In a desperate move to stop Savitar, Barry travels into the future where he sees the long-term effects his decisions will bring.
Tropes
- Achilles in His Tent: Future Barry finally jumps back into action when his past self is in mortal danger.
- All for Nothing: Barry finds out his future self never learned Savitar's real name, thus losing the original reason he came to the future, although he does learn how Future Barry trapped Savitar in the Speed Force.
- An Arm and a Leg: At some point, Killer Frost destroyed Cisco's hands, leaving him to use robotic replacements.
- Bad Future: Barry is shown to have landed in this when he goes to 2024, due to Iris being long dead, and nobody's in good shape:
- Barry is a recluse hiding in the now fully derelict S.T.A.R. Labs, morbidly obsessing over his failure to save Iris.
- Cisco lost his hands in his fight with Killer Frost, and with them his ability to use his powers.
- Killer Frost, who knows Savitar's identity but is unwilling to reveal it, is locked up in Iron Heights with Julian as her caretaker.
- Wally is confined to a wheelchair and catatonic as a result of taking Savitar one-on-one in a fit of rage after his sister's death.
- Joe is a broken man, his family in shreds, and resents Barry for abandoning him.
- H.R. is the only one not having a bad time, having achieved considerable success as a romantic novelist. And he now owns Jitters.
- Brick Joke: While celebrating the reunion of (most of) Team Flash as well as victory over the Mirror Master and the Top, Joe ponders which Barry he should hug first, and the present Barry points towards his future self. When Barry returns to the present time, one of the first things he does is give Joe a hug.
- Additionally, Future H.R. signified Team Flash coming back together by everyone putting their hands together in a circle. He tries this in the present, only for everyone to dismiss it.
- The Bus Came Back: Sam Scudder and Rosa Dillon are on the loose again and give 2017 Barry a beatdown at one point. Fortunately, he has help when he faces them the second time.
- Call-Back: Future Barry, while in seclusion in the Time Vault, learns of his past self rallying the Team back together, most likely thanks to Eobard Thawne's surveillance system.
- Career-Ending Injury:
- Caitlin destroys Cisco's arms, effectively ending his superhero career by 2024, since he can't access his powers with his prosthetic hands. Barry promises him that he'll prevent that from happening.
- Wally ends up with permanent paralysis, as he tried to take on Savitar himself and lacks Barry's Healing Factor.
- Character Check: How do we know the Present Flash's spirits have been lifted? He starts talking smack to his rogues.
- Chekhov's Gunman:
- Tracy Brand, the physicist who designed the trap that allowed Barry to capture Savitar in the Speed Force.
- Future Barry mentions that one of the gambits he used to try to save Iris was creating time remnants of himself, only for Savitar to kill most of them; there could still be a few out there.
- Chronic Hero Syndrome: When push comes to shove, Barry just can't abandon the Bad Future without trying to fix it. This ends up inspiring his future self to make a difference again. Cisco invokes this trope.
- Color Wash: The future scenes have a jade tint to it, reflecting its bleak atmosphere.
- Despair Event Horizon: Everybody but H.R. and Cisco crosses it in the future.
- Didn't Think This Through: Trying to hide from Killer Frost, Cisco, H.R. and Julian hide in the Pipeline. They forget that she knows how to open the door.
- Dirty Old Man: Assuming that all the Harrison Wellses were born on the same date as their actor, then 2024 H.R. is still gladly fooling around with several young women at 60.Explanation
- Double-Meaning Title: "The Once and Future Flash" refers to Future Barry, who is essentially retired due to being reclusive over grieving Iris' death. The title could also be interpreted in Name and Name style with "the Once Flash" being present day Barry, due to being set in the Bad Future, and "the Future Flash" obviously being that time's Barry.
- Earn Your Happy Ending: Well, "happy ending" is certainly a stretch, but the ending of this episode seems to imply that even if Iris is killed, the worst-case scenario is that Barry wallows in misery for seven to eight years before being inspired by his younger self to put the costume back on, mend his relationships with Team Flash, and move forward to a new heroic era as the Flash in what seems to be a Hope Spot for where the Bad Future is headed.
- Evil Former Friend: The 2024 Killer Frost is an ally of Savitar. Present day Barry is determined to avert this by the time he goes back.
- Expendable Clone: Future Barry recounts how he tried to use time remnants of himself to save Iris, only for Savitar to kill most of them.
- Freudian Slip: During the Expo with his very enamored fans, H.R. says they should do a threesome, which earns him a chuckle from his audience before he has a Verbal Backspace.
- Funny Background Event: At the end of the episode when H.R. was suggesting Team Flash put their hands together, no one takes him up on the gesture except (and only at the last moment) Wally. And H.R. has already given up even before Wally could put his hand in.
- Future Badass: According to Aaron Helbing, 2024 Mirror Master and 2024 Top are considerably more powerful than their fall 2016 selves. They certainly give Barry a hard time until his future self shows up to help him.
- Heroic BSoD: Wally has been catatonic and stuck in a wheelchair ever since his failed battle with Savitar. It's implied that he saw something to make him Go Mad from the Revelation, possibly Savitar's true identity.
- He's Back!: After spending the whole episode (more like the last seven or eight years in-universe) wallowing in grief over Iris, Future Barry is inspired to help his past self in the field, even donning his classic costume at last.
- Hope Bringer: Future Cisco was banking on the Present Flash becoming this for Central City and especially Team Flash to knock them out of their grief and return to action. In the end, not only does it work, even the Future Flash is inspired enough that he winds up trying to give his past self an actual advantage against Savitar, even if by little.
- I Hate Past Me: Future Barry is...not overjoyed to see his past self, to say the least. The feeling winds up being mutual, as 2017 Barry chews him out for wallowing in grief over Iris and pushing everyone else he loves away. By the end, Future Barry has come around enough to help.
- Indy Hat Roll: H.R., complete with a grab for one of his drumsticks.
- Idiot Ball:
- Lampshaded by Killer Frost when Cisco, H.R. and Julian try to hide from her in the Pipeline, and just behind the main door; they could at least have gone further in.
Frost: Hey, dummies. My palm scan still works.- Barry rushes in to save Cisco, H.R. and Julian and tries to talk Killer Frost down instead of putting her into a cell. In fairness, that did actually work last time, but he really should've been more careful.
- The Top's powers can affect anyone within her line of sight. Barry, who is capable of moving faster than the eye can follow, pulls up to a complete stop directly in front of her.
- Internal Reveal: Killer Frost finds out who Savitar is...while the audience doesn't. However, the promo for next week hints that Barry finally figures it out on his own.
- Ironic Episode Title: The episode title fits really well with the succeeding episode (which will not be tackled here).
- Irony:
- Scudder has no qualms calling Central City "his town", with Dillon snidely correcting him with "our town". Captain Cold, Scudder's rival, and Heatwave have the same exchange in Season 1's "Rogue Time", only replace town with city.
- The Flash suit of the present day Barry, who has a brighter outlook in life, has darker shade compared to the jaded Bad Future Barry's which is bright red with golden accents.
- It Only Works Once: Barry tries to talk to Killer Frost just like he did last time to get Caitlin back. Unfortunately, Killer Frost is in complete control this time so she really doesn't care.
- Kiss of Death: Killer Frost is about to do this to Julian, but Cisco stops her.
- Knight in Sour Armor: 2024 Cisco's outlook in life barely soured despite everything that has happened.
- Leaning on the Fourth Wall: The much-criticized Poor Communication Kills and Aesop Amnesia of keeping secrets from each other that has plagued not just Team Flash but basically every Arrowverse show is gloriously lampshaded by Killer Frost when she learns that 2024 Team Flash is keeping 2017 Barry in the dark on a few details.Frost: (smirks) Well, I guess keeping secrets always was our thing.
- The Lost Lenore: Iris for Future Barry. Iris West is/was the love of Barry Allen's life, and he fell into such despair over her death that he couldn't keep his promise to be their for the rest of their friends and family.
- Meaningful Release Date: Possibly coincidental, but this episode has Barry travel to the year 2024, and aired on April 25th, 2017. Eobard Thawne's newspaper from the future (which is still in the time vault) is from April 25th, 2024, and says that the Flash will vanish during the "Red Skies" crisis. However, this episode itself takes place on February 3, 2024, two and a half months before that fateful night.
- Menacing Stroll: Caitlin as Killer Frost takes one when she chases after H.R., Julian and Cisco.
- My Future Self and Me: Barry finally meets his 2024 self, who's been ridden with guilt over Iris dying.
- Mythology Gag:
- After three seasons of teases, Future Barry is confirmed to wear the New 52 version of his classic costume, with a much brighter and deeper shade of red, solid golden earpieces, a golden lightning belt, and golden lightning cuffs for his arms and boots, in lieu of the iconic fully golden boots. It also has more of a solid leather look than his current suit.
- The Bad Future bears some similarities to a storyline in the New 52 featuring an evil Future Flash (Barry gone off the deep end). While in the comics version, Wally is long dead and Iris is in a wheelchair, it's the other way around here.
- Cisco's robotic hands may be a reference to the fate of his comics counterpart. Back during the infamous Justice League Detroit era, when Vibe was an Ethnic Scrappy, his career as a superhero met a grisly end when he was brutally strangled to death by the robotic hands of Professor Ivo. Needless to say, Alas, Poor Scrappy was felt by even his harshest of critics.
- Future Wally's caretaker/implied wife is an Asian woman. In the comics, Wally is married to Korean-American Linda Park.
- The episode's plot is similar to an episode of the Teen Titans cartoon where a protagonist (Starfire/Barry) travels to a Bad Future and meet friends who are now incarcerated due to being dangerous (Future Raven/Future Killer Frost), physically handicapped (Future Cyborg/Future Cisco and Future Wally), suffering from severe depression (Future Beast Boy/Future Barry and Future Joe) and one who still holds on to a hope that the gang will reunite (Future Robin aka Nightwing/Future Cisco and Future H.R.).
- Name and Name: The title respectively refers to present day Barry and Bad Future Barry.
- Nice Job Breaking It, Hero: Cisco accuses Julian of being responsible for Caitlin becoming Killer Frost by not taking her to a hospital and going against her wishes.
- Oh, Crap!: Top and Mirror Master immediately try to run away when they see two Flashes and realize their powers are disabled. Which goes as well as you'd expect.
- Older Than They Look: Everyone has barely aged in 2024 despite Bad Future Joe telling 2017 Barry that he looks young.
- The Pollyanna: Future Cisco still has some optimism in him despite all that has happened.
- Putting the Band Back Together: Barry puts the remains of Team Flash together, and eventually his future self gets out of his funk, too.
- Pyrrhic Victory: How Future Barry describes his defeat of Savitar — Savitar had already won by destroying Team Flash, especially since Barry had to wait for four years after Iris was killed before he could trap him in the Speed Force because he had to wait for the technology to develop.
- Revenge Before Reason: Future Wally literally rages on Savitar after the latter kills his sister. As Wally did not take into account the power gap between them, Savitar utterly destroyed him in their fight, which directly lead to his Career-Ending Injury.
- Screw Destiny: At the end of the episode, Future Barry gives our Barry an info disk detailing the trap to catch Savitar, designed by a physicist named Tracy Brand, hoping his past self can have it built sooner instead of the four years he had to wait for it.
- Shout-Out: The title "The Once and Future Flash" is a reference to issue #79 of The Flash vol. 2, itself a play on the classic Arthurian novel The Once and Future King.
- Skewed Priorities: When the holding cell closes in which H.R., Cisco and Julian try to hide from Killer Frost, H.R. reaches out for one of his dropped drumsticks. Also somewhat in the future, where he searches for them when Barry goes up against Top and Mirror Master.
- Spoiler Title: The episode title is a giant Foreshadowing of a major reveal next episode.
- Stealth Sequel: To the Legends of Tomorrow episode, Star City 2046, which also depicted what's left of Team Arrow in a Bad Future.
- Stepford Smiler: It's implied that Future Cisco is this. While he still seems hopeful despite the West family falling apart and he himself losing his friend Caitlin and his hands (with the use of his powers) to Killer Frost, the way he's messily dressed suggests that on the inside, he's just as depressed as everyone else.
- Tailor-Made Prison: Julian has Killer Frost in a prison similar to those in the Particle Accelerator.
- The Stinger: Savitar comes to Killer Frost to forge an alliance, and to get her to trust him, he opens his armor and reveals himself to her...just not to us yet.
- That Man Is Dead: Everyone is quick to make the distinction between Killer Frost and Caitlin, claiming Killer Frost took her.
- Trailers Always Spoil: Future Barry getting out of his funk and back into action has been blatantly shown in the episode's trailer.
- The Un-Reveal: In The Stinger, Killer Frost goes to the woods, where she meets Savitar. They talk for a bit, with Savitar promising her great fortune should she serve him. When she asks why she should trust him, he kneels as his suit slowly peels open, steps out into the snow clad in black, and we don't see his face or hear his real voice. While Killer Frost's reaction implies recognition, the audience is still left in the dark. She's the only one (aside possibly from the catatonic Wally) who knows who he is in the future, either.
- Vice City: In the Bad Future, Central City has become a harbor for supervillains due to the Flash's absence.
- Villain Team-Up: After she got loose, Killer Frost teamed up with Savitar, who "cured" her by getting her to embrace her darkness.
- What the Hell, Hero?:
- Cisco really gives it to Julian for removing Caitlin's necklace against her wishes.
- Present Barry chews out his future self for abandoning his friends and family when they needed him the most, especially when Iris had him promise that he would look after them if she died.
- Writers Cannot Do Math: Barry travels from 2017 to 2024, which is a gap of seven years. However, Barry constantly refers to 2024 as being eight years in the future for him. It's not even a case of him rounding it upwards — Barry departs from early 2017 (when the episode airs) and arrives in February 2024, which is a gap of seven years, probably even a little less!
- Year Outside, Hour Inside: Once again, Barry returns to the present mere seconds after he left, despite staying in the future for quite some time.
- You Can't Fight Fate: Future Barry believes this, as he flat-out tells Barry that nothing he tried to save Iris worked, so he should just accept her death and focus on spending time with her. He changes his mind at the end, though.
- You Wouldn't Believe Me If I Told You: Future Killer Frost doesn't tell present Barry who is Savitar and only tells Barry that he would be surprised if he knew.
