduce the true Mandarin, Xu Wenwu, the core Ten Rings organization, and resolve the lingering subplot on Trevor Slattery.
• Star Trek II: The Wrath of Khan was all about digging up a one-episode villain from the first season of the original series and answering Kirk's question about what would happen with the "seed" that the Enterprise crew planted.

Literature

• Anita Blake: The events of book 11 resulted in the vampire serial killing group Anita was after not actually getting caught. Fans complained when the next few books didn't mention it at all, and then in Book 17 LKH went back to it and we finally get to confront the Big Bad. A few other loose threads from that were also left hanging in that book and the one right after it which are still waiting to be picked back up though.
• BIONICLE Adventures #10: Time Trap, from the end of 2005 revisits several issues that were left hanging in '04, six books earlier, such as the recovery of the lost Mask of Time and the Shadowed One's reaction to the deaths of two of his servants at the hands of Makuta. The Mask of Time plot was briefly continued in an online serial three years later.

Live-Action TV

• On Babylon 5, much of Captain Sheridan's character arc in Season 2 centers on the death of his wife and how he needs to let it go and move on with his life. Fast forward to the end of Season 3, and Anna Sheridan shows up on B5, with a message for her husband from the Shadows.
• In Breaking Bad, Marie's kleptomania is left unaddressed after Season 1, after Skyler calls her out on it. In Season 5B, Marie (now being aware that Walt is Heisenberg and Skyler is his willing accomplice), tries to take away Holly from her.
• The Brittas Empire: In Series 2, there is a recurring plotline focused on the fact that Brittas unknowingly impregnated Carole, which gets a partial resolution with Helen and Laura figuring it out but deciding not to tell either of the parents. After being briefly mentioned in Series 3's "The Stuff of Dreams" and Series 7's "http://etc", the plot point finally gets a proper resolution in "Curse of the Tiger Women", when Carole figures it out for herself and tells Helen, who then finally decides to tell Brittas about it.
• The First Evil from Buffy the Vampire Slayer makes a one-off appearance in "Amends". It shows up four seasons later as the Big Bad of Season 7. A script involving the First that they didn't use for Season 5 became the basis of the video game Buffy the Vampire Slayer: Chaos Bleeds.
• On CSI: NY, serial killer Shane Casey is introduced in episode 3.04, "Hung Out to Dry," and eludes capture for a while, but is caught and sent to a maximum security prison by the end of the season. He escapes late in season 6 and wreaks havoc again before being killed during a home invasion in the cliffhanger-finale / season 7 premiere.
• Desperate Housewives:
  • In the first season, Bree's son Andrew accidentally runs over Carlos's mother Juanita, an event that results in her death. The plot is seemingly resolved when Andrew is sent to a rehabilitation camp as punishment by his parents for his crime and various other transgressions. However, the story picks it up again when Bree and Andrew confess to Gabby in the season 6 finale. Carlos eventually learns about Andrew's involvement in his mother's death in season 7, which leads to some hostility between him and Bree.
  • In the season 1 episode "Your Fault", Lynette and Tom's plot deals with the latter's father having an affair. At some point, Tom mentions to his father something that Lynette is never supposed to know. The audience is led to believe that this has to do with Tom working with his ex-girlfriend, but we learn in the seventh season that this refers to a one-night stand Tom had with Renee Perry when he and Lynette were briefly broken up.
• Doctor Who:
  • The Third Doctor casually mentions Metebelis III in a throwaway line at the beginning of "Carnival of Monsters". In "The Green Death", he takes a quick and mostly comical trip to Metebelis III while sulking about Jo's departure, which mostly serves the purpose of giving him Green Rocks to use as a deus ex machina. "Planet of the Spiders" is set partially on Metebelis III, and it turns out the planet is extremely important in his eventual downfall.
  • The main villain of "Arc of Infinity" is revealed to be Omega, who first appeared in "The Three Doctors", which aired ten years previously. This kick-started the twentieth season, which featured a returning element from the series' past in each story.
  • "Warriors of the Deep" sees the return of two classic monsters from the Third Dotor era, the Silurians and the Sea Devils, who appeared in 1970 and 1972, respectively.
  • "Attack of the Cybermen" is one of the most continuity-heavy stories of the classic series, the plot sees the Cybermen trying to alter the events of "The Tenth Planet" and a return to the setting of "The Tomb of the Cybermen".
  • "Remembrance of the Daleks" returns to Coal Hill School and the junkyard at Totters' Lane in 1963, aka where the series began.
  • Arc Words sometimes get planted before they're even used in a this-is-leading-up-to-something fashion. We get a briefly-seen newspaper mention of "Saxon" being ahead in the polls midway through Series 2. Nothing is said of it until "Mister Saxon" becomes a mystery figure of Series 3.
  • River Song was introduced in the Tenth Doctor episode "Silence of the Library", as someone who's met the Doctor in the future. She's brought back as a recurring character in the Eleventh Doctor era.
  • There's a gag mentioned in "The End of Time" that Elizabeth I ^note A.K.A the Virgin Queen, due to getting involved with the Doctor in some fashion, is "no longer known as the...". This plot thread is used prominently in big chunks of "The Day of the Doctor", which details this involvement.
  • "Into the Dalek" deals with dropped plot points introduced in "Genesis of the Daleks", a Fourth Doctor story made way back in 1975.
  • The Series 11 episode "The Ghost Monument" has the Monster of the Week make an offhand reference to "the Timeless Child", which confuses the Doctor to said monster's amusement at her ignorance. The mystery of the Timeless Child then ends up being the main Story Arc of Series 12.
  • A Noodle Incident from the fifth Series finale "The Big Bang" - specifically the Eleventh Doctor hearing about an Egyptian goddess on the Orient Express in space - eventually became the basis of the Twelfth Doctor episode "Mummy on the Orient Express".
• Game of Thrones: Who sent the assassin after Bran Stark in "The Kingsroad" is a major Driving Question in the first half of Season 1, but while the books confirm the answer during the events adapted in Season 4, the show just lets it slide until season 7, where it's confirmed that Petyr Baelish sent the assassin. This is a change from the books, where the assassin had actually been sent by Joffrey Baratheon and Baelish only opportunistically lied about the dagger's origin by telling the Starks it belonged to Tyrion Lannister, to increase the Stark-Lannister tensions that eventually led to civil war.
• In the first season of Heroes, Hiro falls in love with a waitress named Charlie. It turns out she has a brain tumor and is going to die. Hiro accepts that he can't save her, gets some Character Development, and the plot moves on. Several seasons later, Hiro regrets that he didn't save her, and the arc focuses on her again as Hiro goes back in time to try and save her, but she gets kidnapped and held hostage by the Big Bad.
• Kamen Rider: The crossover movies are particularly fond of digging up old plot points and expanding on them.
  • The Kamen Rider ZX special was originally made to promote a TV series that never took off. It's plot would be brought back however when the villains from it return in Heisei Rider vs. Showa Rider: Kamen Rider Taisen feat. Super Sentai and try to resurrect an army of past villains to take over the world.
  • The penultimate episode of the original Kamen Rider introduced a minor character by the name of Doctor D. While he disappears not long after making his first appearance, he becomes relevant in the leadup to the Super Hero Taisen GP: Kamen Rider #3 film, where his research is used by the villains to enact their Time Travel plan.
  • Foundation X were set up early on to be the villains of the second half of franchise's Heisei era, but were gradually forgotten after Kamen Rider Fourze. They would eventually return in a special for Kamen Rider Ex-Aid, before serving as the Big Bad of the crossover film between Ex-Aid and Kamen Rider Build.
• A major plot point in the first season of Lucifer (2016) is Amenadiel attempting to coerce his brother Lucifer into returning to Hell because the place is falling apart since there's no one to rule over it. Amenadiel later has a Heel–Face Turn and the state of Hell remains unaddressed for the next several seasons until the finale of season 4 when a group of demons attempt to do the same and Lucifer is forced to leave Earth.
• NewsRadio had a storyline where Lisa decided she wanted to have a baby with Dave. This went on for a few episodes, then was quietly dropped. In a later episode the same season, there is a brief conversation about how the moment had passed. The writers hated continuing story lines, which the network continually tried to force on the show.
• In Sliders, the Kromaggs were a season two Monster of the Week who got one mention in season three. Then comes a Channel Hop... and their return as the franchise Big Bad.
• Stargate Atlantis: Stardrives were mentioned very briefly in an early episode and didn't become massively important until the finale three seasons later.
• Star Trek:
  • Star Trek: The Next Generation apparently had a policy in the writers room that they had no intention of directly following up on any characters, relatives or plot lines from the original series, as they wanted the new show to stand alone. This policy was relaxed in later years (via appearances from Sarek and Scotty), but plenty of writers were itching to follow up on some earlier stories. It wasn't until Star Trek: Deep Space Nine that they finally had a visit to the Mirror Universe from the Original Series episode "Mirror, Mirror." And from there they deliberately went in a different direction, where the Terran Empire had collapsed because of Mirror Spock's efforts to reconstruct The Empire into something better resembling The Federation. This became a Once a Season tradition.
    • Wesley Crusher is built up as being a very special person, and it is suggested that he would do something remarkable, eventually. Then he was phased out of the show, and was gone for something like three seasons. Come the final season, the Creator's Pet returns, and the plot arc completes itself.
  • Star Trek: Enterprise also did a revisit to the Mirror Universe via a two-parter taking place entirely within the Mirror Universe, no actual crossover took place. This also picked up on a episode of the Original Series "The Tholian Web" where the Enterprise sister ship Defiant was displaced by a random cosmic phenomenon. They revealed the Defiant was transported to the Mirror Universe and 100 years into the past, where different factions sought to claim it.
  • Star Trek: Discovery had their own adventure to the Mirror Universe, as their unique "spore drive" ended up taking them there by accident. Approximately 90 years after the Enterprise events (and 13 years in reality), the incident with the Defiant is even referenced and some of the plot involves trying to figure out what happened there so they could find a way to return home. It explores more of the political situation of the Mirror Universe and how they respond to the various crossings with the main universe, and reveals that the Captain Lorca of the series is from the Mirror Universe, having crossed over by accident and replaced his main universe counterpart, manipulating events so that he could return to his universe.
  • The sixth-season Next Generation episode "The Chase" revealed that the reason most aliens in the Trek universe were humanoid was due to an ancient and long-extinct race, the Progenitors, having seeded the galaxy with their DNA after discovering they were alone in the universe, a reveal which would surely have had colossal implications in-universe. While Expanded Universe material often made use of them^note  often combining them with TOS' Preservers — though that didn't make a lot of sense considering the latter were confirmed to have been active only a few centuries before, it was never mentioned again in canon... until the final season of Discovery, 31 years after their first appearance (and 800 years later in-story), where a quest to locate the technology they used to seed the universe with life becomes the subject of a season-long story arc.
• Stranger Things: Season 2 episode "The Lost Sister" reveals that Martin Brenner, the Big Bad of the first season, survived his apparent demise. This is completely unadressed for the rest of the season and the entire season 3. Brenner eventually returns in the middle of the fourth season.
• Ugly Betty had a plot arc about Amanda trying to discover the identity of her biological father. After a few episodes, the plot disappeared with no resolution. In the show's Grand Finale, Amanda finds her father, out of the blue and completely by accident.
• Veronica Mars: Veronica's rape is seemingly resolved in Season 1. She learns that she and Duncan had consensual sex while under the mutual influence of roofies, which left her with no memory, and Duncan left and never mentioned it to her because he believed she was his half-sister (which she wasn't). It then came back in a big way in Season 2, with the revelation that while she and Duncan had had consensual sex, Cassidy/Beaver Casablancas was lying about never having hurt Veronica - he raped her while she was unconscious that same night.
• The Walking Dead:
  • The mysterious helicopter that appeared throughout the first two seasons is seemingly explained early into the third season when a group of normal soldiers from the military are shown to be piloting one. Season 8 introduces another mysterious helicopter far from Atlanta (as the show has moved its setting to Virginia), one that quietly builds into a long-running subplot that eventually reveals the Greater-Scope Villain of the ensuing Walking Dead television universe.
  • The first season finale sees Dr. Edwin Jenner offhandedly mention that his French counterparts were the last scientists he spoke to before he lost contact with any other organized personnel in the world. The Stinger of the Grand Finale of The Walking Dead: World Beyond, released ten years to the day "TS-19" aired, features a French scientist watching an old recording of Jenner discussing their work together, implying the French facility may be ground zero for the walker virus and will play a key role in the unfolding Myth Arc of the franchise.
  • Morales and his family leave the group after the fish fry attack late into the first season so they can look for family in Birmingham and are never heard from again until Season 8, when Morales unexpectedly returns minus his family, who all perished early on during their journey, and having fallen in with the Saviors.
• On The Wire, McNulty's FBI buddy gives him the results of an unfinished investigation that showed Lt. Daniels was dirty when he was on the Narcotics task force. McNulty doesn't trust him for most of the first season, but eventually the men grow to respect each other. This is not mentioned again until the series finale, when now-Commissioner Daniels is forced to resign rather than be manipulated by the threat of revealing that very same investigation.

Video Games

• In Criminal Case: Mysteries of the Past, the Rochester family's corruption and evasion of justice are brought up during Elysium Fields, the game's second district, as the Arc Villain ends up being a Karma Houdini for his actions due to how powerful and influential his family is, but nothing is really resolved and the Rochesters mostly disappear from the story when you leave Elysium Fields. Twenty-four cases later, though, you reach Wolf Street, the game's seventh district and where the Rochesters officially become the main focus of the story for the next three arcs as you attempt to dismantle their corruption machine and stronghold over the city.
• Book 1 of Fire Emblem Heroes revolves around the erupting conflict between the nations of Askr and Embla, with a subplot about the Emblian royalty being influenced by a mysterious voice in their heads. The second book then has the countries establish a fragile truce while they deal with a larger threat; subsequent books continued the arrangement, with the original conflict only getting sporadic nods for several years. Eventually, Book 6 refocuses on the Askr-Embla conflict, along with confirming that the voice haunting the royal family is Lady Embla, the malevolent goddess after whom the nation is named.
  • Book 2 had Fjorm creating a pact with the unseen Lady Nifl, to gain the power to defeat Surtr; while the heroes triumphed, she was left with an Incurable Cough of Death and apparently didn't have much time to live. Despite this, Fjorm popped up in numerous later Forging Bonds conversations and paralogues, seemingly perfectly healthy; at least once she lampshades that she's baffled that she's lasted this long. Eventually, a series of Tempest Trials had Nifl finally arriving to take Fjorm's life as promised, though she agrees to dissolve the pact if Fjorm serves as her champion in a mystical battle.
• Quite a few minor plots in the earlier Mass Effect games come back in Mass Effect 3, sometimes in unexpected ways. An entire DLC of the third game, with profound revelations about the entire setting, is a Call-Back to a throwaway bit of Worldbuilding fluff text in the first game. A villain from one of the first game's DLCs can end up being recruited as an ally in the third game, and so on.
• Many of the subplots of World of Warcraft: Legion are conclusions to plot threads dropped long ago.
  • Perhaps the most notable is the return of Alleria and Turalyon. They were part of the Alliance Expedition that disappeared at the conclusion of Warcraft II. Most of the members were found during the Burning Crusade expansion of World of Warcraft, but Alleria and Turalyon were still missing. After 20 years in real life (just a few years short of the in-universe time that they were missing), their whereabouts are finally known, and where they had disappeared to forms a crucial part of the main plot.
  • Another longstanding one was the fate of Calia Menethil, the sister of Warcraft III's Arthas. She was mentioned in a novel that took place before Warcraft III and the massacre of her family and kingdom, but she was scarcely mentioned anywhere else, so her fate was uncertain. Speculation on her fate abounded, but official sources tended to ignore her altogether. In Legion, she finally returns, having escaped the fate that befell most of her kingdom.

Visual Novels

• The High School Sweetheart Ending of Melody. After not seeing Isabella since Week 5, the protagonist is with her in Week 11.

Web Original

• THE MONUMENT MYTHOS: Originally serving as the main antagonist for a single episode, the self-multiplying Alcatraz Island is never mentioned until the very ending of the next season, where it's revealed that it has consumed the entirety of America and replaced it with an exact replica of itself overnight.

Western Animation

• Avatar: The Last Airbender: One early episode introduces Bato from Katara and Sokka's father Hakoda's fleet, and suggests the kids can meet up with the fleet. When this fails, no further attempts are made to meet up with Hakoda or the fleet until the end of the second season.
• Disenchantment: At the end of Season 1, Elfo is shot and killed by a mysterious attacker. He comes back to life in season 2 and the fact the got killed, as well as the question who killed him, are seemingly forgotten, until it gets all brought up again in season 5, with Elfo finally trying to find out who his killer is.
• The Loud House: The Season 1 episode "Driving Miss Hazy" deals with Leni attempting to get her driver's license, only to fail twice. While it is briefly mentioned in the Season 5 episode "Electshunned", she doesn't bother to try her driving test again until the Season 6 episode "Driver's Dread", where she finally succeeds.
• South Park: The two-parter "Cartman's Mom Is a Dirty Slut" ended with the reveal that Liane Cartman is hermaphrodite and Eric's father but the identity of his true mother remained a mystery to his frustration. This was eventually revisited over a decade later in the season 14 two-parter "200"/"201" where it's eventually revealed that Liane isn't actually hermaphrodite and his father is Jack Tenorman.
• Star Wars: The Clone Wars was cancelled before it could follow up on Palpatine’s new scheme to clone the Zillo Beast. Thirteen years later, Star Wars: The Bad Batch finally picked up on the subplot with a newly cloned Zillo Beast debuting.
• At one point in Superman: The Animated Series, Brainiac blasts former partner Lex Luthor with a ray that (like many instances of Family-Friendly Firearms) doesn't seem to hurt him much for what appeared to be an intended killshot. In Justice League Unlimited, we find out that the blast wasn't supposed to hurt Luthor at all. Brainiac had actually implanted his data inside Lex in case he was destroyed, and this backup of himself had laid dormant for years, subtly influencing Luthor until he fully activated and took over. The creators have said that they'd actually planned it the day they wrote the scene from Superman, but didn't have the right opportunity to use it for a while. Lucky for them the DCAU lasted long enough to do it.
• In Transformers: Animated, Porter C. Powell makes a single not-terribly-memorable appearance in the first season and it doesn't look like he's intended to return. In season two, he comes back with a vengeance, usurping control of Sumdac Systems when Isaac Sumdac goes missing.
• Transformers: Prime:
  • Unicron first appears and is dealt with at the end of season 1. After being mostly forgotten for the following two seasons, he reappears to follow up on his plans in the series finale movie Predacons Rising.
  • The synthetic Energon formula is teased to return at the end of "Stronger, Faster", but it goes completely unmentioned until the Season 3 episode "Project Predacon" when Ratchet decides to revisit the project. Even then, it doesn’t make a proper comeback until a few episodes later in "Thirst", becoming a critical element of the show’s final arc.

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