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->'''Teddy:''' Lenny, you can't trust a man's life to your little notes and pictures.\\
'''Leonard:''' Why not?\\
'''Teddy:''' Because your notes could be unreliable.
-->-- ''Film/{{Memento}}''

Alice has some agenda that leads her to tell a falsehood to Bob, such as introducing herself as a person named Claire. Alas, an [[TapOnTheHead unfortunate accident]] later, Alice gets EasyAmnesia! (Un)Fortunately Bob is present to tell her all she needs to know: as far as he knows she is really Claire, and having forgotten her real identity, she actually believes it. Depending on the tone of the work, [[PlayedForLaughs hilarity]] and/or [[AmnesiaDanger drama]] will ensue.

May also be used in a MemoryGambit by a {{Chessmaster}} to conceal their own AmnesiacDissonance more fully, and make their lie convincing - because now, everyone involved has ''no reason to disbelieve it''.

Compare AmnesiacCostumeIdentity, where Alice gets amnesia while wearing clothes that are not her own, with similar results, and CriminalAmnesiac, where Alice's amnesia causes her to believe Bob the villain when he says that she is on his side.

This trope is often used to hide a DarkSecret, TomatoInTheMirror or other PlotTwist. Beware of spoilers.

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!!Examples:

[[foldercontrol]]

[[folder:Anime and Manga]]
* In ''Manga/DeathNote'', both Light and Misa lose their memories as a result of Light's MemoryGambit. Unfortunately, this also leaves Light with no idea as to why he's Misa's boyfriend, leading to severe awkwardness when L quizzes them on their feelings for each other.
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[[folder:Comic Books]]
* One ''ComicBook/SupermansGirlFriendLoisLane'' issue has Lois get into a car accident while in disguise and become convinced that she is the person she's disguised as. In an ironic twist, she winds up hating Superman and Lois Lane, while also falling in love with Clark Kent.
[[/folder]]

[[folder:Fan Works]]
* ''Fanfic/EncryptWithinTheDarkToSaveTheClockworkOfAHeart'' begins with Yusaku discovering that Ai no longer has access to his memories. As Ai had previously ''pretended'' to have been an amnesiac liar, Yusaku isn't convinced until Pandor scans Ai's biometrics, confirming that he's legitimately unable to recall anything this time.
* ''Fanfic/{{Foxfire|RaharMoonfire}}'' has Prince Zuko lose his memories, leaving him convinced that he's a simple refugee named Li.
* ''Fanfic/{{Fragments}}'': Thanks to losing his memory, Sky doesn't realize that [[spoiler:he's actually a ''changeling'', not a pegasus]].
* In ''Series/TheRookie'' fanfic ''[[https://archiveofourown.org/works/35655838/chapters/88900207 House in Disorder]]'' Lucy suffers a blow to the head while undercover with a gang, and comes to genuinely believe she is her undercover persona as a result.
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[[folder:Film - Live-Action]]
* Inverted in ''Film/TheAddamsFamily'', where [[spoiler:the man impersonating uncle Fester turns out to be the real deal]], amnesiac.
* In ''Killerman'', Creator/LiamHemsworth's character Moe is an undercover cop who was posing as a money launderer but loses his memory in a car crash early on in the film and thus has no idea he was undercover. It eventually overlaps with CriminalAmnesiac because Skunk, his partner in money laundering, learns Moe's true identity by the climax but doesn't tell him. The film ends with them fleeing NYC together and Moe still under the impression that he's actually a gangster.
* In ''Film/TheLongKissGoodnight'', Samantha is really [[spoiler:a secret agent/spy]]. Because of her job, she had to lie about [[spoiler:being together with a guy who was actually a mark]]; when she lost her memory, she apparently [[spoiler:retained enough memory to believe that her last cover identity was her real name]]. She almost gets killed, instead being caught and tortured ([[spoiler:and her old mentor gets killed because of this]]), but [[spoiler:this torture allows her to regain her old memories and skills]].
* ''Film/{{Memento}}'': As quoted above, Leonard, who has anterograde amnesia, relies on a system of notes and photos, which Teddy warns him could be unreliable. [[spoiler:Turns out Teddy was right, and among other things, Leonard tricks himself into killing Teddy even though he's not the one Leonard is looking for.]]
* In ''Film/TrapForCinderella'', Micky is told that her friend Domenica died in the same fire that disfigured Micky. [[spoiler: Julia claims that she conspired with Domenica to kill Micky and have Domenica's face rebuilt to look like Micky's. Ultimately, it seems Micky was the one who survived the accident, then had her face reconstructed]].
* In ''Film/Unknown2006'', several of the amnesiacs remember being part of the kidnapping. [[spoiler:Jean Jacket]] find that the kidnappers outside recognize his voice...
* The {{similarly named|works}} ''Film/Unknown2011'' combines this with BecomingTheMask. [[spoiler: The film follows a character who's travelling with his wife, takes a cab and gets into a crash and wakes up in the hospital. When he makes his way back to the hotel, his wife is there, with a guy who claims to be him. Both his wife and the new husband swear they've never seen him before, and he has a full set of identification proving who he is. It turns out that he and his "wife" were assassins on a mission, and the crash apparently gave him amnesia, but he somehow remembered his cover identity and thought it was real. His employers sent in a replacement when his disappeared, using the same cover. When he learns all this, he decides [[AmnesiacDissonance he prefers the identity he woke up with]], and helps to foil the assassination plot.]]
* Inverted in ''Film/WhileYouWereSleeping'': When Peter wakes up from his coma, the rest of his family tells him that he's engaged to Lucy, but Peter doesn't remember her at all. So the family concludes he must have LaserGuidedAmnesia. [[note]]They aren't engaged, but Lucy had accidentally convinced his family that they were, and things escalated to the point where she couldn't set the record straight without making everything even more awkward.[[/note]] Peter becomes skeptical of the amnesia explanation as he realizes that he still remembers everything else about his life--but he gives up and goes along with his family anyway.
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[[folder:Literature]]
* [[spoiler:Sherlock Holmes]] manages to do it to himself in Creator/MichaelKurland's [[Literature/TheInfernalDevice Professor Moriarty novel]] ''The Empress of India''. [[spoiler:He has a secret identity as a criminal, as a way of keeping an eye on the criminal underworld. When he suffers a TapOnTheHead and wakes up in this lair, he deduces that this is his true identity, and proceeds to become a successful criminal.]]
* In ''Literature/HarryPotterAndTheChamberOfSecrets'', [[spoiler:Gilderoy Lockhart]] is a fraud who fabricated his entire career, but he successfully managed to keep the truth from getting out by generous use of memory charms on the people who ''actually'' did heroic things. When he unwisely attempts to cast another memory charm with Ron's broken wand, it malfunctions and backfires on him, giving him permanent amnesia and likely some brain damage. In the hospital he came to legitimately believe that the events in his career were true, since there was no one who knew the truth to explain to him otherwise.
[[/folder]]

[[folder:Live-Action TV]]
* In ''Series/DarkMatter2015'', none of the main characters can remember their original lives beyond what their Galactic Authority 'most wanted' profiles in the ship's database tell them and [[YouAreNumberSix go by numbers based on order of awakening from stasis]]. Crewmember One is surprised to be captured and interrogated by Jace Corso in "Episode 4" because that's who he thought he was; the encounter leaves him with no idea who he actually is or why he pretended to be a notorious criminal he's [[ActingForTwo somehow identical to]] (other than Corso having an [[BuffySpeak eviler]] aesthetic) or why he was on the crew of the ''Raza''.
** "Episode 8" reveals the truth after the ExpendableClone made from One's genetic profile (Transfer Transit is a common way to travel via BrainUploading to a temporary clone body in the setting) has a different face from his usual one. [[spoiler:He was a wealthy industrialist named Derrick Moss whose wife Catherine was killed in a breaking & entering, and One's current shipmate Marcus Boone (Three) was the prime suspect. One concludes that he copied Corso's appearance through SurgicalImpersonation to get close to and kill Three. Both One and Corso are played by Creator/MarcBendavid, while Moss is played by Creator/DanJeannotte]].
** Similarly, [[spoiler:Six is unaware at first that he was an undercover cop named Kal Varrick infiltrating the ''Raza'' for the Galactic Authority, not actually a criminal like the rest of the crew (''sans'' TagalogKid Five), although in his case "Griffin Jones" was an alias fabricated for his cover and not a separate person running around]].
* One episode of ''Series/{{Insecurity}}'' had [=JoJo=] develop amnesia after getting hit by Alex's car while undercover as a drug dealer's girlfriend, and said dealer convinces her that she ''is'' said girlfriend.
* Happens in at least one ''Series/MissionImpossible'' episode. In the new series, Shannon almost ends up marrying the villain's son.
* In one episode of ''PSI Luv U'', tomboyish LovableRogue Wanda suffers a blow to the head and is left amnesiac, believing her cover identity as a dutiful housewife is true.
* ''Series/SamanthaWho'' practically has this trope as part of its premise, as the protagonist has trouble finding out what was actually true about her pre-amnesia life.
* A minor example in ''Series/{{Smallville}}'': during the period that Clark didn't know Chloe knew he had powers, he developed amnesia when a meteor freak accidentally erased Clark's entire memory rather than just the last few hours. Chloe talked him through his powers and told him he used them for good, but since she didn't know his origin, she assumed he was a meteor freak.
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[[folder:Video Games]]
* In ''VideoGame/FinalFantasyVII'', the protagonist Cloud Strife narrates his past to the audience and the other characters at various points throughout the game. However, it turns out that [[spoiler:he in fact lost his own identity and was simply narrating the past of his dead friend Zack, some of whose memories he had absorbed through Jenova cells, deluding himself into believing that was his own identity]].
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[[folder:Webcomics]]
* The webcomic ''Webcomic/{{Picatrix}}'' has an example with a guy who believes himself ''on honeymoon'' with the heroine. Naturally, this doesn't end well for him when he makes advances on his "wife"...
** Then it's inverted, and more [[PlayedForLaughs hilarity ensues]].
[[/folder]]

[[folder:Western Animation]]
* The ''WesternAnimation/BatmanTheAnimatedSeries'' episode "[[Recap/BatmanTheAnimatedSeriesE8TheForgotten The Forgotten]]" has this happen to an undercover Bruce Wayne disguised as a homeless guy. He gets kidnapped by a [[FatSweatySouthernerInAWhiteSuit greasy, overfed slavedriver]] who runs a mining operation, while Alfred is trying to find him. Very poignant episode, as Bruce gradually uncovers his memories and retakes his [[TookALevelInBadass levels in badass]].
* Another Batman example happens in the ''WesternAnimation/BatmanTheBraveAndTheBold'' episode "The Mask of Matches Malone": a hit on the head causes the hero to believe himself to be Malone, his undercover gangster identity.
[[/folder]]

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