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Never the Selves Shall Meet

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"Alright, this next test may involve trace amounts of Time Travel. So, word of advice: if you meet yourself on the testing track, don't make eye contact. Lab boys tell me that'll wipe out time. Entirely. Forward and backward. So do both of yourselves a favor and just let that handsome devil go about his business."
Cave Johnson, Aperture Science CEO, Portal 2

For some reason, encountering yourself — whether as a time-traveler or in Another Dimension — is frequently Very Bad; either it's unhealthy for you in particular, or it creates a Temporal Paradox.

This may result from attempts to apply causality to time travel: you can't meet a past version of yourself without having memory of it and the future version of yourself cannot be surprised to see past you, having had to be there to see it to make it possible. However, this can be easily avoided if you fail to recognize yourself, such as through an Alternative-Self Name-Change. As a result it's generally correlated with time travel of the Timey-Wimey Ball variety, and negatively correlated with Stable Time Loops (though there are exceptions). Compare Future Me Scares Me; contrast Screw Yourself.

Alternatively, the show might say that you're both made out of the exact same atoms, and the universe gets wonky when you have matter touching itself.

Note that this trope is now so well known that movies which use Time travel often only throw out a one-liner warning: "Whatever you do, don't meet up with yourself!" It's now becoming a trope in and of itself to make the reason for not meeting up not a dire end-of-the-world reason, but merely for convenience of the Master Plan. These often result in My Future Self and Me.

A closely related trope is Only One Me Allowed Right Now. Contrast Future Self Reveal.


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    Anime & Manga 
  • Haruhi Suzumiya:
    • Future selves take great care to conceal themselves from past selves who didn't see their own future selves. However, they also take just as much care to reveal themselves to past selves who remember seeing or hearing their future selves. Basically, future selves act so that their past self experiences events as their future self remembers them.
    • Future Asahina conceals herself from her past self on most occasions, with the explanation that her past self didn't see her future self. The one exception is when Kyon, Asahina (small) and Nagato go back to December 18th to save the world; Asahina (small) sees Asahina (big), but doesn't recognize her, and doesn't pay her much attention. There are slightly more important happenings going on, like, y'know, Kyon bleeding to death in the middle of the street.
    • In The Disappearance of Haruhi Suzumiya we see Present Kyon hide so as not to reveal himself to Past Kyon from "Bamboo Leaf Rhapsody," who he remembers didn't see him; but towards the end, when Kyon gets stabbed, his future self arrives and tells him some words before he passes out. After he wakes up, Kyon recognizes that the voice he heard was his future self, and that when he travels back in time to that day again, he must tell those words to his past self.
  • Doctor Slump — it's a Gag Series, after all.
    • Averted when Senbei uses his Time Skipper to go back in time (three days in the past) to meet his past self in order to gain an insight on how to repair Arale.note 
    • Parodied when Obotchaman uses the Time Machine he borrows from Turbo to find out what happens to himself and Arale ten years from now. There's no inherent danger in meeting his future self, but he still does his best to keep it on the down-low to avoid weirding his future self out. Luckily, his future self is at home and never sees him.note 
    • Parodied again when Tori-bot uses the selfsame Time Machine to visit Penguin Village ten years from now and find out what becomes of his future self near the end of his travel. Again, there's no inherent danger in meeting his future self on its own, but his experience bums him out when he discovers that his future self turns out to be a panhandler begging for money at the street-side.
  • In the Dragon Ball Z special "Gather Together! Goku's World" that was released for the Terebikko, Goku meets with his younger self when the gang were time traveling. Trunks stops Goku from interacting with his younger self to prevent a paradox.
  • Averted in Doraemon, where Doraemon and Nobita interact with the latter's future self on numerous occasions. In one episode, the future Nobita had to stop his past self from cheating on a test!
  • In the manga version of Sailor Moon and in Sailor Moon Crystal, during the Time Travel to the thirtieth century, the titular character feels faint in the presence of her future self, Neo-Queen Serenity, and her body becomes transparent; her Silver Crystal also loses its power under the influence of its future counterpart. At the end of this story arc, Neo-Queen Serenity tries to resist the temptation of talking to her past self, since it may result in the history being changed... fails, and goes to meet Sailor Moon anyway for some seconds. The story also involved Prince Demand attempting to bring the world to an end by bringing together the two Silver Crystals, which is stopped by Pluto stopping time at the cost of her own life. Interestingly, in Stars it appears that the selves can meet, if one of them is (supposedly) from an alternate distant future and in disguise.
  • Rascal Does Not Dream of Bunny Girl Senpai: Futaba realizes that the scarring on Sakuta's chest only manifests when the mature Shoko is around. This is because Future Shoko has Sakuta's heart, and the two hearts being in the same place is causing problems for the first one.
  • Played straight in Kimagure Orange Road. Touching one's past self will cause the future version to dissolve. It's never really explained exactly what happens to the future self but it gets shelved under "a bad idea to try". It almost happens to Madoka in the TV series, when she befriends her younger self during an accidental trip to the past, but right when little Madoka and big Madoka are about to shake hands, little Madoka's big sister calls out to her and they don't touch.
  • Played with quite a bit in Negima! Magister Negi Magi during the Mahorafest arc. The aim is to not let the selves meet, but often the later selves run into the earlier selves, and at times, a character runs into one version of a character almost immediately after leaving another version of the character, causing confusion—especially when it happens with one of the girls not in on the Masquerade. Also, at one point, we distinctly see two Chamo-kuns meeting up and high-fiving. And then switching places! How that's supposed to work is mind-boggling.
  • Natsu no Arashi! firmly enforces this. People start to fade when they get close to their past selves, and if you meet yourself, you'll vanish entirely. Time doesn't like people having two of themselves in one place.
  • In Black God, every person has two doppelgangers. When they meet two of the three wither away, but the third will thrive at the cost of the others.
  • Reborn! (2004):
    • Lambo's 10-year Bazooka doesn't usually age him up — it temporarily switches him out with his future self.
    • Played with in the Future arc. It's revealed that Shouichi Irie trapped the future Vongola in the White Round Time Machine to keep them from switching out with their past selves, meaning they're still in the same time period for the duration of the arc. However, because of the same machine, they don't directly interact.
    • An attempt to Defy this trope by Byakuran resulted in the creation of Ghost, who was an Alternate Self that was brought over to the main timeline with the Millefiore's tech. In the process, Ghost's own parallel world was destroyed, and Ghost himself was left as a Flame-absorbing Humanoid Abomination with hardly anything resembling a human consciousness. When the flames that compose him were finally absorbed, they went directly to Byakuran.
  • Occult Academy goes for the worst possible variation. Fumiaki meeting his past self overloads the timeline and causes the apocalypse. Though he does Screw Destiny and prevents the thing he caused.
  • JoJo's Bizarre Adventure:
    • Steel Ball Run: This is applied to versions of people and objects from parallel universes. Dirty Deeds Done Dirt Cheap, the Stand of the Big Bad Funny Valentine, specifically protects him from the effects of this, but also allows him to use it against his enemies. Even after his defeat, the final enemy an alternate Diego Brando still meets his end through this rule courtesy of Lucy Steel and the decapitated head of the main universe Diego.
    • This is actually used in the All-Star Battle video game as the character's strongest attack - he summons a version of his opponent from another universe, and then throws the two of them into each other, causing both to detonate.
    • Eyes Of Heaven zigzags this, as the story has the young Joseph Joestar from Battle Tendency meeting up with his older self from Stardust Crusaders, yet nothing comes of it. When the group encounters Funny Valentine and he demonstrates this fact with a gun Johnny Joestar was hiding, young Joseph points out he came in contact with his older self but didn't disappear. Funny Valentine explains that it only applies to people from different universes, not to people from different points of time.
  • In Yu-Gi-Oh! ARC-V, whenever two of the four Dragon Boys (Yuya, Yuto, Yugo and Yuri) are in close proximity to each other and to Yuzu, one of the Dragon Boys is forcibly teleported away to another dimension. This trope is intentionally invoked on the Dragon boys to prevent the rebirth of Zarc, the Big Bad of ARC-V.
  • In The Vertical World, meeting yourself doesn't affect the universe, but it does cause both versions of you to "collapse" into one, sometimes causing your memories to merge as well.
  • Semelparous deals with a Secret War waged between parallel universes. The Alternate Universe has all the same people as the prime universe, but normally the walls between the worlds keep the death of one from affecting the other. However, if they die in the Void Between the Worlds, so does their counterpart: it takes two walls to fully isolate the counterparts from each other—and the kaiju are made from humans, meaning every time the Bulwarks kill a kaiju, somebody in our world dies. The mures of the other world weaponize this, making kaiju out of the doubles of friends and family of the Bulwarks to psychologically torture them, and, when possible, the Bulwarks themselves, to ensure a kill.

    Comic Books 
  • Wonder Woman (1942): An old Silver Age story involves Wonder Girl (Wonder Woman as a girl, before she became a separate character) attempting to meet her adult self but failing; this is the reason given for the failure. Later, it's why there needs to be a Hand Wave ("Amazon magic") for why Wonder Girl and Wonder Tot (Wonder Woman as a toddler) are able to team up with the adult Wonder Woman.
  • Superman:
    • Some stories have time travelers turn into phantoms if they arrive somewhen they already exist.
    • A memorable use of this concept occurs in Whatever Happened to the Man of Tomorrow?, when a young Supergirl has traveled to the story's present (which is shortly after her death in Crisis on Infinite Earths), and casually asks her cousin why this hasn't happened.
      Superman: (looking away) Right now Supergirl is... in the past.
    • In most Silver Age Superman stories, if the Man of Steel travels to a time, past or future, where he exists, that other version gets tossed back to the "empty slot" he started from. This normally occurs in Superboy stories, so that Superman ends up wandering the Smallville of his youth.
    • In A Mind-Switch in Time, Superman and his younger self attempt to time-travel at the same time and collide with each other. Since nobody, not even Pre-Crisis Superman, can co-exist with himself at the same time, each one is tossed back to their own time, but with their minds swapped.
    • In the Final Crisis: Legion of 3 Worlds miniseries, Superboy-Prime punches his future self, causing both selves to dematerialize and disappear.
    • In Final Crisis: Superman Beyond it was claimed that Superman and his Mirror Universe counterpart, Ultraman, can't touch each other without causing an explosion that would destroy them both. Except in Limbo, where the rules are different. (Never mind that they've fought each other lots of times and that's never happened before.)
    • Also, the first time Post-Crisis Supergirl met Power Girl, shaking her hand caused Power Girl to suddenly go berserk and attack everyone. This was attributed to them being alternate universe counterparts and it making reality glitch out for a moment or something, but it hasn't happened since.
    • In Supergirl (2011) issue #19, Supergirl and Power Girl meet up again with very different results, providing both a discussion/lampshading and subversion of this trope. It turns out Power Girl knew about the main DC Earth's version of Supergirl but didn't dare because she didn't want "the universe to explode if we touch." (What actually happens when they do touch is that they exchange memories.)
    • Although Waverider of Armageddon 2001 had encountered his younger self as Matthew Ryder in 1991 without any problems, realizing from this that he was the superhero he met as a child who rescued him, he was tempted to make himself fully known to both his younger self and his parents in the Superman story "Time And Time Again Again", but he didn't because he realized that would disrupt events in the space-time continuum. He did, however, meet with his alternate timeline self as the leader of the Linear Men, which at first turned out to be disastrous since when Waverider killed the other Matthew Ryder, he trapped himself, Superman, and the Linear Men in a Nullsphere, unable to leave until Waverider used Hunter's energy beam to alter time so that the other Matthew Ryder was never killed in the first place.
  • In Crisis on Infinite Earths, it becomes Never the Earths Shall Meet, as when the universes of Earths-1 and 2 are shunted into the Netherverse, they start slowly merging with each other, with the Monitor explaining that if they should occupy the same space together, they will annihilate each other. The result of this merging is that all time becomes one, creating a "warp zone" between the Earths where all of Earth's history is mixed together in a strange hodgepodge. The universes of Earths-4, S, and X also share the same problem, although the heroes realize that it is the Anti-Monitor that is causing the universes to merge together toward the end of mutual annihilation. It isn't until after the battle with the Anti-Monitor at the dawn of time that the multiple universes are safely merged together and rebooted as a single universe.
  • In Timecop, you can meet yourself and even talk to yourself, as long as you do not touch, because "the same matter can't occupy the same space at the same time". When the Big Bad does (with the hero's "help"), both selves melt and are erased from time.
  • Subverted in an issue of Iron Man when Doctor Doom travels to the future to meet himself. When Doom notes the theory, his elder self snorts that whoever came up with it never actually time-traveled.
  • Major Victory of the Marvel Universe (specifically the 31st Century's Guardians of the Galaxy), after he travels back to the present, has to be careful about this with his shield, since it's Captain America's from the future; it's established that if the present and future shields ever make contact, Bad Things will happen. Oddly, this is not a problem when he meets his younger self.
    • Major Vance Astro, in fact, sought out the younger Vance Astrovik to explicitly tell his younger self not to become an astronaut, thus avoiding the Bad Future of the Major's Alternate Timeline. As a result of the meeting, the younger Astrovik's powers developed early, and he went on to become Justice of the New Warriors.
  • One Wolverine comic involves Jubilee (Marvel Comics) going back in time. Her past self temporarily disappears.
  • One version of the death of Justice Society of America villain Per Degaton (who was split into two versions — one taking The Slow Path, the other gaining access to a Time Machine — in 1947) has him being disintegrated when he and his "chronal duplicate" finally meet up in the 1980s. This happened in an Infinity, Inc. annual in 1988 that retells the fate of Professor Malachi Zee due to the events of America vs. the Justice Society not happening in the Post-Crisis DC Universe.
  • In one anniversary edition of Spider-Man involving Doctor Strange, Spidey was successfully able to see his past self (right before being bitten by the spider) and listen to advice from his future self on what seemed to be the end of his career (right before his future self is gunned down by the police for some unknown crime). Of course, seeing as the reason he was seeing this was because the fabric of reality was already in jeopardy because of Dormammu's plot to bring about the apocalypse, it's likely these two encounters couldn't have done any further damage.
  • Winx Club: The comic book version has a story where the Winx girls travel to the future. The scientist who invented the Time Machine discourages them from meeting their future selves because of this trope.
  • Fantastic Four:
    • Sue Richards actually asks this when Franklin and a version of himself from the future are talking. The older Franklin, and his father Reed, stare at Sue like she asked the dumbest question ever. This is after young and old Franklin have interacted for a good long while, by the way.
      Future Franklin: "However, if I stay any longer, there are going to be repercussions."
      Sue: "Okay... is this a paradox thing? Like two of the same object can't occupy the same space-time or the entire universe will implode... or something?"
      Both Reed and Future Franklin: (Deadpan) "That's not how it works."
    • Though Franklin explains that the danger does have to do with both Franklins being in the same time, but it has to do with the universe being sentient and potentially freaking out if it became aware of two Franklins coexisting.
  • My Little Pony: Friendship Is Magic (IDW) has an entire arc exploring the risks of this. Having too many counterparts in one universe throws off the balance between them, disrupting both and causing a Reality Bleed.
  • Invoked in Adventures of the Super Sons. When Jon is split into a red and blue version of himself by red kryptonite, Damian knocks their heads into each other in an attempt to make them whole again. All it does is get both Jons to complain.
    Damian: And can't you guys just... I don't know... absorb each other or something?
    Red and Blue Jon: [simultaneously] Ow! Stop it! That's not how it works!
  • The Grim Adventures of Billy & Mandy story "Better Luck Next Time" has Billy and Mandy sucked into Grim's cosmic cuckoo clock and sent hurtling through time where they run into a mysterious cloaked figure who warns them to never meet themselves as they effort to journey back to their own time and place. Not because of any disruptive anomaly, but because the cloaked figure couldn't stand being around more than one of them to start with (giving away that the cloaked figure was actually Grim way into the future).
  • In Star Trek: The Next Generation/Doctor Who: Assimilation², the Doctor has to go back to when Picard had been assimilated by the Borg. He tells Picard he has to stay as two versions of himself can't exist in the same timeline. As soon as the TARDIS leaves, Amy points out how she and Rory have met past/future versions of themselves already. The Doctor admits he was lying because he doesn't want Picard to go through the experience of seeing himself as a Borg again.

    Comic Strips 
  • When Maria first revealed herself as a time traveler in Safe Havens, she said that this was why it took her two days to pick up her time-displaced son Leonardo da Vinci, because she already existed in those days. As to an explanation as to how she was able to be born in this timeline when the older Maria was already here — delivered by the older Maria, no less — she merely says "life finds a way".

    Fan Works 
  • Exploited in Jonathan Joestar, The First JoJo. While in Cairo, Jotaro and Jonathan find a pair of DIO's bracelets. During the final battle, they come into contact with Heaven Ascension Dio's own bracelets in order to stop him from using The World Over Heaven's ability.
  • Discussed in Spectacular Seven. Sunset Shimmer eventually meets her human counterpart, going under the alias Snake Queen Lamia. Once the two figure out that they're each other's counterpart, they try to avoid making contact for fear that "the universe might explode." The two of them do eventually make contact, but all it does is allow each Sunset to briefly see the other's memories. In the "Phoenix Rising" chapter, Sunset does this again when Lamia is under the effects of Demonic Possession to regain her own memories, free Lamia, and fight off Moondancer.
  • In Carpe Noctem, a Harry Potter fanfiction, because Hermione accidentally lets her past self see her future self while time-traveling, a disruption in the space-time continuum occurs.
  • In Memento Vivere, a Final Fantasy X fanfiction, Rikku deals with this by avoiding Bikanel.
  • Around the time Titanic (1997) came out, a lot of Doctor Who fanfics got written with the Doctor and co. visiting the doomed ship. One fanfic lampshades this by having the TARDIS appear on the Titanic only for the Doctor to moan, "Oh not again!" His companions look around and notice that a large percentage of the passengers are different versions of the Doctor and his various companions. "The TARDIS just seems to like the North Atlantic," he sighs.
  • There was a My Little Pony: Friendship Is Magic fanfic which involved Rainbow Dash travelling in time to set herself and Applejack up. Eventually, because of this, she, Applejack, and Twilight Sparkle are all jumping through time trying to make sure the right versions of themselves meet at the right time. It ends up with several dozen of each pony getting very confused. And then Scootaloo gets caught up too...
  • In On a Cross and Arrow, there's dimensional travel replacing time travel. Twilight ended up accidentally sending the Mane Six into an alternate dimension where everyone is gender-swapped versions of themselves. She feared that if they met their alternate selves, they would explode or something. Thankfully, this isn't the case in the slightest.
  • In the Pony POV Series, during the Dark World arc when Twilight meets Minty Pie, there's a variation where both of them are reincarnations of G3 Minty note . Due to this unusual variation, they're able to interact fine, without any problems, but when they make physical contact they start to fuse together which pretty much Mind Rapes them both. Fortunately, they break apart in time to avoid anything permanent, and while shaken, they're fine afterwards.
  • In The Twilight Child, when a pony named Comet Chaser meets a version of himself from roughly twenty years into the future... nothing happens to them, but it is as amazingly awkward as it could possibly be.
  • The Volatileverse explains reality cannot handle two people having the same aura signature without growing unstable. Jason Todd was able to cross dimensions and stay in another Earth than his because his counterpart was dead.

    Films — Animation 
  • In Mr. Peabody & Sherman, Mr. Peabody warns Sherman not to travel to a timeline where you already exist. It turns out this is because two people from different timelines touching each other causes a potentially-catastrophic Reality-Breaking Paradox.
  • Zigzagged in the Minions movie, where Bob encounters a German time traveler named Professor Flux who brings his future self back from the future to help him every time he visits the future. However, as the Professor Flux from "two weeks from now" is asked to move a part, he accidentally hits the original, causing him to break his neck and the other Fluxes to disappear from existence.
  • Yellow Submarine has the Beatles and Old Fred traveling through the Sea of Time, at first regressing to childhood (young adulthood in Old Fred's case), which John corrects by moving the hands of the Sub's clock forwards. As the team progresses, they see an identical yellow submarine with similar passengers:
    Paul: Funny...a submarine remarkably like our own.
    John: Uncannily.
    Ringo: There's someone in it. Look.
    George: And they're waving.
    Ringo: It's a group of fellas.
    Paul: Wave back. (they do)
    George: Maybe we're both part of a vast yellow submarine fleet.
    Ringo: There's only two of us.
    John: Well, then I would suggest that yonder yellow submarine is none other than ourselves...
    Old Fred: Going backwards...
    John: In time.
  • Averted in Meet the Robinsons at the end where Lewis meets his future self Cornelius Robinson, they even touch and nothing bad ever happens. The same applies when Goob unknowingly encounters his future self, The Bowler Hat Guy.
  • Zigzagged throughout the My Little Pony: Equestria Girls franchise.
    • Twilight Sparkle's pony friends offer to follow her through the portal in My Little Pony: Equestria Girls – Rainbow Rocks but she refuses, trying to avoid this trope, although it's not actually dangerous to meet your counterpart, so much as it's really awkward.
    • In My Little Pony: Equestria Girls – Friendship Games, Pony Twilight accidentally victimizes herself to the trope in The Stinger when she steps through the portal after a long absence and meets her human counterpart face-to-face.
    • Happens again in My Little Pony: Equestria Girls – Spring Breakdown when Sunset, Human Twilight, and Human Rainbow Dash accidentally find a portal to Equestria. While the party takes pains to avoid Pony Rainbow Dash, they do meet Pony Twilight, leading to the two interacting. Once again, this is not due to any potential danger, but rather to avoid attracting attention to themselves, which in turn justifies them averting this trope with Princess Twilight due to already being friends with her.

    Films — Live-Action 
  • Back to the Future. Probably the Trope Codifier in film, despite the trope being less a hard and fast rule and more of a general guideline.
    • In the movies, nothing worse than fainting happens, and both Doc and Biff seem able to avoid even that by averting their eyes from themselves, or maybe just by being prepared for it. It seems that young Biff in the '50s had no basis to suspect that the "crazy old codger" was himself. It's also entirely possible that the "destroy the universe by temporal paradox" hypothesis was just that — a hypothesis, and there never was any real danger at all. The two Bobs explain that Doc's concern is that the recognition of a past character meeting his or her future self could lead to an event that causes the paradox; for example, while the two Jennifers simply passed out when meeting each other, the producers explain that had "young" Jennifer fallen, hit her head and sustained a fatal injury she would not have had a future self to trigger the incident, resulting in a paradox.
    • Likewise, in the 2011 video game, the beginning of Episode 2 requires Marty to retrace his steps and keep his grandfather from getting killed while trying not to run into himself from a few hours ago (during the events of Episode 1). To make things even more confusing, the end of the final episode of the game has Marty arguing with Marty and Marty over which timeline is correct, while a confused Marty looks on. And yet Doc still says, while all of these Martys are having their little discussion, that them meeting each other could destroy the space-time continuum. Still seems fine at the moment.
    • In LJN's Back to the Future Part II & III game for the NES, though, as you leave behind temporal clones of yourself every time you leave and then revisit one of the three time periods (1955, 1985, and 2015) in the Part II section, collision with your temporal copies causes you to lose a life.
    • The ride at Universal Studios ends with a frantic order from Doc to leave the DeLorean before you encounter your past self coming in.
  • In Happy Accidents, Sam explains that it is impossible for time travelers to travel back within their own lifetimes; the only time travel possible is movement far into the past.
  • In the film Southland Tales, a huge part of the plot hinges on this twist, revealed late in the film:
    • Two time-travel-created copies of the same person shake hands with each other, setting off the end of the universe.
    • Boxer Santaros avoids this as someone has already taken the care to murder his double. Or perhaps the original.
  • Subverted in Primer: when the protagonists start time traveling, they take elaborate precautions to avoid meeting themselves, but it becomes progressively more clear that (aside from creating permanent duplicates of themselves) these precautions are totally unnecessary. By the end of the movie, Aaron has drugged his past self's breakfast and stowed him in the attic, and is then promptly attacked by yet another, future, version of himself.
  • Star Trek (2009): Spock Prime insists that Kirk cannot tell the younger Spock about his existence, with the heavy implication that some kind of universe-ending unpleasantness would ensue if he did. Subverted at the end, when Spock Prime then seeks out and introduces himself to himself, and all-but-admits that he misled Kirk so that he and young Spock would develop the same friendship that existed between Spock Prime and the Kirk of his reality.
  • Super Capers seems to be fine with the two meeting each other, but if they physically touch each other... that's a different story.
  • Déjà Vu (2006) took care to avoid potential paradoxes like this in an unwritten way by ensuring that the Denzel who traveled back in time died without ever meeting his younger self.
  • Godzilla vs. King Ghidorah involves a Time Travel plot to remove the original dinosaur that became Godzilla from an island occupied by Japanese Troops in WWII. When one character asks why they couldn't bring one of the Japanese WWII veterans they knew with them, since they'd know where the dinosaur would be, the Futurians who had the time machine explain that if the same person was in the same point in time twice, it would cause a paradox that would cause one or both of the person in question to be wiped from existence.
  • Played straight to gruesome effect in Timecop. Physical contact with your other self leads to... well, it's not pleasant. As mentioned in the comic book entry, this is specifically due to the same matter occupying the same space; as long as they didn't touch, meeting was fine.
  • Timecop 2: The Berlin Decision: Meeting up with your past self in this movie does not cause the person in question to melt out of existence, but results in them fusing into straight-up Body Horror.
  • In Project Almanac, Quinn draws a smiley face on his own neck in the past to test the ripple effect, waking himself up and causing both of them to start shifting in and out of existence. Lucky for him, they manage to drag him away before it becomes permanent. Jessie has this happen to her completely near the end of the film, forcing David to go back to the beginning in an attempt to correct for all of it.
  • Openly defied in Bill & Ted's Excellent Adventure, where Bill and Ted encounter and interact with their future selves near the beginning of film and is actually a plot point in advance.
  • Referenced in Avengers: Endgame, but averted. When Scott Lang suggests building a time machine, the others becomes exasperated when it becomes clear that Scott is getting all his ideas about how time travel works from movies, including never meeting their past selves. The smarter heads explain that time travel works on multiverse theory, meaning that nothing bad happens when Captain America and Nebula encounter their past selves save for it leading to them fighting. That said, they still have to avoid causing any massive changes, not for their own timeline's sake but in order to keep from screwing up the other timelines they visit.
  • In the sci-fi short Hyperlight, an FTL accident causes two versions of the same spaceship to collide. The female pilot retrieves her co-pilot (and lover) who registers as alive but has no vital signs, and boards the second spaceship to find the co-pilot alive and herself dead. Realising that the two of them can't exist simultaneously, she has him Thrown Out the Airlock so 'her' boyfriend will revive.
  • Tenet: An "inverted" person moving backwards through time who touches their past self will cause both their particles to self-annihilate, so it's recommended for those who invert to wear fully enclosed clothing covering every inch of skin. This causes the heroes at times to not recognize their future selves or allies.

  • This may happen to you in "Dimension of Doom", one of the Star Challenge books. You can end in a planet crammed with dinosaurs and a Cyborg half-human and half-robot asking about him, he replies he's you in a future after being combined with your robotic companion. Accept your destiny and he'll disappear. Attempt to change your fate and you'll become that Cyborg (bad ending)

  • In Larry Maddock's Agent From T.E.R.R.A. series about time traveling cops trying to defeat a rogue time traveling agent turned conqueror, this is explicit. Why is never explained, but at least once per book the plot hinges on one or more people being prohibited from entering a certain period of time (minutes to hours) because they were then (sic) already. One very nice feature of this series is that several times the main character will race toward his time machine, immediately phase out of the time stream, and then relax: going to bed, taking care of wounds, preparing and eating a hearty meal, etc. He reflects that he could spend literally years preparing to go back to the precise micro-second he left, so now there is no hurry at all.
  • In All Our Yesterdays, it's claimed that if past selves see their future selves, both will be erased from existence, but it's a lie intended to stall them.
  • Addressed in book six of the Artemis Fowl series, appropriately titled The Time Paradox. Meeting one's past self is warned against, but for pure caution's sake — never before have the selves met, so nobody can say for sure it wouldn't destroy the universe. Ends up subverted — Artemis meets himself, does battle with himself several times (and Butler, who's arguably the more dangerous of the two), and eventually the two Artemises collaborate to bring down Opal Koboi. The timeline seems harmed not at all, and there's evidence that it actually resulted in a Stable Time Loop leading to the events of the first book.
  • In The Book of the New Sun, Severian feels absolutely certain that if he accidentally met himself while time traveling, one or both of them would go mad and kill the other.
    • In the sequel The Urth of the New Sun, Severian dies but some equally real duplicates of him are created. When one of them meets Severian through time travel, the duplicate explodes.
  • In Anne McCaffrey's Dragonriders of Pern novels, time-travel is generally exhausting, but is substantially more so when traveling near oneself. This one's also an example in a Stable Time Loop world.
    • Note that both selves will feel the effects. If you suddenly feel dizzy and weak for no reason, it might mean that future-you is in the vicinity.
    • In Moreta: Dragonlady of Pern, to stop a plague, Moreta and her dragon repeatedly loop back over the same time period. Though her appearances are in many different locations, the repeated trips prove lethal.
    • The most recent books imply that this problem is exclusive to dragonriders, and is the result of their telepathic bond with their dragon inadvertently becoming duplicated as a result of the time travel.
    • This reaction is the reason Lessa survived Fax's attack on Ruatha Hold. When adult Lessa unwittingly traveled to the morning of the attack, child Lessa was awoken by the feeling of unease brought about by her adult self's presence and instinctively hid in the watch-wher's kennel.
  • In The End of Eternity, there are time periods in regular time allocated for an Eternal to use, and naturally, you are not to use them twice. However, when the protagonist goes into regular time illegally, he doesn't keep track as well, so he almost meets himself (that is, he catches a glimpse of his past self). There don't seem to be any consequences, but he is extremely and irrationally terrified.
  • In Fortunately, the Milk, the time-traveling protagonist is repeatedly warned of the potentially disastrous consequences if the same object from two different points in time touches itself; nobody's entirely sure what the consequences would be, exactly, but the leading theory is that it would cause the destruction of the entire universe. Inevitably, the climax of the story features an encounter between two versions of the same object, with dramatic — and entirely unexpected — consequences.
  • One of the most important rules of Time Travel in Harry Potter? Don't be seen by yourself. You could panic and kill your past or future self. Notable for not really being a result of time travel so much as just being a duplicate. Though not spelled out explicitly in the books, this could have something to do with the existence of Polyjuice Potion — in most non-time-travel related situations where you notice a duplicate of yourself, it means someone's up to no good. As Harry's own experience with Time Travel, which was the only one the readers were able to follow, turned out to be a Stable Time Loop, the killing-your-past-self thing is unlikely to ever happen.
  • Subverted in The Hitchhiker's Guide to the Galaxy novel Life, the Universe and Everything; Ford Prefect and Arthur Dent arrive on Earth shortly before its destruction. Ford (who had, in the previous novel, explained to Arthur that history cannot be changed because it all fits together like a jigsaw), warns Arthur against phoning to warn himself. Not because it'll do anything to the timestream, but just because it won't work. It had already been noted in The Restaurant at the End of the Universe that no matter how many times you visit the restaurant in the title, which you would always do in the universe's last half-hour or so, you are guaranteed to never run into yourself "because of the embarrassment this usually causes," despite this being impossible. How the people responsible for the restaurant's operation pull this off is not explained, but it is lampshaded magnificently along with other things about Milliways by the Guide's repeated use of the phrase "This is, of course, impossible", and the restaurant's advertising slogan: "If you've done six impossible things today already, why not round it off with breakfast at Milliways, the Restaurant at the End of the Universe?"
  • In Johnny and the Bomb by Terry Pratchett, the time-trolley sends Johnny forward in time just before his past self sees him, apparently to avoid paradox. It's still enough to shake the time travelling Johnny: "I saw the back of my own head! No-one's done that since the Spanish Inquisition!"
  • Diana Wynne Jones' novels often involve alternate universes and occasionally also time travel, which means they touch on this from time to time:
    • A Sudden Wild Magic has an example similar to the Stargate one below — travel into alternate universes is possible, but causes instant death for anyone with a counterpart in that universe.
    • In Charmed Life, the character who manages to travel into an alternate universe does so via a method which cyclically displaces all her alternate selves, so every universe that had a version of her continues to do so. In fact, the main qualification for Chrestomanci, the enchanter who keeps all the other magic users in line, is that he have nine lives. This makes it possible for him to go to other universes comparatively easily: he has the extra lives because the alternate selves who would otherwise have them don't exist.
    • But in A Tale of Time City, Vivian, Jonathan and Sam manage to be on the same railway platform in three different incarnations at the same moment and nothing happens - although they're careful not to be seen, it's just in case they change history. More than they already have, anyway.
  • Hinted to normally be the case for the Eternal Champion in Michael Moorcock's related stories. Different incarnations do meet each other and even team up from time to time under suitably unusual circumstances, but once the emergency allowing for the encounter passes they inevitably have to part ways again shortly thereafter (sometimes downright abruptly) to avoid putting too much unspecified strain on the multiverse.
  • The Rifter: Averted. When Kahlil arrives in a Basawar where history was changed, the version of himself in the new time is already dead. He does have two sets of memories coexisting confusingly in his head, though. Eventually, he finds the bones of his other self and they merge into his body; at the same time, he feels like his two histories have become truly integrated into one personality.
  • In one of the R Is For Rocket stories, a man participating in a time-travel safari has this explained to him. The 'bump' they felt just before arrival was the time machine leaving at the end of the safari, the tour guide explains that "Nature doesn't allow that kind of thing- man meeting himself".
  • In Sonic the Hedgehog in the Fourth Dimension, older and younger selves could co-exist, but not touch: if they did, they melted together somewhat painfully to become one self. Sonic did this ("Now I'm twice as cool"). He also did this with the evil anti-Sonic, Cinos, causing some alarm as to whether good or evil would win out in the resulting Sonic. Good won. Imaginary creatures threatening to rewrite history kept people from asking too many questions. Still, at the end, it was two positive Sonics plus one negative Cinos, which should equal one positive Sonic.
  • Star Wars Legends: The Last Command by Timothy Zahn has a variant of this trope, involving clones instead of time travel. Clones grown near others set up "resonance effects" in the Force, which can drive them insane, and when Luke encounters his clone, he finds the experience incredibly off-putting: there's a buzzing hum in the Force that makes it hard to concentrate or think, making it difficult to fight the clone. This only seems to affect clones whose growth has been accelerated to an extreme degree — having them grow up in under a year, for instance — and Force-sensitive clones, since the clone army in the prequels (who take about 10 years to grow up) doesn't have any problems with this. Thrawn figures out a way around it in the same novel, using lizards that can push away the Force to protect against the clone madness and dramatically decrease the time to grow them even further.
  • The Time Scout series, which already presents time travel as potentially dangerous if you don't get the small details right, also avoids the meet-yourself problem by making it clear that you must never go back to a time when you already exist, either by having been born by then, or having previously visited via time travel; otherwise, since you can't be in two places at once, the "current" you who went back in time would simply wink out of existence the instant you arrived, and that's the end of you.
  • In the Warcraft time-traveling trilogy The War of the Ancients, the character Krasus (a dragon shapeshifted into an elf) is unable to transform into his dragon form because he already exists, as his younger counterpart Korialstraz. Likewise, Korialstraz is unable to transform into anything else. The two are weaker the farther apart they are, but become stronger when they're close. The two work around this problem somewhat by giving each other one of their scales.
  • In Connie Willis' time-travel books, you simply can't go back to a time you've already visited. If you try it—or if your presence, for any reason, would cause a paradox of some sort—either the "net" (via which one time-travels) simply won't open, or it will deposit you slightly awry (in time and/or space) of your intended destination. Cosmic Censorship may be at work here: if you cause a paradox, then the next version of you is sent to a slightly different point (or the machine fails), repeat until there's no paradox.
  • A non-time-travel variant in the 13th Reality books. If you meet your Alternate Self from another reality, one of you will spontaneously cease to exist (which one is apparently completely random). In the second book, the Big Bad takes care to kidnap and lock away his Alternate Self from the protagonist's universe before implementing his plans, just to prevent the chance of the two of them meeting.
  • Sword Art Online: The reason RATH pursues Project Alicization (an attempt to create a human-equivalent mind entirely from scratch) is because artificial Fluctlights (minds/souls) are inherently more fragile than the natural variety, and can literally break down when confronted with a mind too similar to themselves. This is addressed a few times over the course of the Alicization arc:
    • RATH's lead developer Higa introduces this concept by demonstrating a copy he made of his own mind. When confronted with the original Higa, it has a Freak Out and accuses him of being an imposter, its voice becoming increasingly angry, irrational and filled with static until eventually it cuts out.
    • In the Back Story of the Underworld simulation, Administrator attempted to extend her life by overwriting her Fluctlight onto that of a young girl. However, as soon as the copy was complete, both Fluctlights instinctively rejected the other, causing them to fall unconscious and begin self-destructing in random places until they were no longer similar. This resulted in the younger girl taking up the directives of the Cardinal System (the Underworld's automatic Game Master, which Administrator had previously subverted and absorbed) to become Cardinal, Administrator's Good Counterpart.
    • Played for Horror with the Star King, a version of Kirito who retains over a century of additional memories from his time trapped in the Underworld. A backup of his mind has zero difficulty coexisting with the teenage Kirito, because his human memories make up only a small part of his life and he no longer considers himself the same person.
  • In the first Apprentice Adept trilogy, only those who do no have an other self are capable of perceiving or crossing through The Curtain (an energy field denoting the barrier between the worlds of science-based Proton and magical Phaze). So meeting your other self was literally impossible. Stile and his Phaze self, the Blue Adept are able to interact, but that was a temporary Sharing a Body situation.

    Live-Action TV 
  • In 7 Days (1998), whenever Parker travels back in time, his younger self, the sphere, and one trip's worth of their alien fuel source vanishes.
  • 12 Monkeys: Invoked by Cole in the pilot, and played with when he brings both the 2015 and 2043 versions of Cassandra's wristwatch together. The result is a 'paradox', depicted here as a slowing down of time in the immediate vicinity that affects everyone present except Cole.
    • This becomes a plot point in Season 2, as the Messengers — the Twelve Monkeys' Super Soldiers — hijack the Project Splinter time machine and use it to go back in time to kill the Primaries (humans who act as Cosmic Keystones maintaining time) with weapons made from their own bones, creating Reality Breaking Paradoxes to try and collapse time.
  • This trope gets smashed into the ground with the character of Martin Summers in Ashes to Ashes (2008). Then again, in the light of the finale, whether it actually applies is debatable.
  • In Crime Traveller this is one of the rules of time travel. It was never entirely clear what would happen if someone met their past self, but the implication was that it wouldn't be good. Strangely, one of the other rules was that the time travellers needed to be back in the room with the time machine at the moment they left. In theory, this means that they should see themselves leaving and break the first rule but that was never shown to happen.
  • Batwoman (2019). Just the presence of an Alternate Self in the same universe (caused by the collapse of The Multiverse in Crisis) is enough for both versions to start dying before they've even met each other. In this case it's an alternate Beth Kane who never became the mad supervillain Alice, so Kate Kane is presented with a Sadistic Choice over whether she should try to save her evil sister at the expense of this kind and decent version of her.
  • Doctor Who: This has, unsurprisingly, come up several times, though the Doctor's had no trouble (usually) meeting past versions of himself.
    • "Inferno": The Doctor, while visiting a fascist Mirror Universe of Earth, claims that if that universe's evil version of the Brigadier were to meet the original it would destroy both universes. The evil Brigadier wants to force the Doctor to save him from his Earth, which volcanic eruptions would destroy in a matter of minutes.
    • The original series has several stories where multiple incarnations of the Doctor were brought together in the same place at the same time, without any apparent ill effects to the Timey-Wimey Ball that is the Whoniverse. (Most of the time, this could be explained by the fact that the multiple incarnations aren't entirely the same person.)
    • "Mawdryn Undead" shows that when the Brigadier met his younger self, the resulting "Blinovitch Limitation Effect" had the effect of giving the younger Brigadier a nervous breakdown, as well as enough Pure Energy to kill a half-dozen previously immortal aliens. In terms of the Brigadier, this created a neat Stable Time Loop.
    • In "Father's Day", travelling to the same place twice allows Rose to create a Temporal Paradox by watching herself save her father from getting killed in car accident while she was still a baby. Later in the same episode, she gives more power to that story's Clock Roaches by touching her own infant self. It's revealed that cleaning up paradoxes without such things happening is part of what the Time Lords did, but now that (for the most part) there aren't any Time Lords any more, there's no one to prevent such things from happening. This may explain why no flying killer time monkeys appeared during any serial with a title of the form "The [number] Doctors".
    • The 2007 special "Time Crash" blamed Peter Davison's Doctor ageing 30 years on temporal weirdness resulting from being in the same room with himself. (This same explanation may be used to justify the relatively minor differences in appearance occurring in multi-Doctor stories in the original series- the biggest of which (besides The Other Darrin example of the new First Doctor) was the obviously-older Second Doctor in "The Two Doctors". But then the Doctor Who Expanded Universe explains the latter, anyway.)
    • "The Hungry Earth": At the beginning, Amy and Rory see their future selves waving to them from a distant hilltop. Amy wants to go over and meet herself, but the Doctor tells her it's a bad idea, and it doesn't happen.
    • In "The Big Bang", Amy meets her seven-year-old self ("Amelia"), and touches her a couple of times in sizing her up. Possible Fan Wanks include a) Amelia is from an alternate timeline, so they're not technically the same person (apart from anything else, she vanishes minutes later, so she obviously doesn't grow up to become Amy), and b) with the whole Universe toast, save for the Earth and the TARDIS explosion acting as a substitute Sun, there are probably no Clock Roaches, and really more pressing matters at hand than a couple of silly old paradoxes. It's also lampshaded later when Amy mentions that she met herself, and Rory responds "To be fair, the universe did blow up."
      • In the same episode, the "limitation effect" was a small spark between two of the same sonic screwdriver.
    • "Space"/"Time" is a Comic Relief special where Amy meets herself from a few minutes down the line. The only danger is to Rory (risk of hormone-based overload from watching Amy flirt with herself).
    • In "The Girl Who Waited", two Amys (Amies?) meet and the problem is being able to save only one. The TARDIS can't handle the paradox of two Amys in one time and place.
    • "The Day of the Doctor" starts with three incarnations of the Doctor meeting up thanks to the Moment opening rips in space-time. The Tenth and Eleventh Doctors meet the War Doctor, a previously-unmentioned incarnation that existed between the Eighth and Ninth Doctors who renounced his name during the Time War. In the end, all thirteen incarnations meet at a single point in time to put Gallifrey into another dimension, including the as-yet-nonexistent Twelfth Doctor. However, it's specifically mentioned that only the Eleventh Doctor and the Twelfth will remember this happening, as the events are asynchronous with the timelines of the earlier Doctors.
    • In "Listen", the Doctor tries to get Clara to travel to her childhood, but Clara (who is at the time psychically linked with the TARDIS) gets distracted and travels to her Love Interest's childhood. The Doctor doesn't yet know that and tells Clara to stay in the TARDIS in order to avoid meeting her past self. Later, Clara finds out she accidentally traveled to the Doctor's own childhood (as the First Doctor) and created a Stable Time Loop. She demands that the Doctor leave this time and not try to find out where and when they ended up.
    • "Fugitive of the Judoon": Gat is outraged when she realizes that Ruth and Thirteen are both incarnations of the Doctor, fearing the damage having two of the same Time Lord so close to each other could do to the timeline. Later, when Ruth drops Thirteen back in Gloucester, she cites the same reason for not letting her TARDIS get too close to Thirteen's. "Once, Upon Time" establishes that Gat and Ruth are from Gallifrey's past, suggesting their era hasn't got safe multi-incarnation meetings sorted out yet.
  • The Flash (1990): In "Flash Forward", the Flash is bumped ten years into the future by trying to outrun a heat-seeking missile launched at him by Nicholas Pike, to arrive in a world where Central City has been taken over by Pike. When that Flash is sent back in time, he encounters his past self at the point just before the missile launches and reprograms it to halt its launch, then merges with his past self to deal with Pike and send him behind bars again.
  • The Flash (2014): Averted in "Fast Enough". At the scene of his mom's murder, three versions of Barry Allen were actually present — his present self, his future self, and his child self. While Kid!Barry was whisked away too quickly to recognize either of them as himself, Present!Barry and Future!Barry make eye contact and recognize each other. Somehow, this doesn't break reality. Also happens later, when Barry deliberately travels back in time to get help with the speed equation from Eobard Thawne. At the end of the episode, Past!Flash ends up helping Present!Flash get back home. The season 2 finale ends with Barry traveling back to his mother's murder again, but this time, he stops it, causing the Barry from the season 1 finale to dissolve into thin air. In Season 3, Barry travels to the future in order to discover Savitar's identity and meets his gloomy future self. Then there's The Reveal that Savitar has been Barry's future time remnant all this time.
  • Generally averted in Heroes, as several characters have met past or future selves without anything happening because of it. It's occasionally discussed, though:
    • The Genre Savvy Time Traveler Hiro Nakamura runs into his future self, only to cry in dismay, "Aren't you afraid of disrupting the Space-Time Continuum?"
    • And before that, when he realizes he's accidentally ended up talking to his past self on the phone, he hangs up instantly, exclaiming "Great Scott!"
    • Season four had Samuel explain to Hiro the dangers of the butterfly effect when Hiro goes to change an event with major influences on events surrounding his past self.
  • NBC's Journeyman doesn't even bother to explain why you shouldn't be seen by your other self — it just assumes you already know that. Though the main character is able to have a fistfight with his past self, so it's at least OK as long as your past self doesn't get a good look at you.
    • Like Back to the Future, this winds up less of a cosmic rule and more of a guideline to prevent paradoxes, since the timeline is very malleable (case in point, the time he left a digital camera in the 1980s, which subsequently retconned his own son out of existance). But the protagonist is very Genre Savvy from the get-go.
  • Averted in Kamen Rider Den-O. The character Yuuto Sakurai went back in time and recruited his young adult self personally, bringing him to 2007 to become Kamen Rider Zeronos; the younger Yuuto also has his older self's contract with the Imagin Deneb, because said contracts are apparently retroactive.
    • The Movie I'm Born!! zig-zags this trope. The Hero Ryotaro goes back in time and meets himself as a child, the shock of which causes both to faint. Unfortunately, the adult Ryotaro suffers Easy Amnesia, forgetting his contracts with his ally Imagin, meaning he can't become Den-O; however, the retroactive rule means that the the younger Ryotaro can, and at one point transforms into a miniature Den-O. This causes bigger problems later in the series, where the "forgotten" contracts cause the Imagin to seemingly disappear.
      • On the other hand, the film's climax has Yuuto revealing that he "borrowed" Ryotaro from three other points in the timeline (using a powerful sedative to knock them out), which allows all four Den-O Imagin to exist at the same time and help fight the Big Bad Gaoh and his minions.
  • Kamen Rider Fourze gleefully takes a hammer to this trope in the Crossover film Movie Wars Ultimatum. When Gentaro Kisaragi from five years in the future comes back in time to our present, the very first thing he does is pull his past self aside (via tackle), say "Hi, me!", and ask to borrow his Transformation Trinket since he destroyed the future version as a Secret Test of Character for one of his students. Present-Gentaro's first reaction is of course utter shock, but after a moment he gladly loans the belt.
  • Kamen Rider Zi-O: Absolutely averted. Ordinary High-School Student Sougo Tokiwa spends the first part of the series in utter denial that he could possibly become an Evil Overlord fifty years into the future, until he takes an unplanned trip to 2068 and meets Ohma Zi-O face-to-face, confirming that it really is him. He doesn't take it well, especially because Ohma Zi-O remains convinced that he's fulfilled his childhood dream of becoming a wise and just king by ruling over the planet with an iron fist. Sougo and his future self meet (and fight) several more times over the course of the series, but they actually work together in the final arc to help defeat the actual Big Bad Swartz, and when Sougo takes a third option to give everyone a happy ending, his future self says "It was interesting meeting you, my younger self" before he fades from existence.
    • The Movie's Big Bad is another future version of Sougo,note  separate and distinct from Ohma Zi-O, who used the original as a decoy for his plan to reset the Heisei era because he believes it to be "ugly". Ohma Zi-O actually intercedes to loan Sougo a portion of his power (giving him a movie-exclusive powerup) so he can defeat their common enemy.
    • The series handles this much more humorously in the Kamen Rider Gaim arc. Though Sougo manages to defeat Another Gaim by himself, Kouta Kazuraba uses his god-like powers to send Sougo three days into the past so he can learn An Aesop about relying on his friends. While Sougo's allies are pretty annoyed about this flagrant screwing with the timestream (including Woz), the two different Sougos get along just fine.
  • Legends of Tomorrow initially averts this, as Professor Stein meets his younger self and there are no repercussions, possibly because his younger self didn't realize who he was talking to. They meet again in another episode, and while they permanently change the timeline by causing Stein to have a daughter there are still no problems.
    • Played straight however in the Season 2 Finale, however. In this case the Legends, out of options, break the fundamental rule of time travel and double back on their own timeline. Despite initially trying to avoid interacting with their past selves, they eventually do. The two versions of Rip upon seeing each other have just enough time to say (in unison) "Oh bollocks!" before there's a Time Crash.
    • The rule here is that while you can meet a version of yourself in your own natural timeline, like Stein's younger self, you can't meet through time travel a version of yourself that is ALSO time traveling to that same spot because that can cause timequakes. This basically makes sure the Legends can't get infinite do overs by just traveling back 5 minutes to try again, because they'd see their other selves. Though they get around this in the first season finale by having Sara and Firestorm travel to the point in the first episode where the whole team first took on Savage, by making sure they remain far in the distance where the Legends can't see them. Notably they had to hide at one point so the other Firestorm didn't see them when he was flying by.
  • Averted in Loki (2021). Two versions of Loki (one of them being female) meet and interact with each other just fine. Them falling in love with each other is another matter. Episode 5 introduces even more Lokis and since most of them haven't gotten the Character Development to move beyond the Chronic Backstabbing Disorder part of their personality, they end up betraying each other and fight over what little territory and supplies exist where they are all trapped.
  • In the outtake "Orchid Orientation Film" from the Lost season 3 DVDs, a time travel experiment involving bunnies apparently goes wrong. The scientist shields one of two identical bunnies from the other and shouts, "Don't let them near each other!" The series proper averts the trope, though.
  • Misfits: Having discovered the identity of Superhoodie to be future!Simon, Alisha is warned not to tell anyone else. Since everybody is still curious as to his identity, she awkwardly tries to convince them to leave him alone.
  • In the many time-traveling episodes of Odd Squad, a rule is stated that if your other self sees you, it will cause a "Timetastrophe," which causes time to fold in on itself. The Timetastophe has three phases: First, there are the timequakes. Then, the opening of time holes let in a 1920s businessman, a viking, and a gogo dancer. Lastly, the worst of all, the time sheep appear.
  • Red Dwarf does this too, at the end of series 6. The crew's future selves travel back in time to meet them as they are at that point for some repairs. Kryten admonishes the crew to not contact the future Dwarfers to avoid gaining inappropriate knowledge of the future. They watch instead, and despise what they became. The result? 'I say we fight. ... Better dead than smeg.' From the snivelling, whining coward (according to everyone, including himself) Rimmer. Causes a paradox anyway, but that's what they wanted at that point.
  • In Sanctuary, after Helen travels back in time to stop Adam from destroying Praxis, she is stuck there and has to take The Slow Path, while remaining in hiding from anyone who might know her, including her other self. It's not stated that physical contact would be disastrous, but Helen doesn't recall meeting another Helen, so she can't risk being seen.
  • In the Korean drama Sisyphus: The Myth, an object or person from the future coming into contact with their past self causes what's referred to by the characters as a 'time paradox'. The effects vary - prolonged contact can cause the future object/person to phase out of existence. In the case of people, the past self touching their future self (even if its their future selves' skeleton) can cause them to gain memories of their future.
  • Played with in the So Weird episode "Pen Pal". Annie is able to meet herself from a parallel universe without consequence, but only one of them is supposed to exist in that dimension, so they're unstable. When they touch each other, Parallel Annie is destroyed.
  • Someday or One Day: Xie Zhi Qi, in his brother Xie Zhong Ru's body, talks to his younger self and encourages his unstable tendencies. In adulthood, Zhi Qi goes back in time to his brother's body, where he murders people and encourages his younger self, and so on...
  • A non-time-travel variant occurs in Stargate SG-1: anyone who travels to another dimension is subject to quantum seizures if they have a living counterpart. You can survive for short periods, and are exempt if your counterpart is dead, which saves Daniel in one episode, Kowalsky in a second, and Carter in a third. Time travel, on the other hand, doesn't seem to have this effect in any way.
  • The Star Trek episode "The Alternative Factor" involves two identical men named Lazarus. One is from our universe and insane. The other is from an anti-matter universe. Apparently, if both meet in the same universe, it destroys both of them. No explanation was given why the anti-matter Lazarus didn't blow up upon contact with any matter from our universe.
  • One Timecop episode has a retired cop from the future use the time machine to try to recover the loot from a criminal he once caught. He ends up taking his past wife hostage, causing his past self to start to approach him. The future cop warns him of the consequences (see the Film section), but the past self is willing to let both of them be disintegrated to protect his wife. This doesn't happen, though.
  • In Timeless, it's stated that time traveling to a period when you already exist can be extremely hazardous to your health. Apparently, it wasn't pretty for the test pilot, who attempted that. This counts both for one's own lifespan (i.e. can't go to a time after you're born) and one's trips into the past (can't revisit the same time). In Season 2, Flynn reveals that Lucy from 2023 visited him 2 weeks after his family's murder to give him her diary, violating this rule. Also violated in the season finale, where a second Lifeboat arrives from the future, with Future!Wyatt and Future!Lucy meeting their present selves and telling them their plan to save Rufus.
    • In the show's Grand Finale, which picks up where the original season 2 finale left off, future!Lucy and future!Wyatt do indeed experience side affects in the form of seizures, before returning to their own time in the old lifeboat, leaving their future!lifeboat (an upgraded version) with their past selves.
    • Also in the series finale, Flynn goes back to 2012, to kill Jessica, so that she never kidnaps Jiya, which means Rufus never dies and they can take out Rittenhouse. He experiences the seizure side effects, but manages to send the lifeboat (upgraded with autopilot) back to the Time Team, before going to watch his past self and his family from outside the window while slowly dying.
    • Finally, in the finale, they flash forward to 2023 show Lucy, Wyatt, and Rufus going back to 2014, 2 weeks after the murder of Flynn's family, so that Lucy can give Flynn the journal, allowing the completion of the time loop, thus bringing the series full circle. This scene shows the Time Team experiencing the side effects of traveling into your own timeline.
  • On another Whoniverse series, Torchwood:
    • The never-aging Captain Jack, while trapped in 1901, orders himself cryogenically frozen to avoid meeting in the intervening decades before the present, and to prevent himself from meeting his "The Empty Child" self in 1941 and "Boom Town" self in 2006, as well as the version of him that has lived through all this already.
    • At the end of "Kiss Kiss Bang Bang", the whole team, having gone back to earlier that day, are told that they must avoid themselves.
    • It seems, though, that they're more worried about changing their own history than a Time Crash resulting from simply being in the same place, since the same person being in the same place has happened so many times safely. If you interfere where you've already interfered, though, the Clock Roaches will getcha, as seen in the aforementioned DW episode, "Father's Day".
  • The Twilight Zone (1985): Discussed in "Shatterday". When Peter Jay Novins threatens to go to his apartment and fight his alter ego, the alter ego speculates that this would be a very bad idea as each of them could be destroyed in the process. He cites the theory that only one of each thing can exist in the same place at the same time. This proves not to be the case when the two of them come face to face in the final scene. It is implied that the alter ego knew this already.
  • The Umbrella Academy: Downplayed. The Commission explicitly advises against two versions of a person existing in close proximity within the same timeline. While the universe doesn't collapse, both versions would go through "The Seven Stages of Paradox Psychosis," which start at denial before devolving into homicidal rage. In an act of desperation, Five meets his "older" (technically younger) self order to steal the latter's briefcase so the rest of the Academy can return to 2019. Hilarity Ensues when they both descend into madness and attempt to kill each other (thankfully they don't, as it would cause a Grandfather Paradox).

  • In Big Finish Doctor Who story Time of the Daleks the Eighth Doctor claims if two versions of someone meet the older version will be destroyed, as the younger version needs to become the older version. It is revealed this is the reason General Learman destroyed the Dalek Pilot. It was because of the lack of a pilot that the Daleks turned her into one and they are trapped in a Stable Time Loop.

    Tabletop Games 
  • In the core Timemaster rules (from the defunct Pacesetter Games), it was impossible to meet up with yourself. Any attempt to travel to a time period you already occupied put you into a "Loop Trap" — you'd basically be "stuck" reliving the time covered by the loop over and over. Of course, you wouldn't realize this, because it would be the first time through every time. Better hope one of your teammates is willing to pull you out of the loop. Timetricks, a Timemaster supplement meant for more experienced groups, included a little gadget that would let you bypass a Loop Trap for a short period of time, assuming it worked.
  • Played with in Genius: The Transgression. Interacting with your younger self is relatively safe compared to all the other stupid things you can do during a time-travel jaunt. However, going back in time to the same moment twice and coming into contact with your own time-traveling self is an excellent way to drive yourself all sorts of crazy — when the game describes an act as "about the stupidest thing you can do without a death ray and a bottle of tequila," you know it's a bad idea. It also handily prevents an "army of temporal duplicates" scenario from coming to pass.
  • In the obscure Dungeons & Dragons second edition Splatbook Chronomancer, this is in effect for anyone who travels to a time period even close to when they already exist (either from their natural life or other time travel jaunts). Various forms of Clock Roaches will attempt to force a time traveler into a temporal frame they didn't previously exist in, some rather destructive. Eventually, should they avoid all those, a Timey-Wimey Ball will automatically force the offending time traveler to a point forward where it's no longer an issue.
    • Merorem from The Gates of Hell can travel in time. If he tries coming too close to his alternate self, he is pushed back and stunned.
  • Continuum not only inverts this, but expects this will happen and has rules (both etiquette and mechanical) on how to handle such an event (dubbed a "Gemini incident"). Remember to respect your elders.
  • Magic: The Gathering has rules in place to partially enforce the alternate-universes version of this, although whether the time-travel version is also enforced depends on whether you're a legendary creature or a planeswalker:
    • The "legend rule" applies to legendary creatures (or legendary permanents of any type). Legendary permanents represent unique, named characters, places, or objects rather than generic ones; originally, the legend rule stated that if a legendary permanent entering the battlefield shares a name with one already on the battlefield, both are sent to the graveyard. However, two legendary permanent cards could represent the same character without sharing a name. For example, Kamahl, Pit Fighter and Kamahl, Fist of Krosa represent the same character but have different names, so they could coexist on the battlefield. The rule was later amended to be a softer version of this, with multiple copies of a legendary permanent being allowed to exist as long as they are on different sides of the battlefield; If one player ends up with two or more copies of the same legendary card in play, they must sacrifice all but one as soon as they enter the battlefield.
    • The planeswalker card type had a similar rule to the legend rule, only it refers to a planeswalker's subtype; if a planeswalker entering the battlefield shares a subtype with one already on the battlefield, both are sent to the graveyard. This is because there are no generic planeswalker cards; each represents a specific character, and the subtype indicates which character is represented. This means that two planeswalker cards that represent the same character without being the same card still destroy each other. For example, a popular strategy to combat one-time Game-Breaker Jace, the Mind Sculptor was to either remove him by casting his less-expensive version Jace Beleren, or use the fact that Jace Beleren is less expensive to put him into play before a Mind Sculptor is cast at all, meaning the other player would have to waste a Mind Sculptor card in order to clear the way for another one. Since both represent the same character (in game terms, since both are Planeswalker - Jace), they destroy each other by being in play at the same time. Like above, this rule was changed, being removed completely and instead making all Planeswalkers have the legendary type, and it's associated restrictions, as a rule.
  • Sentinels of the Multiverse, especially in the online version where this is strictly enforced. Each variant card has the same deck and since there's only one deck for each hero, you can never play more than one variant of the same hero.
    • The big exception to this is villains and heroes who are alternate versions of the same person. (The Dreamer and the Visionary, Legacy and Iron Legacy, all the hero decks in the OblivAeon expansion, etc.) In the digital version of the game, characters that are alternate versions of each other have special intro dialogue before the game begins, something that's usually only the case when characters are Nemeses.
    • Omnitron offers another aversion. You can play a game against Omnitron (the villain deck) using Omnitron-X (the hero deck) inside Omnitron-IV (the environment deck). This is because, despite the shared name, they aren't the same entity. Rather, Omnitron is the creator of Omnitron-IV and (in the future) Omnitron-X. In fact, Omnitron and Omnitron-X are Nemeses, X having come back in time to shut down its predescessor before it can trigger a Bad Future.
    • One of the last mini-expansions is for the Void Guard, 4 powerful heroes that draw their powers from a similar source. Why are they all packed together? Because Void Guard are the same characters as The Southwest Sentinels, who were already in the game as a quirky deck with 4 character cards for one player. There's now nothing to stop one player from playing as The Sentinels, while the rest play as the individual members of Void Guard, resulting in each character being on the table twice.
  • Warhammer 40,000:
    • One ship responding to a distress signal arrived before it had left due to the way the Warp works. Just before they were destroyed by the threat they were responding to, however, they managed to send out a distress signal...
    • Waaaagh! Grizgutz entered the Warp and exited earlier than they left. Just as they were about to leave in fact. The older Grizgutz attacked and killed his past self so as to have two of his favorite gun, and "the Waaaagh! fell apart in the confusion".
  • In The Dark Eye, the rare magic ritual for (past only) time travel becomes significantly harder to cast for each traveler who is alive at the destination time.

  • In the Harry Potter parody Puffs the Play, this trope is subverted and spoofed during third year when Hermione is played by a different actor in each depicted elective class. The three iterations bump into each other, gasp, and groan, "Oh, honestly."

    Video Games 
  • 13 Sentinels: Aegis Rim: Downplayed. After Android Tamao arrived at 1985, Grandma Tamao was deleted by Universal Control to prevent two of the same person from existing in the same time. However, this was the only instance of something like this happening, and characters do meet and interact with their alternate selves throughout the story.
  • BioShock Infinite:
    • Going into a universe where another "you" already exists can result in all kinds of weirdness, because the universe wants to collapse both versions into one and can't quite figure out how to do it. This gets especially pronounced if that other version of you is dead; you start blurring back and forth between states (though from your own perspective, it apparently just feels like headaches, nosebleeds, and inconsistent memories).
    • In BioShock Infinite: Burial At Sea Episode 2, Elizabeth is briefly in Columbia at the same time as her and Booker's past selves. Booker inquires what will happen if the run into themselves, but Elizabeth claims it's impossible, because they didn't last time.
  • Alluded to in Castlevania: Judgment by Aeon in his Mirror Match. He says that two of the same person cannot be allowed to exist at once in the time rift, lest time be destroyed.
  • The infamous Dr. Jekyll and Mr. Hyde game for the NES had a mechanic where if you reach the same spot where you got too stressed as Jekyll as Hyde, lightning strikes and kills both.
  • MediEvil 2: Dan goes back to the past to save Kiya from The Ripper, and after killing him, Dan meets himself as he comes in to save Kiya. They shake hands, resulting in them becoming one, giving Dan a snazzy suit of golden armor.
  • This happens intermittently in Terranigma. When the 'Dark World' Ark meets the 'Light World' one's spirit, Ark is instantly killed and reincarnated as a baby with a mixture of the Light's spirit and the Dark's memories and personality. Later, his girlfriend Elle meets the Light World version of herself... and nothing happens. In fact, for a second it seems they're about to get into a Cat Fight.
  • In Shadow of Destiny, multiple versions of the same person can be in the same room and even talk to each other without problem. Physically touching your past or future self, however, results in both of you ceasing to exist. This becomes a plot point in various possible endings.
  • In Touch Detective 3, The Cornstalker and his lab partner create a copy of Penelope, but if the original and the copy were to touch each other, the copy would disappear.
  • In the small Interactive Fiction game All Things Devours, sighting yourself - or causing your earlier self to notice anything you didn't - causes the space-time continuum to go blert with the force of a nuke. This is a problem, as the main character is trying to destroy her prototypical time machine with a range of minutes, inside a military base that nobody could infiltrate alone. Fascinating choreography, shameless Trial-and-Error Gameplay.
  • In Legacy of Kain, the moment when two incarnations of the Soul Reaver meet a paradox is created, and the resulting distortion of the timestream allows to make changes in history, which is usually written in stone, this happened four times in the games. This becomes especially important when Raziel's future self is revealed to be soul trapped inside the Soul Reaver, as said soul becomes the wraithblade in Soul Reaver, which Raziel wields - meaning Raziel is using himself as a weapon, making him a walking paradox that everyone is trying to manipulate in order to Screw Destiny in their own favor.
  • In Fate/stay night, it's explained that having copies of the same person present in the same time period causes a strain on reality that will manifest on both copies, as reality cannot truly distinguish between them. They will slowly start siphoning knowledge and skills from each other merely by being around each other, and eventually, one or the other has to go. This is compounded more directly in-story by the future copy trying to kill his past self in the hopes a Temporal Paradox will erase him from existence.
  • Subverted in one of the Sam & Max episodes, involving a lot of time travel. The duo meet their past selves from a year and a half earlier, putting them early in the previous season. It doesn't mess up the universe, but it does result in Sam and Max getting trapped in the past and having to relive the entire year and a half over again because the past versions of themselves steal the time machine.
  • World of Warcraft defies this in one quest in Dragonflight where you have to take the Hourglass of Eternity to the Bronze Dragon shrine. When you do so, your future self appears and helps you defend it from the Infinite Dragon Flight. How did that happen? The quest giver later tells you to do it again, and this time your past self appears to help you. (Given how the Bronze Dragon Shrine works, it is implied that the second quest was done to intentionally create a Stable Time Loop to send backup for the first quest.)
  • Sonic the Hedgehog has generally avoided this in his games.
    • Through the mixed-up and convoluted story of Sonic the Hedgehog (2006), this essentially takes place. There probably isn't a time where there aren't at least two Sonics/Silvers/Shadows running around at the same time, just in different locations. For example, late in the game, Sonic, Silver, and (strangely) Blaze find themselves on a cliff, while Doctor Eggman's Egg Carrier crashes into the side of a mountain, leaving Sonic to believe Elise is dead. Silver then suggests Sonic goes back in time to rescue her. While this happening, Sonic has already done so. He and Elise had already escaped the crash just as the carrier exploded. Then again, while there are multiples running around, they don't end up meeting each other, hence this trope being played straight, if unintentionally.
    • Averted in Sonic Generations. The entire gimmick of the game revolves around both Classic and Modern Sonics (and they meet up rather quickly.) In addition, there is also a meeting up of Classic and Modern Tails and Classic and Modern Eggman - who both pilot the final boss.
    • Sonic Forces sees Modern Sonic team up with Classic Sonic (now retconned to be Alternate Universe counterparts to each other, rather than the present and past versions of one Sonic). Again, an aversion as nothing bad in terms of space-time seems to happen.
  • Portal 2 has the quote at the top of this page. It doesn't seem to happen as Cave Johnson "Prime" meets and befriends "Dark" Cave Johnson, a Cave from a universe "where they breathe methane and eat asparagus" and the universe remains unharmednote 
    • Averted in the Portal 2 Game Mod Thinking with Time Machine, where the player has to bring a duplicate of their past self to the future to solve puzzles.
  • In Onimusha 3: Demon Siege, player-Samanosuke comes back in time and sees his alternate-timeline self laying slain by Nobunaga. Touching his Oni Gauntlet merges the two together and the combined power from the paradox enables Nobunaga's defeat.
  • The Journeyman Project 2: Buried In Time averts this in the beginning, as your future self meets you face to face, and sends you forward in time with his Jumpsuit.
    • However, this trope is enforced later on with Arthur, your AI companion, who copied himself into a blank biochip in your suit. Out of fear of what would happen if two of the same person met, he auto-recalls you from the time period if you try to reach his original self again.
  • Inverted in Kingdom Hearts 3D [Dream Drop Distance]. There, you can't travel through time unless you're already at your destination and you abandon your body. In this method, the selves MUST meet in order for time travel to happen.
  • Used as a plot point in Super Robot Wars Z 2, albeit with dimensional travel rather than time. Under the physical laws of the multiverse, a person cannot travel to any parallel world where a version of themselves is already present; when the heroes from SRWZ 1 travel to the new world, the Mazinger Team and the Getter Team get left behind since the Z 2 world already has the Shin Mazinger and Getter Robo Armageddon versions of them. The rest of the heroes didn't realize this until they met the parallel Mazinger and Getter Teams and started asking questions about their allies, which naturally they couldn't answer.
    • Also used with a twist in regards to the Original Generation. In the Super Robot Wars Alpha timeline, Ingram Plisken creates an incredibly powerful robot called the Astranagant; however, in the Super Robot Wars: Original Generation timeline, he instead upgrades his old R-Gun into the R-Gun Rivale, which is close to but not quite the same thing. The official reason given is that the Astranagant (and its pilot) are the Guardians of the Multiverse, so there can only ever be one Astranagant in all of existence, and not-quite-knockoffs like the R-Gun Rivale are the closest any other universe can get.
  • A non-paradox version of this in Fire Emblem: Awakening is the stated reason the Kids From The Future leave once their present selves are born; they don't want to live with their present selves because it would negatively impact their childhoods. Averted for Lucina, Noire and Severa: the first is already born and briefly meets her baby self, the second stays with her present self to right her extremely complicated relationship with her mother, and the third does leave but is said to drop by once in a while to check on her parents. Though if Fire Emblem Fates is to be believed, she eventually does leave with Owain and Inigo so they can reach Nohr. Then again, both Awakening and Fates have alternate universes within their stories, so it's likely that the Severa of one world left with her Owain and her Inigo, whereas another Severa stayed in Ylisse.
    • Played with in the Future Past DLC, since the Future Kids also don't interact with their alternate selves from another Bad Future (and one even worse than their original world) under a similar logic. They fear that their other selves, who have been even more traumatized by Grima's takeover, will end up needlessly shaken over meeting them... so when one playable Future Kid comes near his/her other self, they hide from the other and limit themselves to whisper words of encouragement for the others.
  • Some levels in The Adventures of Shuggy generate clones of Shuggy at set intervals. If he makes contact with any of his clones, he dies and has to start the level over from the beginning.
  • Surprisingly averted in BlazBlue, which most of its plot consists of time travelling. Hakumen, comes from an alternate timeline which was similar to the canon one the series takes place in, save for a few major details changed. He makes his way to the canon storyline by being flung back in time 100 years prior to the beginning of the first game and becoming one of the world's legendary heroes. His story path in the first game reveals he is the reincarnation of the series` deuteragonist, Jin Kisaragi. The two have encountered each other quite a few times throughout the series, but there doesn't seem to be any adverse affects of this trope happening. The fact that the armor is designed to work without the risk of paradoxes occurring may have something to do with it.
    • This is due to the nature of the Continuum Shift. Technically nobody ever travels through time, what they're actually doing is moving to another permutation of the "Groundhog Day" Loop - the fact they time-traveled there at all means the loop is a different one from their own. This just means that loop with have two identical, but temporally distinct individuals. It's a Mind Screw in practice too.
    • While the information isn't 100% clear, this may be what's going on between the main protagonist Ragna the Bloodedge and Naoto Kurogane. As Naoto's appearance threatens to override Ragna's.
  • Tales of Xillia 2 has this as a rule with the prime and fractured dimensions. The prime version can encounter its fractured version in one of those dimensions just fine and not suffer any consequences; however, if the fractured version encounters the prime version in the prime dimension, the fractured self disappears. In the case of Alternate Milla, her appearing in the prime dimension is what is preventing Prime Milla from reappearing. It's only when Alternate Milla sacrifices herself, that the other may appear.
  • In the Net Yaroze and Xbox Live Arcade game Time Slip, a clock will go off and a copy of your character will be created every so often, copying your every move up until the clock went up last. You must use these earlier copies to help you along the levels, but if you ever come in contact with any of them, it's Game Over.
  • Granblue Fantasy actively prevents you from creating direct paradoxes or Mirror Matches with your playable characters. If a character is fought as a boss, missing in-story, or present in the scene but unable/unwilling to help you, then you can't use said character for that specific quest. You can't use multiple versions of the same character in the same party, either.
  • Averted in Rakenzarn Frontier Story, as multiples of the same characters can be recruited as Realmwalkers. You briefly end up with a game world Mario and a cartoon Mario in the party at the same time in Chapter 3, and Donald mentions he has a Kingdom Hearts version of himself on another assignment. One of the NPCs finds trying to tell each other apart more annoying than any paradox problems.
  • Amusingly averted in Science Girls!. During the wormhole trip back home, Missy meets her future self and even gets some spare video games from her. Once the present version of the girls gets back home, they decide not to care about the possible paradox and figure the universe can survive one or two.
  • Subverted in The World Ends with You during some convoluted background happenings. When Hanekoma travels to an alternate reality, he has to avoid meeting himself, but not because the meeting itself has negative impacts; it's mentioned that Angels normally speak with themselves with no ill effects. The problem is that alternate realities happen when events happen differently, and the Hanekoma in his destination hasn't ended up in a Good/Lawful choice like the main Hanekoma has. Because Main!Hanekoma broke Angel conduct and was branded a Fallen Angel, Another!Hanekoma is lawfully obligated to apprehend him if they meet.
  • Averted in Mega Man X: Mavericks. The Zero of 21XX has no problems interacting with his 22XX counterpart. The fourth game even lets you have both in your party at the same time with no consequences.
  • In Portal Reloaded, future cubes can touch their past versions, but as soon as the past one moves an inch, the future one will disappear and have its entire timeline rectified.
  • In Five Nights at Freddy's World, if the party talks to the NPC Fredbear while the party leader is also Fredbear, a Non-Standard Game Over happens where they explode and the universe ends.
  • Daikatana: The story claims that if two Daikatanas touch, it could destroy all of existence. Unfortunately, actual gameplay disagrees if you're not playing the GBC version.
  • Zero Time Dilemma: Whenever Diana, Sigma, Carlos, Junpei, or Akane use the transporter to travel to another timeline, they always arrive in one where their alternate selves were executed in the initial vote.

    Web Comics 
  • Mostly averted in Schlock Mercenary, except that Schlock's Bizarre Alien Biology causes him to involuntarily merge with his doppelganger. Specifically... 
  • Happens in Sluggy Freelance, though for far more mundane reasons.
    "If some guy came up to me claiming to be my future self, I'd sense a setup and toss him overboard, figuring if he was me I would have expected that."
    • Meeting and hanging around with yourself in Timeless Space is generally considered a bad idea, since it means you've managed to escape once before (and returned later), and most denizens of the place would kill to find out how you did it (or to prevent their enemies from finding it out). Having a normal twin is even more dangerous, since people will just think you managed to escape, even though you never did.
  • One of the results of Gabe using a time helmet in Penny Arcade and meeting himself apparently involves reality breaking into warring shards floating in a sea of un-time.
  • One of the big issues in the first time travel arc of Casey and Andy, when several of the main characters end up back in the time when they were in high school. But it's easy to find the young Casey and Andy, since you only have to look for the biggest explosion.
  • Played straight (so far) in Sailor Sun as Honey (the Kid from the Future) seems to be unaware that her present self (Brady) was sent to live with her aunt shortly before Honey arrived in our time and it's implied that her mother may be deliberately keeping her in the dark.
  • In Persona 3 FTW, the Persona 3 Protagonist meeting his Distaff Counterpart (and making out with her) causes the Earth to implode.
  • In Captain SNES: The Game Masta, this appears in this side comic, and is explained on the next page.
  • Homestuck has no explicit taboo against multiple selves meeting each other, as long as their interactions form a Stable Time Loop. However, selves from splinter timelines are "doomed" and will inevitably be culled from existence: if you go back in time to prevent your past self from triggering the Bad Future you came from, don't expect to live long afterward.
  • In Frankie and Stein, Shelly claims that if they meet themselves in the future, their heads will explode. Later, she and Stein meet their future selves, and future Shelly disproves this theory and tells them to calm down, subverting this trope quite nicely.
  • One storyline in Dragon Tails involved the dragons travelling through time. At one point, they end up back in their forest a few years earlier, on Christmas day. Cornelius and Abijar want to go join their past selves to celebrate Christmas, at which point Enigma brings up this trope. It does not turn out as he planned.
  • The old webcomic Jamie and Nick featured the alternate dimension version. Traveling to an alternate dimension is always a bad idea, even if your counterpart is already dead. If your counterpart is alive, the universe will eventually notice and erase both of you from existence. If your counterpart is dead, the universe gets confused and gradually rewrites your memories with the memories of your other self.
  • Magical 12th Graders: Different copies of the same object cannot survive in each other's presence for long. Inevitably, the "younger" one, from the current timeline, will survive will the older one is destroyed. This applies to people as well, with the added caveat that the older copy can survive as long as the younger one doesn't realize they're the same person.
  • The Secret Knots: Discussed and averted in "Another Lydia". When Lydia meets an alternate version of herself, they hit it off well and have a pleasant afternoon together. When they part, Lydia says that she's glad that she met her, and also that them meeting didn't cause the multiverse to blow up or anything.

    Web Original 
  • In I'm a Marvel... And I'm a DC, Lex Luthor explains away a potential plot hole by explaining this trope. Lampshaded by Deadpool, of course.
  • In one episode of The Lost Cat, the narrator finds an anomaly that leads to a parallel universe, which he ventures into in search of his cat. He meets himself and they learn that his presence in a universe where he also exists is causing the anomaly to expand and potentially destroy the world. They successfully "overload the system" somehow by fining other alternate selves in other universes and jumping into each other.
  • According to Darwin's Soldiers: Card of Ten, if counterparts from the matter and anti-matter universe collide, both copies would be annihilated.
  • One important character in Meta Runner is Theo, the protagonist of the In-Universe video game Ultra Jump Mania who was brought into the real world by another character. Being outside of his game has clear negative effects on him and the Big Bad has the original copy, forcing the protagonists to attempt to send him into another copy of his video game. This works at first, but when Theo runs into the other copy's version of Theo, the game crashes and kicks the original out, and the protagonists are required to try to get the original copy back.
  • This Tumblr post describes a game of The Sims 3 in which Beavis and Butt-Head go around the neighborhood ringing doorbells and playing pranks on the people who answer. The trope comes into play when they encounter exact duplicates of themselves, at which point the game crashes.

    Western Animation 
  • The Ben 10: Alien Force episode "Paradox" has Kevin's car turned into a literal rust bucket by a time monster that ages anything it touches. At the end of the episode, Paradox gives them a new (old?) car, with the warning that it will "explode like antimatter" if it comes into contact with anything else from 1976. However, earlier in the episode, Paradox spoke to an alternate universe version of himself without any ill effects - granted, they did not shake hands or anything, but still... note 
  • One episode of Buzz Lightyear of Star Command has the heroes encounter their alternates from another dimension (where the biggest difference was that Buzz himself was evil). XR warns the team to avoid touching their counterparts — just as the two Boosters greet each other with a hug. When nothing happens, XR remarks on the trope not applying.
  • In the Futurama movie Bender's Big Score, we learn that duplicates of persons or objects created by time travel are automatically doomed, as a form of Equivalent Exchange. This becomes a plot point as we learn that Leela's new fiancee is another version of Fry, and calls off the wedding rather than subject Leela to the grief caused by his ultimate demise. And sure enough, he dies at the end in a Heroic Sacrifice. At the very end, hundreds of Bender duplicates appear and as they explode one by one, the sheer volume of temporal anomalies leads to a rupture in the universe - and a Sequel Hook for the next movie. This is almost a subversion as until time corrects the paradox by destroying the duplicate, duplicates are free to touch and interact with each other.
    Scammer Alien: I met my past self in a bar for a drink, one thing led to another, and we ended up back at my place. Or should I say, "our" place. (passionately embraces duplicate)
    Everyone Else: Ewwwww!!!
    Scammer Alien: Oh come on, you prudes!
  • Hilda: In "The Fifty Year Night", multiple versions of Hilda, Alfur and Mr. Ostenfield exist simultaneously, and them meeting each other only leads to confusion but nothing worse. It's when Hilda alters history that things start to get nasty.
  • In the season one finale of Superjail!, the Warden goes back in time to his own trial to save himself, and by the simple act of hugging his past self, causes the very fabric of reality to completely and utterly fall apart.
    "Stop touching yourself!"
  • On The Penguins of Madagascar, Kowalski invents a time machine, but a future Kowalski has come to get Private to stop him, warning him that if both Kowalskis were to ever meet, it would cause a rip in the space-time continuum. Also, a third Kowalski has come to get Skipper to keep the time machine from being destroyed. When the two future Kowaslkis meet, they reassure the others that it's okay, as long as the original Kowalski doesn't see them. And that's when original Kowalski sees them, causing the space-time rupture that led them all here in the first place. The present Kowalski jumps through the time machine portal to convince Private in the past to stop him, which the first future Kowalski notes is how he got here, and then said future Kowalski jumps into the portal next upon realizing they've made a Grandfather Paradox to tell Skipper to keep the time machine inact, which the second Kowalski notes is how he got here, completing a Stable Time Loop. Rico then stops the space-time rupture by throwing the time machine into the rift, which fixes everything. The twice-temporally displaced Kowalski is left spluttering that what he just did breaks the laws of the universe, but as far as the other penguins are concerned they've solved the problem and there was plenty of law-breaking already and they go about their business.
  • In Taz-Mania, Marvin the Martian's team-up with Taz. For whatever reason, hooking Taz up to some big gyroscope thing allows him to spin them through time. Marvin is always cautioning him not to meet himself, as "It results in an Earth-Shattering Kaboom." Of course, he forgets this advice. The result was somewhat similar to the ending of that Tiny Toon Adventures episode where Buster, Hamton and Plucky drank beer.
  • Another Looney Tunes short has a humorous non-time travel invocation of the trope. Playing hide and seek with Prissy's little "egghead" son, Foghorn Leghorn hides in a storage bin. The young genius plays with a slide rule, scribbles down some calculations, marks an "X" on the ground, and proceeds to extract Foggy from that very spot with a shovel. Foghorn protests, but the little Einstein just points to his calculations. As the scene ends, Foggy passes the bin in which he had hidden, and starts to curiously lift the lid, but stops himself.
    Foghorn: No, I'd better not look. I just might be in there!
  • In the DCAU, specifically in Justice League, this is the explanation used by the future Vandal Savage for why he doesn't go to the past and stop himself from destroying the world in Hereafter; considering that Vandal Savage is an immortal caveman who has lived out virtually all of human history, that means he effectively can't time travel at all. He specifically says that it's a result of his particular time machine's design rather than an immutable law of the universe. In fact, Batman travels to the future and meets the Batman Beyond version of himself in a later episode, with no consequences. Admittedly, time outright collapsed in that episode, so "no consequences" is a bit of a relative term. In the short term, at least, it turned out fine, and the collapse was caused by Chronos messing too much with time, not by the Bat-selves meeting.
    • For the same reason, in The Savage Time the present Vandal Savage was unable to go back in time to take over the world. Instead he sent back a laptop informing his past self how to do so.
    • The Batman Beyond version of Batman had no recollection of his younger self's perspective of their meeting or the events that led to the meeting. That said, the timestream was already pretty much in flux by that point for unrelated reasons.
    • Static traveled to Batman Beyond and briefly met his future self. No Earth-Shattering Kaboom, and his future self didn't seem the least bit surprised.
  • Bump in the Night: Mr. Bumpy unwittingly insulted Squishington, who locked himself away as a result of it. Bumpy then went back in time to prevent that but failed. Then he went back again and failed again. The three Bumpys then got an advice from Future Squishington and apologized to their friend. When Squishington asked the Bumpys why there were three of them, they disintegrated because they couldn't agree on which ones had to leave.
  • In the Fantastic Four: World's Greatest Heroes episode "Out Of Time", HERBIE frantically reminds Susan, Ben, and Johnny of this rule, alleging that "the universe could implode!... or something" if it's not followed.
  • Gargoyles: When David Xanatos went back in time to set the events that would lead to his past self receiving the ancient coin he sold in order to have the money to start his fortune, Demona went back as well and tried to persuade her past self into a Face–Heel Turn earlier than she did in the original timeline. She failed but claimed she remembered that meeting from her past self's point of view and stated the past couldn't be changed.
  • Pinky and the Brain received a visit from their future selves with a plan to go to the future (a future ruled by cockroaches) to steal a kit to take over the world. Not only did the plan fail, as usual, but they ended with several Pinkys and several The Brains.
  • Kim Possible: In "A Sitch in Time", when Kim defeated Drakken, Killigan and Monkey Fist, Shego got a visit from her future self, who advised her to steal the time monkey and use it to take over the world. Past Shego first assumed Drakken cloned her.
  • Lilo & Stitch: The Series: As revealed in "Melty", Jumba invented a time machine and installed a paradox inhibitor to prevent its users from meeting past selves. The users would basically rewind time. Lilo and Stitch once forgot to use the inhibitor and met their past selves but no disaster seems to have happened from it.
  • The Fairly OddParents! had three episodes of this instance:
    • "Father Time" had Timmy and his fairies travel back to the 1970's. Timmy found out a young Bill Gates was Cosmo and Wanda's godchild. Cosmo and Wanda met their past selves but nothing bad happened from it. When he was back in present time, a future Timmy showed up with his Cosmo and Wanda, destroyed the remains of a trophy and told present Timmy he'd thank him for it. One can only wonder why.
    • "The Secret Origin of Denzel Crocker" had Timmy and his fairies going back to 1972 and Timmy found out Cosmo and Wanda were Crocker's fairy godparents back then. It's unknown if past Cosmo and Wanda recognized their present selves, but past Jorgen recognized present Jorgen.
    • "Channel Chasers": Coming from a Bad Future, an adult Timmy went back to his childhood to prevent Vicky from taking over the world.
  • In The Smurfs (1981) episode "No Time For Smurfs", Handy accidentally creates temporal copies of himself, Brainy, Clumsy, and Smurfette when they mess around with Father Time's Sands Of Time hourglass by first causing time to go backwards and then causing time to repeat previous events such as their discovery of Father Time's workshop. Averted in that nothing disastrous happens, but the temporal copies do inform Papa Smurf that they have seen what they think are copies of themselves in a cave. Fortunately, by the end of the episode, Father Time and Mother Nature straighten the whole mess out, and the temporal copies vanish.
  • In an episode of Chowder, Mung Daal and Chowder travel back in time to correct a cooking mistake Mung made as an apprentice, where Mung insists that they not interact with his past self to avoid space-time from unraveling. Naturally, Chowder doesn't listen and brings Mung's past self back to the future with them, wiping out their entire universe (not that it sticks).
  • Inverted in Totally Spies!, where the three Spies are jaunted twenty-years into the future, and can interact with their adult selves safely, and good thing too, because they have to rescue them from the now-villainous Mandy.
    • Played more straight, and probably invoked in an episode where Time Travel is used for the villain to manipulate Jerry in the 70's into committing robberies through time and ultimately change history. In the climax, he gets the idea to have the Spies travel further back before he can meet with the villain, and bring him into the other timeline. The two selves making contact results in a paradox that restores everything back to normal.
  • This Trope is defied in the Dexter's Laboratory movie Ego Trip, where the Dexter everyone's familiar with uses his time machine to form a team consisting of himself and his Teenage, Adult, and Elderly selves to Set Right What Once Went Wrong, courtesy of Mandark's tampering. There was no Earth-Shattering Kaboom, despite the fact that Mandark used the same trick to fight them. In fact, after Dee Dee intervenes, she accidentally crates a future utopia.
  • In the Codename: Kids Next Door episode "Operation: F.U.T.U.R.E.", this is Zigzagged. The villain was apparently able to create the Bad Future not only by doing this intentionally, but by keeping in regular contact with her future self. On the other hand, Numbuh Four's future self did speak to him after giving the rest of the team vital information needed to Set Right What Once Went Wrong, but he never told them who he was. And given what is revealed in the Series Finale, it would seem that this future timeline is undone completely, and Numbuh Four's future is changed.
  • Sonic the Hedgehog (SatAM): In "Blast to the Past", Sonic and Sally travel back in time and meet their past selves. Nothing bad happens from this and the past selves don't know who they really are.
  • King of the Hill referenced this in one episode, where Dale mistakes one of Kahn's relatives for a time traveler (due to his high-tech car, and thinking that the military time clock was showing the year) and thinks that he was sent one day in the past. He believes that seeing his past self will cause the planet to explode since space-time wouldn't comprehend it. So he spends the day doing things that he doesn't like to supposedly lower the chance of seeing his other self, before coming to the conclusion that he'll run into himself in his bathroom since he refuses to use any other than his own.
  • Penn Zero: Part-Time Hero: In "Back to the Past of Future Balls", all characters who go back in time wear disguises to avoid being recognized by their past selves. The good guys wear fake mustaches and the bad ones wear fake beards.
  • In the Sonic Boom worlds, having two of the same individual in the same dimension will eventually result in a universe-destroying paradox. This was first discovered in "Two Good To Be True" as a result of two versions of Knuckles hanging around. Later, in "Where Have All The Sonics Gone?", Morpho made sure to send their Sonic to a dimension where there were no other Sonics to avoid this happening. Later, when Shadow decides to "to heck with everything" in "Eggman: The Video Game", he intentionally takes Eggman and his Lord Eggman counterpart prisoner in order to create an anomaly.
  • The Secret Saturdays once encountered their evil counterparts from a Mirror Universe, apparently made of Antimatter, that caused physics to get weird whenever they were in close proximity to their doubles.
  • Hilariously averted in the episode The Last Christmas in DuckTales (2017), where Scrooge greets his past self in a Christmas party with a casual gesture, and likewise for his past self. Paradoxes are brought up however, which indicates this trope is still in effect, but Scrooge time travels so much that he actively expects to meet older and younger versions of himself.
  • Final Space: Discussed and averted in episode 7, when Quinn meets her future self Nightfall. Quinn asks Nightfall how the two of them being in the same time and place doesn’t cause a universe-destroying paradox. Nightfall doesn’t know, other than that thing apparently don’t work that way.
  • Inverted in the final episode of Xiaolin Showdown. After Omi's time-traveling creates a Bad Future, the warriors intentionally seek out Omi's frozen past self, to wake him to meet his future self, creating a paradox that resets the timeline to what it was before.
  • Wander over Yonder: One episode has Wander and Sylvia accidentally get time orbble juice which sends them running through time; they first end up in the episode "The Picnic" from Season 1. Although he's eager, Sylvia tells Wander to stay away from his past self to avoid creating a time paradox.

    Real Life 
  • This is literally the case with fermionsnote . Two of the same fermion cannot exist in the same place. It's inverted with bosons, which are more likely to exist in the same place than predicted by chance. Time travel is unnecessary here, since the way quantum physics works, any two particles with the same properties are, in fact, the same particle. Interestingly, since chemistry is based on this fact, somehow getting ahold of truly different electrons would be disasterous, if far from reality-destroying.
  • Using special relativity and the last comment, it's easy to make this situation happen in real life, and show that it's not a problem. By moving one particle faster, it can be made to pass through time at a different rate. Since both are the same particle, but more time passed for one, then one of them is a future version of the same particle. They interact as normal, showing that they are, in fact, the same particle, and being Just One Second Out of Sync is not an attribute that exists on a fundamental level.


Video Example(s):

Alternative Title(s): Never Shall The Selves Meet



After seeing Theo glitching out in the real world, Tari and MD-5 try to get him into their copy of Ultra Jump Mania to keep him safe... only for the Theo from the MD-5 copy of the game to notice the other Theo and cause the game to collapse and boot them both out.

How well does it match the trope?

5 (4 votes)

Example of:

Main / NeverTheSelvesShallMeet

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