History Main / RippleEffectProofMemory

* ''The Lazarus Project'' opens with main character Chris learning that he is one of a fractionally small percentage of the population with a natural immunity to the time-loop system used by the titular project to undo world-devastating events in history. Only a few other people in the project have a natural immunity, with others relying on regular medication to maintain their memories of each loop. The negative effects of this mutation are also presented; another future Lazarus employee jumped six months in mental development from the perspective of his parents before his first birthday (and obviously he was too young to realise what had happened) and his family misinterpreted his preserved memories as nightmares, only realising the truth when he was a teenager and was able to prevent his cousin destroying his family’s corner store as a failed insurance scam that killed the cousin’s family in the previous loop.

* Averted in ''VisualNovel/CrossChannel''. Taichi and Youko often figure out what's going on, but that is because there is one spot that doesn't reset at the end of every week. Records of past Taichis are kept here. [[spoiler:Miki at one point or another also discovered this and began hiding inside it every Sunday in order to avoid the resets.]] However, Nanaka DOES remember all the past weeks. But, as Taichi notices, she's not really 'there' and isn't exactly looping like the rest.

* Averted in ''VideoGame/CrossChannel''. Taichi and Youko often figure out what's going on, but that is because there is one spot that doesn't reset at the end of every week. Records of past Taichis are kept here. [[spoiler:Miki at one point or another also discovered this and began hiding inside it every Sunday in order to avoid the resets.]] However, Nanaka DOES remember all the past weeks. But, as Taichi notices, she's not really 'there' and isn't exactly looping like the rest.

* In ''Series/LegendOfTheSeeker'', [[AWizardDidIt Zedd]] tries to cast a spell to "de-program" Cara, but it backfires and results in a new timeline caused by Cara never becoming a Mord-Sith and, thus, not leading the Mord-Sith and [[BigBad Darken Rahl]] to Richard as he was performing the Boxes of Orden ritual. Richard and Kahlan were able to complete the ritual and make the known world [[MoreThanMindControl loyal to Richard]]. Richard becomes rules of [[TheEmpire D'Hara]] with Darken Rahl as his loyal advisor. Everything is great, as Zedd appears to be the only one who remembers the original timeline. Then it turns out that [[TheDevil the Keeper]] remembers it as well, and orchestrates to break the power of Orden. Luckily, Zedd is able to get a CloseEnoughTimeline by using the same spell on another Mord-Sith (thus, undoing the first casting).

* ''Series/{{Arrowverse}}'':

** In "[[Recap/RedDwarfSeasonVAngelsAndDemons Angels & Demons]]", Lister mentions having "played pool with planets" as a point of reference for the remarkability of his first taste of an edible pot noodle. However, according to Kryten's explanation at the end of "[[Recap/RedDwarfSeasonIVWhiteHole White Hole]]", he shouldn't have been able to remember that. [[RuleOfFunny But that's okay.]]

* Parker, the hero from ''Series/SevenDays'', was picked by Project Backstep for his high tolerance for pain and a photographic memory. He would be briefed on the event that needed to be changed and sent back to change it. Though neither he, nor other characters from the series have this ability. It ''did'' happen to a kid where the alien spacecraft went through a ''plane'', who could remember the past seven days. Parker on the other hand, if he's not the one piloting the machine, forgets like the rest of them. This was actually the plot point of one episode, where Parker is about to be sent back in time, when he spits out the awful tea Olga gives him on the controls, causing a short which kick-starts the Backstep with only his duffel bag in the Sphere. Amazingly, the Sphere ends up in the same place 7 days prior, but all they find inside is the bag with a key (an actual key). They have no idea what needs to be stopped, so Dr. Mentnor re-enlists the help of a psychic whom he used once to try to resolve a hostage situation (the failure drove the little girl to a mental hospital). After touching the key, she starts getting glimpses of the future 7 days. With her help, the crisis is averted, although she does warn Parker to lay off Olga's tea.

* In ''[[LightNovel/HaruhiSuzumiya The Disappearance of Suzumiya Haruhi]]'', when [[spoiler:Yuki reshapes the world,]] Kyon is the only one who remembers, because [[spoiler:Yuki wants him to have a ResetButton.]]

* While not necessarily related to TimeTravel, anyone with knowledge of the Crimson World in ''LightNovel/ShakuganNoShana'' can remember the existences of people or things that have lost their Power of Existence.

* Used in ''Series/MysteryScienceTheater3000'' episode 821 "Time Chasers". Crow, attempting to help Mike, goes back in time to keep him from getting stranded in space. When he returns, he learns that instead of Mike, he's partnered with his chain-smoking, beer-swilling Jerkass brother Eddie, who's whipped Servo into a quivering yes-man; only Crow remembers the original timeline, which he eventually restores.
** The funniest part is that Eddie doesn't doubt him at all. He just gets pissed that Crow thinks their timeline "sucks".

** In "A Stitch in Time", an already-unbalanced scientist uses her time machine to go back and execute notorious serial killers before they hurt anyone. Each time history changes, and she remembers each and every change, driving her crazier and crazier. In the end, [[spoiler: she (and a homicide detective following her murders) go back in time to save her younger self from the sexual assault which originally caused her problems. The scientist loses this (having essentially erased herself), but the detective gains it and realizes that her best friend was killed by one of the serial killers whom the scientist had no motivation to kill in the current timeline. The detective then starts killing serial killers...]]
** In "Déjà Vu", Dr. Mark Crest is able to remember previous iterations of the GroundhogDayLoop. Immediately before being struck by the expanding teleportation field, he grabbed a transformer cable and the electromagnetic field that it generated partially cancelled out the effects of the loop. In a later iteration, he brings his colleague Dr. Cleo Lazar [[NoPunIntended into the loop]] by holding her as he grabs the cable.

* Speaking of SaveScumming, this is a prominent gameplay feature of ''VideoGame/LifeIsStrange'':

** Max's powers later expand to include MentalTimeTravel into photos of herself, allowing her to alter events ''years'' in the past. After a minute or two in the confines of the photo, however, she returns to the altered present with no way of knowing how much has changed.

* At the end of ''Series/KamenRiderBuild'', [[spoiler: in order to defeat Evolt, the world is fused with a parallel world where the Sky Wall doesn't exist, undoing everything that Evolt did. However, nobody remembers any of their time in the old world, since you can't remember something that technically never happened. The only exceptions are Sento and the old world's Ryuga, who were both inside the rift between worlds when the merge happened and thus ended up being carried directly over to the new world. They even run into a version of Ryuga who was never born with Evolt's DNA, elsewhere there's a Takumi Katsuragi who was never memory wiped and applied with the likeness of Taro Satou (who as a result is still alive in this world) in order to become Sento.]]

* In ''Anime/SerialExperimentsLain'' episode 11, [[spoiler: Lain's child-like incarnation (I think)]] alters history to remove some rumors around school about Arisu but leaves Arisu's memory intact. After all, memory is just data. Arisu finds the whole experience a bit unnerving.

* [[spoiler: Hatou]] from ''Manga/MurasakiiroNoQualia'' can share memories, experience and knowledge with her selves from [[AlternateUniverse parallel worlds]].

* In the ''LightNovel/NyarukoCrawlingWithLove'' light novels, OrdinaryHighSchoolStudent Mahiro Yasaka has the extremely rare ability to perceive and be unaffected by shifts in the space-time continuum. This gets an off-hand mention in one of the first novels, but [[ChekhovsSkill comes back in a big way later]], when [[spoiler:Nyarko and Cuuko get RetGone by a bitter ex-classmate, and only Mahiro knows anything's changed, meaning he's the one who has to save the day.]] Considering how much author Manta Aisora loves referencing ''Series/KamenRider'', this may well be a ShoutOut to ''Series/KamenRiderDenO'' and its Singularity Points (see below).
* ''LightNovel/ACertainMagicalIndex'':
** Touma Kamijou's [[AntiMagic Imagine Breaker]] prevents him from being affected directly by alterations in reality, so his memories don't change when reality changes.
** The Will of the Misaka Network keeps her memories when reality changes as well. She claims it is because she exists in a state between life and death.
* Played with during the Class 3-4 arc in ''LightNovel/SundayWithoutGod''. Thanks to having left the sealed city, Alice and Dee are more aware of the GroundhogDayLoop Class 3-4 is trapped in than the other students are, but within the seal their memories are still not entirely reliable, [[spoiler:especially with Dee actively trying to prevent Alice and Ai from discovering the truth, and the seal only breaks when Alice is able to remember the entire truth about why his classmates wished to reset time.]]

* {{Justified|Trope}} by Chronos in the ''Literature/IncarnationsOfImmortality'' series. As the Incarnation of Time, him and his memory would be impervious to any ripple effects. (Within reason; he isn't allowed to affect the past in a way that would prevent him from becoming Chronos.)

* The time-traveling protagonist of Ward Moore's novel ''Literature/BringTheJubilee'' accidentally ends up changing the outcome of UsefulNotes/TheAmericanCivilWar from a Confederate victory to our own time-line. He remembers the previous history, but is stranded in our version of reality and lives of the rest of his life here.
* In Creator/RebeccaLickiss's ''Literature/EccentricCircles'', characters can remember what existed before it was rendered RetGone by the rifts.
* The Creator/DeanKoontz novel ''Literature/{{Lightning}}'' has a complicated example. [[spoiler: The traveler goes into the future and falls in love with a crippled woman. He then goes to her past (still his future) and prevents the crippling incident from happening; thus the later future that he visited no longer exists. He protects her in this way several times and eventually arrives at the timeline in which most of the book takes place, but he can still tell her about all of the other timelines that he visited.]]
* In ''Literature/{{Pact}}'', which is filled with creatures that toy with the memories of others, Isadora the RiddlingSphinx is proof against most memory manipulation, as remembering is part of what her kind was designed for. She can even stand against an effect that renders the person it hits an {{Unperson}}; though she'll usually lose a good amount of information about them personally, she retains enough to put the pieces together and describe their basic personality.
* In the ''Literature/YoungWizards'' series wizards can change the past ''without'' TimeTravel, by magically invoking a RealityBleed from an AlternateUniverse where the past worked out differently; only wizards will remember what the past used to be like. This is very useful for maintaining the {{masquerade}}. Unfortunately this means if the said thing involves a wizard dying, that specific part is irreversible.

* ''Franchise/DoctorWhoExpandedUniverse'':
** In the ''Literature/NewSeriesAdventures'' novel ''[[Recap/NewSeriesAdventuresEnginesofWar Engines of War]]'', when people are erased by the Daleks Temporal Weapons memories are retained but people can't put them together. However, the Doctor knows what has happened.
** In the ''Magazine/DoctorWhoMagazine'' short story "Brief Encounter: A Romantic Evening", the Brig and Doris have a partially ripple-proof memory; the more they look at their wedding photos and see that the Doctor was there, the more they remember that happening, but they ''also'' remember that they used to remember it differently.
** Similarly, in "Literature/ContinuityErrors", Andrea can sense that her backstory used to be different before the Doctor started mucking about with it.
* In ''Literature/ElevenTwentyTwoSixtyThree'', history can be altered using a time portal called the Rabbit Hole, but the time traveler will always remember history the way it was before. Additionally, the Rabbit Hole emits some sort of radiation which causes the memories of people near its openings to be fully or partially shielded from timeline changes.
* In ''Literature/TheEndOfEternity'', all the workers of the titular organisation are wearing a special device when they might get caught up in a reality change.
* At the end of Creator/IsaacAsimov's "Literature/GimmicksThree", a man travels to the past to the point where he signed a DealWithTheDevil. He himself has no memories outside of a vague uneasy feeling which caused him not to sign. However, demons are not affected by such things, so the one who tempted him is very upset... and so are his superiors going to be once he gets home.

* ''Literature/AllOurYesterdays'' averts this, as Em has no memory of her 14 past escape attempts besides a note written in her own hand.
* The White Queen in ''LightNovel/TheUnexploredSummonBloodSign'', due to being the strongest being in existence with power over (among many other things) time. When [[spoiler:Kyousuke]] travels back in time to prevent someone's death, she remembers it all [[spoiler:and congratulates him. The only other people to remember are Kyousuke and the person who was saved]].
* In one of the ''Literature/{{Griezelklas}}'' books by Creator/TaisTeng, Meral summons the trickster god Loki who proceeds to make her life a living hell. He shows up in her class one day to wreck havoc, having changed everyone's memory to think he has been a student from day one. Meral is the only person who actually knows the truth about Loki's true nature, but isn't able to prove it until he overplays his hand.

* In the ''Franchise/MagicTheGathering'' novel ''Literature/TimeStreams'', Urza sends Karn back in time to prevent a Phyrexian spy from leaking the Tolarian Academy's plans and killing everyone there. Karn remembers the events of the original timeline, while Urza, being a powerful planeswalker, remembers the broad strokes of said timeline despite not having travelled through time himself.

* In ''Fanfic/AlyaAndTheHaremReality'', Alya, in desperation to keep Monarch from using the Ladybug and Cat Miraculous to reset reality, grabs the Ladybug Miraculous from him and wishes that people love Marinette before he can make his wish (since Marinette already has HundredPercentAdorationRating and she thought such a wish wouldn't change the world that much), inadvertently making a new timeline where Alya and Chloe [[{{Polyamory}} are both Marinette's girlfriends]] and her teammates as active heroes. Alya, the Kwamis, and Gabriel all have a {{Downplayed|Trope}} version of this trope: they can vaguely recall things such as previous Akumas and Sentimonsters, a vague sense of the timeline and the names of Miraculous wielders from the old timeline and some personality traits or characteristics like Cat Noir's fondness for puns or competence, but not the identities of the heroesh. Alya also remembers certain facts she learned from other worlds, such as Chloe having an American half-sister named Zoe or Rose having an unidentified chronic illness.

* ''Series/QuantumLeap2022'', a continuation of the original show, implies that Ziggy itself has this as it has information on both original and post-leap timelines. An episode also shows a direct effect of a character in the show's "present" ''not'' having this, as they speak of a suddenly changed future as though they had always remembered it that way.

* ''Series/QuantumLeap2022', a continuation of the original show, implies that Ziggy itself has this as it has information on both original and post-leap timelines. An episode also shows a direct effect of a character in the show's "present" ''not'' having this, as they speak of a suddenly changed future as though they had always remembered it that way.

** Explicitly referenced in another book in the series, when [[SufficientlyAdvancedAlien the Drode]] first "restores" the Animorphs' memories in a way that lets them still remember the last five or so minutes of conversation but ''not'' any other details about the CrapsackWorld in which they now live, then mentions that their memories will be "buffered" as they follow Visser Four through history. The Time Matrix also seems to confer this ability on to everyone who uses it (at least for changes they make using the Time Matrix), including Visser Four himself.
** Cassie is shown in Megamorphs #4 to be a temporal anomaly who has this ability by default--if her timeline is altered, she gradually becomes aware of the discrepancy and subconsciously causes the alternate timeline to fall apart.

* Okabe from ''VisualNovel/SteinsGate'' has one of these. [[spoiler: John Titor wants him to use it to become the Messiah and overthrow the coming new world order.]] He calls it “Reading Steiner” which doesn't really mean anything but sounds pretty cool.
** Played more plausible than most examples since he usually gains no more than a weeks worth of memory at a time and it still disorients him immensely to the point of IdiotBall (from the point of view of other characters who don't have this ability).
** Also, not only is Okabe the only person with this effect, but he has no idea how he got it or ''why'', though it's implied it was due to a childhood illness. Many of his problems from the first half of the series are caused by not being able/willing to see the world changed, which coupled with the social skills of a turnip results in him scaring or temporarily vilifying most of the main cast. Then the KnightOfCerebus [[FromBadToWorse shows up ...]]
*** The series later explains that the ability for people to retain memories of alternate timelines is not something exclusive to Okabe. Rather, his Reading Steiner ability is just an extremely advanced form in comparison to everyone else. By bringing others to key location-points in their lives from alternate timelines, he is able to eventually trigger their memories of them.
** TheMovie explains this more and thoroughly {{deconstruct|ion}}s it. Turns out all humans have his ability, it's just far, far weaker. It's called "déjà vu." And Okabe's ability to recall different timelines slowly starts to become a case of BlessedWithSuck as the knowledge of so many alternate worlds is beginning to cause some mental breakdowns...

* Naturally, the ''Franchise/BackToTheFuture'' trilogy. It is a bit strange though, that while ''memory'' is proof against the ripple effect, ontology is ''not'': Marty remembers his own timeline in the [[Film/BackToTheFuture first movie]], and yet he comes close to ''fading out of existence'' as history is pushed off-track. It may be that in ''BTTF'', memory is not proof against the ripple effect ''per se'', just a bit insulated from it, and like Marty's photograph, will [[DelayedRippleEffect fade slowly as the timeline diverges]]. Or it's just a big TimeyWimeyBall.
** Marty almost fades away in the first film because he almost changes the timeline to one where his parents never got together and thus he was never born. The timeline he ends up creating by the end of the movie is one where his parents DID meet but under different circumstances and thus he WAS born, but his new alt-timeline dad has an intestinal fortitude he never had originally, and his whole family is better off for it. If memory and ontology were both immune to the ripple effect, then what would be left to change as a result of time travel?
** The lack of an alternate version of Marty is averted in the second movie, however. It is implied that there is an alternate version of Marty in the new timeline, but Marty never meets him because Biff sent him OffToBoardingSchool. If that Marty really existed, it'd mean Marty would meet an alternate self in every reality he created.
*** One of the [[ComicBook/BackToTheFuture comics]] has Doc visiting this timeline's version of himself, lobotomised in a mental home. Doc believes that if they didn't act fast to put the timeline right, a DelayedRippleEffect would wipe himself, time travelling Marty and the [=DeLorean=] from existence.
** In the novelization of ''Film/BackToTheFuturePartIII'', it's also implied to work in the other way. Marty gets help from 1955 Doc to go back to 1885 and save the 1985 Doc. When he gets there, 1985 Doc asks him not only how he got there, but also who dressed him in such ridiculous clothes. Marty says that 1955 Doc did. At which point Doc remembers. That could just as easily be explained as Doc not really remembering (to him) a 30-year-old minor event until Marty reminded him.

** ''Film/XMenDaysOfFuturePast'':
*** Wolverine is told up-front that he (and only he) will remember the BadFuture should he succeed in changing history. [[spoiler: In the end, he wakes up in the "good future" with his memories diverging from real history since it was changed in 1973.]]
*** Professor X does have some memories of the original time line since his younger version linked to the original time line version through Logan. After Logan sees all the reset changes, Xavier tells him "they have a lot to talk about."

* In the Wiki/SCPFoundation universe, DependingOnTheWriter the Foundation might have an archive whose data is immune to alterations due to a changed past. The Foundation can compare current reality to the contents of the archive to determine if anything has been mucking around with the past.

When TimeTravel is used to "rewrite" past events, this character will retain their memory of the original timeline—i.e., how everything went the "first time around"—even though that version of events [[TimeTravelTenseTrouble no longer will have happened]]. Everyone else will only remember the new reality. This is a NecessaryWeasel for time travel stories; how can someone SetRightWhatOnceWentWrong if they don't know that something went wrong in the first place?

* In the ''Franchise/PowerRangers'' crossover "[[https://www.fanfiction.net/s/13550638/1/Forever-Yellow Forever Yellow]]", events lead to Summer Lansdown (''Series/PowerRangersRPM'') travelling to the "prime" Ranger universe by accident, subsequently forming an alliance with various other Yellow Rangers to prevent a version of Venjix being created in this reality. At one point the "natvie" Venjix manages to create a future where it has become a vast computer system controlling the whole world, to the extent that SPD and Time Force are sent back to stop the assembled Yellows from destroying it, but since Katie and Z had already been brought back before history was changed they are able to confirm to their teammates that history has been altered.

* At the climax to ''Machinima/RedVsBlue'''s Blood Gulch Chronicles, [[spoiler:Wyoming's time-resetting power resets his foes' memory, with the exception of Tucker, whose alien sword prevents the effect and lets him and Church beat Wyoming.]]

* At the end of ''Series/KamenRiderBuild'', [[spoiler: in order to defeat Evolt, the world is fused with a parallel world where the Sky Wall doesn't exist, undoing everything that Evolt did. However, nobody remembers any of their time in the old world, since you can't remember something that technically never happened. The only exceptions are Sento and the old world's Ryuga, who were both inside the rift between worlds when the merge happened and thus ended up being carried directly over to the new world. They even run into a version of Ryuga who was never born with Evolt's DNA.]]