You Already Changed The Past - Television Tropes & Idioms

Our presence here doesn't alter history. You and I meet here because we are compelled to - we have always met here. History is irredeemable. Drop a stone into a rushing river - the current simply courses around it and flows on as if the obstruction were never there. You and I are pebbles, Raziel.

—Kain, Legacy Of Kain: Soul Reaver 2

You go back in time to Set Right What Once Went Wrong, only to discover that the "changes" you're making to the past are just causing things that "already" happened to happen. In other words, there was no "first time around" - the past only happened once and there were no different "versions" of it. It's like being Time's own personal Xanatos Sucker.

This does not necessarily mean that You Cant Fight Fate. You can, but only if your past self thinks the changes you made haven't happened, creating a Stable Time Loop. For example, if Bob wanted to go back in time to stop Alice's death, he would have to make his past self think that Alice still died. And, following this logic, Alice never did die - she had "already" been saved by time-traveling Bob, but he didn't know that until he went back in time to save her. (Do you have a headache yet?)

Note that You Already Changed The Past —> There Is Only One Possible Future, which is the version of fatalism found in some older works, that don't involve time travel.

This trope is notable in that it makes the most sense when considering time travel from a scientific point of view, see the Novikov self-consistency principle

. However, the number of time-travel plots that it allows for are extremely limited and the logic gets complicated very quickly.

Thus, most time travel stories that involve altering the past will provide some of the characters with Ripple Effect Proof Memory. This makes less sense, but it makes for a narrative convenience. If a You Already Changed The Past plot is used, the time travel will probably be a one-off thing, since repeating it would most likely get tedious.

Nitpick: Novikov's self-consistency principle is Older Than They Think. It was named "the Law of Conservation of History" by Larry Niven in his short piece "The Theory and Practice of Time Travel," published at least ten years prior to Novikov's work. Of course, Larry Niven is a Science Fiction writer, which may explain why nobody cares. Alternatively, this is an illustration of something called Stigler's Law of Eponymy

: nothing ever gets named after the first person to discover it.

The Ancient Greeks and Vikings loved the notion that You Cannot Change The Future, and their works heavily imply that they believed in this specific notion of time (which even the Gods were trapped in). Although they used predictions rather than time travel, the effect is the same. Many first-time readers of the classics who don't buy into this notion of time, or don't realize this is why You Cant Fight Fate in the classics, have a hard time accepting The Fatalist behavior of classical Greek and European heroes.

See also Self Fulfilling Prophecy.

Examples:

Anime and Manga

Urusei Yatsura has time travel in a few occasions.
- In one, Lum goes into the future where she brings back Ataru's diary. He reads it and believes things will go right for him, but attempting to cause them makes everything go horribly wrong. It's later found that when writing the entry about everything that went wrong, his tears blur the ink, causing it to look like he wrote about things going well.
- In the other, the cast goes back in time to prevent Mendo from getting claustrophobia and nyctophobia. As a result, young Mendo pisses off the modern Mendo, causing him to attack his younger self. While hiding from his older self, young Mendo was trapped in a dark jar, causing him to grow deathly afraid of dark and tight spaces.
Tsubasa Reservoir Chronicle. Details would be massive spoilers, but suffice to say that time travels differently in different universes, and something the heroes do midway through in a world that later turns out to be their own past sets up the very premise of the story, as revealed in the finale.
- Also, one character who pulls a Face Heel Turn halfway through is fated to pull a Heel Face Turn back, given that his future self is the protagonist's father.
In Rave Master, after much time is spent freaking out over what horrible ways they've twisted the past, Sieg, Elie, and Haru (but mostly Sieg) discover that all there actions caused the future they were trying to protect by not taking those actions. Haru made it very clear to the knight that the criminals he brought had invaded the castle ten days earlier, and that the knight was to take credit for catching them, which we see him talking about at the time Haru gave 50 years later. Getting Resha kidnapped enforced the king's decesion to have her fake her own death, leading her into the future where she get's amnesia and meets Haru, and ditching Sieg in the past leads to him being there to set the whole time loop up and make sure they mess with the past like they're supposed to.

Comic Books

A fairly recent Blade series had Doctor Doom lure the Daywalker to his castle, where Doom then proposed Blade with going back in time and saving his mother from a vampire attack. Blade asked him why he should do it, and Doom replies with "Because I've already seen you do it in the past." Doom is nice enough to give him a serum which would suppress his bloodthirst though.
A recent issue in The Mighty Thor series had an storyline where Loki sends himself back through time with the aid of Hela to accomplish certain tasks that had already been mentioned in a previous issue, but with certain details left unclear. Turns out that Loki was responsible for many of the major events in Asgardian history, but it's left unclear whether they still would have happened had he never gone back in time. Even he isn't completely sure.
- He lampshaded this trope, saying that he cannot change a past and make future comes different way, but he can make sure it will go a way it did.

Film

Twelve Monkeys, as well as its inspiration, La Jetée.
The Terminator gives a rare example of the good guys directly benefiting from the immutability of time. The machines sent back a Terminator to kill Sarah Connor before her son John Connor was born, in response, the rebels send back... the guy who becomes John's father.
- Also, in a deleted scene, it turns out that Cyberdyne, the company that built Sky Net and the original Terminators, acquired the remains of the Terminator. The sequel shows that they'd begun reverse engineering the Terminator, which would presumably have led to the creation of the Terminators had the events of the sequel not occurred, so it happened on both sides.
Harve Bennett's explanation for why the Enterprise crew was so careless about altering history in Star Trek IV The Voyage Home seems to be (he says it in a rather disjointed way) that this trope is in place and the characters are Genre Savvy. Although this contradicts how time travel is usually portrayed in the series, it does fall into line with the one episode of the original series that also used the "slingshot around the Sun to visit 20th century Earth" method.
- In the reboot movie Star Trek, 200-something years in the future, Spock fails to save Romulus because he doesn't get there in time, and he and Nero and his crew are sent back to the present. Nero, in revenge, destroys planet Vulcan, which Spock Prime tells Kirk was because of his failure to save Romulus. So, Spock(presumably) now knows his failure to save Romulus in the future was what caused the destruction of Vulcan in the present, so, when the time comes, he can simply leave for Romulus earlier, to make sure he gets there in time, thus averting the destruction of both planets. But, if he averts these events, there's no way for him to know he should leave for Romulus earlier, and-Oh, God, I've gone cross-eyed.
- This movie runs on the parallel-universe model of time travel. Romulus is destroyed in the original Star Trek universe where all the previous series and movies took place. The time travel causes a new universe to branch off, in which Vulcan is destroyed but Romulus presumably won't be. If someone from the reboot universe goes back in time to before Vulcan's destruction to tell Spock to leave earlier to save Romulus, then both planets will be saved in the resulting universe.
  - But the problem with that theory is that Nero arrived in the TOS time line twenty-something years before the destruction of Vulcan. He destroyed Kirk's father's ship, remember? The ball was in motion before Kirk was even born, and Spock would presumably have been at least in his youth by then.
This gets covered regarding the movie Happy Accidents very well here.
This is a central theme of brilliant Spainish Mystery thriller Time Crimes.
In Deja Vu, the first few attempts at actually changing the past just end up causing things the characters and audience have already seen happen. Eventually, for the sake of having a happy ending, they do manage to make a change that works.
An interesting case is the movie Paycheck. What happens to the protagonist (he is administered a procedure which would erase all of his memories from the coming two years; when he is finished, he's told these two years already happened) would be a perfect example of this trope. Only there's no time travel (though the plot revolves around a future-seeing machine).
In the 2007 film Premonition, Sandra Bullock lives the week of her husband's death out of order. She's unsuccessful in her attempts to save him, as on the last day she accidentally causes his death by preventing another one.

Literature

There Will Be Time by Poul Anderson. A substantial number of humans have had the innate ability to Time Travel since before recorded history (possibly because it was inserted into the genome by future travelers). So little of human history is known exactly, and the book's scope is so great (from Jesus' crucifixion to a far-future postapocalyptic revival of civilization—at least) that the inability to change the past comes up only rarely—but the protagonist is nearly broken when his Byzantine wife dies of an illness because other travellers have abducted him to the future.
Eoin Colfer's Artemis Fowl Time Paradox The matter is discussed before they actually Time Travel and Artemis presumes that whatever happened in the past cannot be changed. It turns out he's right. It also lets a huge variety of crazy actions take place.
Diana Gabaldon's Outlander series runs into this a lot.
The Door Into Summer, by Robert Heinlein. Various instances of Human Popsicle, but more importantly a weird time machine that has an equal chance of throwing the subject forward or backward. The protagonist uses it knowing he HAS to be sent backwards. Bonus points to a throwaway gag that suggests that Leonardo da Vinci is (and always has been) an accidental time-traveler.
In Aunt Maria, by Diana Wynne Jones, the main characters go back in time in the form of cats to stop Anthony from being imprisoned underground. He ends up tripping over them and falling into the trap.
Dragonriders of Pern
- In Dragonflight, F'nor returns from the past to warn his friends that an expedition they're planning is going to fail. Unfortunately they now know that if they don't go it'll create a paradox because the guy who warned them won't come back in time to warn them... so his warning has exactly the opposite effect. Knowing they're going to fail they have to set out anyway.
- And of course we have the situation where there are too few riders in the present due to many of them having suddenly disappeared in the past. So someone travels into the past to gather some more, thus causing the shortage. (Although it's not as futile as it sounds because their numbers would have declined anyway due to a coming period of long inactivity. This way their disappearance is useful.)
  - This is without even mentioning events from a more recent novel in which a Gold somehow randomly jumps to a few centuries in the past after being given a BAD mixture of gene-altering medicines in an effort to cure a plague running through the dragons themselves, which results in said Gold crash-landing in a time when one of the last trained geneticists is still alive, thereby resulting in the creation of aforementioned medicines when they would not have otherwise been made, but had already been made anyway because in the past the sick dragon had already crashed....good god my head hurts.
  - And even THAT ties back to the original trilogy of books by establishing, at long last, just what the 'Ancient-timers' room was made for, and what the colorful diagrams REALLY were.
- Also noteworthy is the climax of All the Weyrs of Pern, where the AIVAS reveals to Jaxom that two of the three antimatter charges used to divert the Red Star from its orbit have to be placed in the past in order to have the proper effect, and that those past explosions are what caused the so-called Long Intervals in which Thread did not fall. Of course, if those hadn't occurred, none of the events of those books would have occurred either, including the discovery of the AIVAS itself.
Tim Powers plays with this trope a lot in The Anubis Gates. The time-travelling protagonist comes to believe that You Cant Fight Fate, then learns that it's not that simple, since historians don't know all the details.
- He encounters the brand-new original manuscript of a poem he'd studied in his own century, and wonders how it would pick up the stains he'd seen on it in his own time. A poet he recently met then walks in carrying some food, puts it down, and picks up the manuscript with his greasy hands to look it over.
- He encounters a 17th century book with an inscription in it that shakes him up. He later travels accidentally to that century, and on encountering the then-new book, writes the pig-Latin inscription addressed to himself that he would read in the future.
The climax of Harry Potter and the Prisoner of Azkaban. They go to the past to save Buckbeak and Sirius, and Harry wants to see a mysterious figure that he believes to be his father. Buckbeak never died, the thumping sound was the executioner taking his frustration out on a fence (pumpkin in the movie). The mysterious figure was Harry from the future saving himself, his dad really is dead. Then they save Sirius, who rides off with Buckbeak. Plus they hear a couple strange noises, which turns out to be their time traveling selves.
To Say Nothing Of The Dog by Connie Willis involves time traveling historians (which first appeared in her Doomsday Book)who spend a lot of effort to repair the "incongruity" caused when one of them inadvertently brings a cat forward from Victorian England (they're extinct in 2057). This involves trying to make sure that the cat's owner winds up with the "Mr. C" that her diary specifies after they've accidentally introduced her to a different man. It turns out that all perceived incongruities are the continuum's self-correcting system.
Time Travel in the Pliocene Exile novels works this way. Of course, since Time Travel must take you back six million years (and then only works in one spot in France), it's rather difficult to know exactly what the time travelers already did.
Used extensively in Suzumiya Haruhi this seems to be the whole purpose of future(er) Asahina. Who is suspected to be the superior of Present(or rather not-so-future) Asahina, and puts her younger self trough all the missions and trouble she already went trough herself. So she already changed the past because she will order herself to go to the past and change it so she can get to the future and order herself to change the past.
Minor example in So You Want To Be A Wizard by Diane Duane: Nita and Kit are stopped for a moment on their way to a world gate by a loud bang on the other side of a door they are about to open. It turns out at the end of the book that it was Nita herself, coming back from the future a little earlier than planned and trying to avoid meeting their younger selves.
This was true in the novel The Time Travelers Wife by Audrey Niffenegger. The main character was constantly going into both the past and future, but everything was pre-set. Everything he did when he went into the past, he had "already done", and once something happened, he could never change it; in situations where he already knew what was going to happen, he had to act in the way he had already acted, he didn't have any choice.
Douglas Adams' The Hitchhiker's Guide to the Galaxy universe works this way. in the second book, The Restaurant at the End of the Universe, while stranded on prehistoric Earth with an exodus' worth of incompetent aliens who are plainly going to begin colonizing, Ford Prefect tells Arthur Dent "This doesn't change the past, this is the past."
Isaac Asimov's short story "The Red Queen's Race" has a character who tries to make this trope happen. He was asked to translate several modern books on physics into ancient Greek, with the work being beamed back into humanity's past. History fails to change because the translator was very careful to leave out most of the advanced material.
- Specifically, the translator only includes information which would account for discoveries and advances already present in our own timeline.
Unborn Tomorrow, a short story by Dallas McCord Reynolds. A wealthy man wants a private eye to locate a time traveller from the future and get the secret of eternal life. He believes such time travellers would go to the Oktoberfest, where everyone would be too drunk to notice anything strange about them. The secretary is surprised when her boss curtly turns down this chance to get drunk on someone else's money. The private eye explains that he's already taken the assignment three times, and each time the time travellers sent him back to this point in the timeline, with a massive hangover from drinking too much German beer. There's no way he's getting another hangover piled on top of the previous three, not for any amount of money!
The Skull by Philip K Dick. An assassin is sent back in time to kill the founder of a church, only to realise that the Founder is himself — the 'miracle' that inspired the church was him appearing after he'd been killed (he'd arrived at the wrong point in time) thus 'coming back from the dead'.

Live Action TV

Star Trek The Original Series ("Assignment Earth")
Early seasons of Andromeda used this, but it degenerated into Timey Wimey Ball territory after a while.
The first Time Travel episode of Stargate SG-1 ("1969") followed this logic, but no subsequent Time Travel episodes did.
- The two-parter "Moebius" conspicuously did the opposite - they changed history twice, but ended up following the title of this trope, in that as the heroes are considering going back in time to steal a ZPM, they discover that previous versions of them already stole it, and sent it to them by The Slow Path.
- Actually, "1969" does use the same time-travel conventions as Moebius (and the Continuum movie). The difference is that in "1969" we only see one iteration. (Moebius shows alls three). To explain... in the original timeline, there was no SG-1 in the past. In the present, they vanish and arrive in 1969, starting the second iteration. They are arrested and unknown events occur, but likely they never make it back to the present. When this timeline reaches the present, however, Hammond (who was in 1969) now recognizes them and realizes something is going to happen and writes himself a note to be put in Carter's pocket. So this time SG-1 is set free, but still doesn't know about the solar flare issue and is still likely stranded, but somehow recontacts Hammond and tells him this, resulting in ANOTHER iteration wherein he also provides this information. And this continues until we have the final episode we see, which is the first iteration where everything actually worked out right. Albeit, this explanation is more complicated, but it does make the Stargate time-travel conventions more consistent.
  - Mobius and Continuum use the same time travel methods as 1969, not the other way around. The only reason they trigger alternative iterations of the time line is because something changes. In 1969 no one in the past ever tells Hammond 'Hey, George, don't let us go on this mission on <Date>, we'll end up back in time.' Since nothing has changed, the timeline doesn't change. It's a Stable Time Loop, but only by virtue of no one poking it and causing it to destabilize.
  - Though the episode "2010" does subvert this trope, unless you consider 99% of the episode to be the second iteration of the Stable Time Loop. In that one, the now-retired members of SG-1 discover that supposedly benevolent aliens have actually sterilized most of humanity, as part of a plan to turn them into a pastoral world, turning Earth into a massive farm for the aliens. SG-1 manages to send a message back in time to warn the SGC not to go to the planet the aliens live on, thus changing the timeline. Of course, they just run into the aliens later on at a different planet, so this maybe makes it more like the Terminator 3 example.
In the Murder Most Horrid episode "A Determined Woman", a female scientist working on a time machine becomes so frustrated with her idiot husband's antics that she kills him. Several years later she is released from prison, finishes her time machine and goes back to try and save her husband, only to find that his confusion between the two versions of her is what caused his erratic behaviour in the first place.
After Hobgoblins, a particularly loathsome film, was shown on Mystery Science Theater 3000, Tom Servo tried to go back in time to stop the movie from being made by hunting down the director and... kicking him in the shin. Upon Tom's return to his present, Crow pulls up an article where the director claimed that his inspiration for Hobgoblins was that time when a squat red robot ran up to him out of the blue and kicked him in the shin...
This is actually done multiple times in the Doctor Who universe (as are most time travel theories).
- In the series 4 episode "The Fires of Pompeii", The Doctor doesn't want to avert the destruction of Pompeii, is convinced to avert it anyway, and then is forced to cause the disaster in order to avert a larger catastrophe.
- The rift in spacetime that already exists in Cardiff is created by the Doctor's actions in "The Unquiet Dead".
  - And in series 5, the crack in the universe that's been causing so much trouble turns out to have been caused by the TARDIS exploding. Fortunately, the crack transcends space and time so much that it extends back before the event which caused it, allowing the Doctor to nip through and place the TARDIS on the other side of the crack, thus preventing the end of the universe. That's once he's Tricked Out Time in a variety of ways in order to get himself out of that bloomin' Pandoricon. Usually (well, seven times out of ten) he's a stickler about not interfering with your own timeline, but desperate times call for desperate measures.
Inverted in Farscape. Sent back in time and desperate to keep things the way they were, the crew screws up, with each attempt to force what they know to be history resulting in the present timeline getting worse. In the end, rather than the noncombatant survivors of the battle being spared in a hasty but well-regarded treaty, they are butchered by enraged enemy soldiers. The memorial to peace becomes a lament of the senseless slaughter.
Crime Traveller had this as a central point, in theory. In practice, everything about the show's time travel suffered from galloping They Just Didnt Care.
The only time-travel arc on Babylon 5 involves this trope, and it is absolutely central to both the Myth Arc and the background mythology of the show. Babylon 4 appears in Babylon 5 space four years after it disappears (the episode "Babylon Squared." The events leading up to that appearance are explained in the two-parter "War Without End," in which we find out that Babylon 4 was taken to the year 1260 AD (or so) to help the Minbari and their allies gather to fight the Shadows. To prevent this from happening, the Shadows sent a big bomb to Babylon 4 just as it was about to come on line in 2254. However, the White Star also goes back in time (because Delenn, Sinclair, Sheridan, and Ivanova see it in a recording), destroys the bomb, and (as it turns out) takes it back in time as well. However, this is not before the time device (sent by Draal and transported by Zathras) malfunctions, dropping Babylon 4 into 2258, leading to the events of "Babylon Squared." Sinclair then realizes that he must take Babylon 4 back in time himself, and then uses the triluminary device to turn himself into a Minbari—specifically, Valen, who led them in the First Shadow War, organized their society, and effectively became the main prophet of their religion.
This concept became a major plot point in the fifth season of Lost (which Hurley couldn't quite grasp) though it was put to the test in the cliffhanger finale...
- Particularly annoying with Sayid shooting young Ben, which was not only implied to have already happened, Kate and Sawyer's interference in order to put things right seems to actually have caused Ben to become evil, as Richard says that because the island healed him he would always be "one of them" and that he would "lose his innocence". So by trying to kill him, they effectively caused what they were trying to prevent. Nice going, guys!
  - It appears that while they can't change their OWN past, they can create a new timeline, but they remain stuck in the original, time-loopy, one.
  - Disregard that last comment -epic spoilers ahoy- That isn't an alternate timeline, it's the afterlife, an indeterminable amount of time after the events of the series.
Quantum Leap was somewhat inconsistent on this trope. In episodes that directly impacted Al or Sam, they would have the entire memory of both things happening. For example:
- Sam successfully tries to save his brother's life in Vietnam, which alters history and results in Al becoming a prisoner of war.
- In one episode, Al is on trial for something and the judge is giving him a hard time. At the same time, Sam is in the past helping a young female attorney. After Sam's work is done, Al is on trial with a female judge. Al has the memory of the male judge and is surprised by the switch.
In the Outer Limits episode "Tribunal", history professor and Holocaust scholar Aaron Zgierski is taken back to Auschwitz by time-traveller Nicholas Prentice (who turns out to be Zgierski's own great-grandson). While there, they rescue Aaron's "older" sister (who is only eight at the time) by bringing her into the future to live out her life free of Nazi oppression. History recorded Aaron's sister as dying at Auschwitz after being "dragged away" by a couple of guards, who were actually Zgierski and Prentice in disguise.

Mythology

As mentioned, Greek and Germanic mythology tended to hammer on the idea (relying on prophecies instead of time travel) that You Cannot Change The Future. Even the Gods can't change the outcome of the story. (How many steps is Thor destined to take in the final battle of Ragnarok?) Not only that, but historians actually posit that Viking culture went into a prolonged funk over it, presaging the rise of Ingmar Bergman and Werner Herzog by centuries. (The lack of sunlight in wintertime didn't help.) Vikings in particular lamented the decline in pagan beliefs for exposing them to the horrors of existentialism, making them less resigned to the inevitability of death in battle. Meanwhile, the Greeks preferred to set up stories where characters would have hubris enough to believe this trope did not apply to them, and then brutally swat them down in order to provide an entertaining Aesop. For examples, see You Cant Fight Fate and Self Fulfilling Prophecy.

Video Games

Legacy of Kain uses this as an important plot point; more than one character has goals achievable only by finding ways to subvert this. Interestingly, while two entire games in the series take place in the past, while this trope is in effect, it still manages to have one of the most complicated sets of Xanatos Gambits ever. One of the protagonists is himself a walking subversion, and thus finds himself endlessly manipulated by pretty much everyone, because he's the only one who can alter time in their favor.
Kain: "Suppose you flip a coin enough times. Suppose one day... it lands on its edge."
- Interestingly the first game in the series (Blood Omen) used a different kind of time travel - the kind where you go back, do something, and return to the present to find the effects of your actions having taken place. This was played straight with no mention of the paradox that would ensue from this kind of time travel. Two games later when time travel was reintroduced as a much more significant plot element, the rules were established around this instance of time travel, and it turns out Kain's original trip back to the past, as depicted in the first game without RetCons, already met the criteria for how someone can achieve a true alteration to the timeline.
Final Fantasy VIII ending has this trope, with Ultimecia giving her sorceress powers to Edea in the past and Squall suggesting the SeeD idea at the same moment, setting up the organization that Squall is raised by.

Web Animation

A three-part episode of Red Vs Blue had Church travel back in time and try to change history to prevent both his 'death' and that of Tex, as well as attempting to stop the other difficulties that the Blue Team had to encounter at the time (such as the problem with Lopez's switch, and Tucker getting blasted by an RPG). He ends up accidentally causing, or failing to prevent, every major event of the series up to that point including his own 'demise'.

Web Comics

All the Time Travel in Bob And George eventually resolves itself into this.
8-Bit Theater has been explained by an in-comic character to be this, with the added You Cant Fight Fate.
- At least, that's what the character believes. The character with enough nigh-omnipotent abilities to force things on the track he remembers.
In Sluggy Freelance Bun-Bun's whole adventure in Timeless Space was based off this trope. As Uncle Time put it, "Life's so much funner with the paradox rules turned off."
In Homestuck, only Dave, the Knight of Time gets to go back in time and create Alternate Universes. Everyone else, no matter how much they've screwed around with the timeline, can only make Stable Time Loops, and the Trolls regularly insist that they've already lost the game and that You Cant Fight Fate. It probably helps that all in-universe timechanging items have built-in failsafes against causing paradoxes.

Western Animation

Played straight on Futurama, where Fry ends up in 1947 and spends half the episode just trying to make sure his grandfather doesn't die. After the professor warns him not to change the past unless he was already destined to change the past, Fry's extreme caution and stupidity result in his grandfather being vaporized by an atomic bomb. However, subsequent events make it clear that the man Fry killed was not actually Fry's grandfather, and that his real grandfather is Fry himself.
The standard rule for time travel in Gargoyles.
- Goliath tried to convince Demona in the past not to turn evil, and she at first takes it all to heart. Turns out things change, she remembered the encounter and came to the conclusion Humans Are Bastards anyway.
- Xanatos uses this to his advantage. He gives two period coins to the Illuminati, along with a letter. The coins are like pennies in the past, but by the present they're very valuable and are the coins that started his fortune. The letter of course, is to tell him to do just that.
- Later, Goliath attempts to use the time-travelling Phoenix Gate to save Griff from being killed during the Blitz in WWII London, after being accused of abandoning or murdering Griff by his companions. With incident after increasingly improbable incident occurring that indicates the universe has decided Griff is its new Chew Toy, Goliath ultimately concludes that fate will not allow Griff to get home and uses the Phoenix Gate to bring Griff back with him to the present, thus causing his original disappearance.
- Mid-way through the Avalon arc, the Arch-Mage tutors his past self on how to become his present self. He also explains why the weird sisters showed an interest in Mac Beth and Demona (He told them to show an interest), and how he averted his Disney Villain Death. At the episodes conclusion, the past-self goes back to become a teacher and his present self gloats about his plan.
- Goliath winds up in a Bad Future (really All Just A Dream), and Elisa keeps egging Goliath on to use the Phoenix Gate to fix things. This is a hint that Elisa isn't what she seems, as by now, she should know how the Gate works.
Used on an episode of Justice League Unlimited. Brainiac 5 imports heroes from the past because history mentioned an incident where heroes traveled to the future. He tries to avoid mentioning how it turned out, of course, just to be sure things go the way they're supposed to, with only two of the three returning.
In the Darkwing Duck episode "Paraducks", Gosalyn warns Darkwing not to interfere into the past when they went back in time to his childhood. At first he doesn't and returns to the present, only to find that S.H.U.S.H. doesn't exist, the King, a two bit thug from Darkwing's childhood has taken over St. Canard and he serves as the King's cowardly lackey, never became Darkwing Duck. They go back and time and shut down the King for good and give little Drakey Mallard (Darkwing) the courage he needed.
The Fairly Oddparents special "The Secret Origin of Denzel Crocker": Timmy and 21st-century Cosmo were the ones responsible for making Crocker lose his fairy godparents and giving him the opportunity to partially get around the ensuing mass mindwipe, which also indirectly led to his own birth due to the disappointed scientists at Crocker's presentation in the '80s investing in Dinkleburg's parachute pants and causing him to break up with Timmy's mom, thereby getting his parents together.
Somewhat subverted in the Invader Zim episode "Bad, Bad Rubber Piggy" had Zim send a robot rubber piggy into Dib's past at crucial points to kill him, only he survives by an inch each time (though everytime he comes close to death he's given robotic body parts from his father due to losing his own) and after many mishaps, he sends a piggy to the past to warn him not to send any piggies to the past in the first place. Unfortunately the premise of the piggies was they replaced something in the timeline they're sent to and one replaces Zim's brain at the end.