History Main / SplitPersonalityMerge

* ''Franchise/{{Gundam}}''

* ''Manga/SoulHunter'' has this with Taikoubou and [[spoiler:Ou Eki]]. They later [[spoiler:merge together to become Fukki]], although [[spoiler:Taikoubou is the main, dominating personality]].

This has been the accepted method of treatment of those with Dissociative Identity Disorder (DID) by psychiatrists until recently. Various media based on supposed real life accounts have often taken this route as well. However, more recently this method has become somewhat contested and some self-described "multiples" and psychologists believe that integration of split personalities isn't as helpful as once thought or could even be harmful.

* Fluttershy and Erica eventually perform this in ''FanFic/BecomingPonies''. As do one half of Twilight and Isaac.
* ''Fanfic/ChildOfTheStorm'' has Bucky with three separate personalities: Bucky Barnes, Steve's LovableRogue BestFriend and FriendlySniper; the Winter Soldier, the Red Room's implacable, hyper-efficient, and utterly ruthless SuperSoldier assassin; and James, who developed from the remnants of the former mixing with the latter. The first and last merge at the end of ''Child of the Storm'', with the Winter Soldier persona remaining as a SuperPoweredEvilSide that Bucky can unleash at will.
** In the sequel, [[spoiler: the Red Son persona]] merges with Harry - though as only a few months worth of memories, without much of a mind of his own, it's dubious whether this totally qualifies. It doesn't change Harry's personality much, but it does make him a much more dangerous opponent, as [[spoiler: the Red Son]] was programmed with all sorts of combat skills.
* In ''Fanfic/{{Flinch}}'', Sheik is the embodiment of all of Zelda's repressed anger and violent desires. She's a PsychoForHire while Zelda is an ActualPacifist. Eventually, Zelda comes to terms with her aggression, merges Sheik, and [[spoiler:gives Samus a NoHoldsBarredBeatDown]].
* Occurs to [[WesternAnimation/MyLittlePonyFriendshipIsMagic Twilight Sparkle]] near the latter end of ''FanFic/TheImmortalGame''. Earlier in the story, the psychological trauma of being transformed into [[SuperpoweredEvilSide Nihilus]] had caused her mind to {{split|Personality}} in two -- the dominant, [[ActualPacifist peaceful-to-a-fault]] Sparkle, and the more brutish Twilight. The two personalities spend quite some time [[TalkingToThemself arguing]], with Twilight pushing for a merge to restore themself to a full and equal mind, but Sparkle being too afraid that Twilight will pull a SplitPersonalityTakeover and be as [[HeWhoFightsMonsters monstrous as Nihilus was]]. Eventually, [[spoiler:[[BigBad Titan]] captures Sparkle and tortures her. The pain and desperation causes Sparkle to accept Twilight and fuse back with her, recreating the ''real'' Twilight Sparkle]]. Cue [[HesBack asskicking]].
* ''Fanfic/PonyPOVSeries''

* ''FanFic/AShadowOfTheTitans'': According to [[EnemyWithin the Queen]], the longer that Jade spends in Shadowkhan form, the more this process will occur with the two of them, until eventually all that's left will be a being with the Queen's amorality, but with Jade's wit to keep her from being StupidEvil.
* [[http://www.tthfanfic.org/Story-11037/Mediancat+The+Sum+of+Their+Parts.htm The Sum of Their Parts]] is a fanfic that begins by establishing that Faith (from Series/BuffyTheVampireSlayer) [[http://www.tthfanfic.org/Story-10602/Mediancat+April+10+1997.htm is actually an alternate personality]] for WesternAnimation/{{Daria}} Morgendoffer produced to handle her rage over [[spoiler:her family's brutal murder]]. Eventually she winds up in a fight with [[spoiler:Glorificus who steals the mental energy maintaining their separation]]. Then [[spoiler:Willow pulls the same trick on Glory/Ben]]. [[spoiler:Daria's and Faith's minds work together to become "reason, backed by intuition... more than the sum of her parts," while Glory/Ben become completely paralysed by indecision: "less than the sum".]]
* In "Two For One" of the ''WesternAnimation/DannyPhantom'' ''FanFic/FacingTheFutureSeries'', [[spoiler:at the end of the BattleInTheCenterOfTheMind where his ghost half wanted to do a SplitPersonalityTakeover, Danny managed to convince him that they were two sides of the same coin and that they needed each other, while apologizing for always seeing him as a burden. This resulted in his two halves merging and Danny getting control of his powerful [[SuperMode True Ghost Form]].]]
* In ''Fanfic/TheWeaverOption'' the intense Callidus indoctrination and brainwashing apparently broke the mind of [[spoiler:Sophia Hess]], replacing her with the loyal apprentice Elena Kerrigan. However, on learning about Taylor's success, [[spoiler:Sophia]] resurfaced due to the sheer ''rage'' she felt. Elena's mind fought back but could not kill the original as that would destroy their soul; [[spoiler:the Emperor]] instead forced the two minds to merge into a single individual.

** In the penultimate episode of Season 5, the barriers separating Glory from her [[SealedInsideAPersonShapedCan human vessel]], Ben, begin to break down. While they still inhabit Ben's body separately, their memories and personalities begin to merge together. This leads to Glory manifesting Ben's empathy and humanity, and Ben inheriting Glory's [[ItsAllAboutMe selfishness and ruthlessness]].

* ''Series/KamenRiderBuild'': The original identity of [[spoiler: Takumi Katsuragi]] resurfaces after [[ItMakesSenseInContext some demonic possesion shenanigans]] knocked out his SplitPersonality, but opts to merge with him after becoming convinced that its the better solution, resulting in the latter's identity getting most of former's memories. He still hangs out in [[spoiler: Sento's]] mind to observe him afterwards and occassionally comes forth to talk to him in their shared mindspace.

* Season 3 of ''Series/StarTrekPicard'' has a downplayed example: Data and Lore's minds are essentially restored and put into a single positronic mind. When a BattleInTheCenterOfTheMind ensues for control over the shared body, Lore seemingly subsumes Data for a complete SplitPersonalityTakeover -- but because Lore deliberately assimilated Data's memories as trophies of his conquest, he effectively becomes Data but with some of Lore's personality (fortunately, not the malevolent aspects) mixed in.

** Piccolo and Kami, who had become a LiteralSplitPersonality decades earlier. (With a little {{reincarnation}} in-between. [[Manga/DragonBall It's complicated.]]) Not to be confused with the time [[FusionDance Piccolo fused with Nail]], a completely different and unrelated ([[IdenticalStranger though identical-looking]]) Namekian.

* ''Fanfic/ShadowsOverMeridian'': Part of the backstory for this story is that Jade and her EnemyWithin, the Queen of the Shadowkhan, eventually decided they needed each other to survive, so merged together to form a new personality with aspects of both. The main side effect of this is Jade gaining total control over the Shadowkhan tribes.

* ''Manga/{{Change 123}}'' is all about trying to merge the personalities of Motoko and [=HiFuMi=] [[spoiler:and Zero]].
* Done uniquely in ''Anime/DanganRonpa3''. [[spoiler:One of the main characters, Hajime, underwent a surgery that replaced his personality with a different one, which was then renamed Izuru. After [[VisualNovel/Danganronpa2GoodbyeDespair the events of the second game]], the two of them managed to reach an accord and merge, signified by heterochromia--one eye Hajime's green, the other Izuru's red. However, rather than one of them being dominant, the resulting persona has traits from them ''both'', and upon being asked which name he goes by in the OVA simply says "either is fine".]]

The resulting merged personality is usually a composite of the parts that is well and truly psychologically stable. This is especially true if they were an [[TheMcCoy id]], [[TheKirk ego]], and [[TheSpock super ego]]. If they were [[GoodAngelBadAngel moral]] or [[RedOniBlueOni temperamental]] opposites, the resulting merged personality will keep traits of both. In more action-driven works, this merger includes combat ability and powers, so if the character had a [[CrouchingMoronHiddenBadass moron and a badass]] coexisting, the united whole will be a badass all the time... while occasionally tripping on banana peels. Similarly, if the reason for the personality split was to seal awesome cosmic powers away (resulting in a SuperPoweredEvilSide; see both EnemyWithin and EnemyWithout) the united self will have full control over these powers without risk of SuperPowerMeltdown or corruption.

* Sownplayed and reconstructed in ''Literature/TheWheelOfTime'': Rand Al'Thor suffered a long time clashing with his previous incarnation, psychotic and homicidal Lews Therin Telamon, and finally snapped. Eventually he [[spoiler: realized, that "voice of Lews Therin" was a way to manifest his memories and experience from previous life, and accept them as his own. Afterwards, he is still Rand, but much more stable, wiser and knowledgeable]].

* ''Literature/TheWheelOfTime'': Rand Al'Thor suffered a long time clashing ever more obviously with the voice in his head (which could take over his body at times), that of his previous incarnation, Lews Therin Telamon, and finally snapped in a long overdo psychotic break. Eventually he [[spoiler: becomes insanely homicidal and then nihilistic, raving about destroying all humanity as everything is pointless. He and his previous incarnation (which as he seemed to be able to take over Rand's body and control of Saidin can be seen as a split personality) reach a kind of epiphany and he manages to step back from the brink. Afterwards the narration makes clear he will never again hear the voice of Lews Therin again, likely because he at last accepted the simple truth, 'that they were not two people, and never had been']].

* The goal of the Meta (a gestalt entity of AIs created as [[LiteralSplitPersonality Literal Split Personalities]]) in ''Machinima/RedVsBlue: Reconstruction'' is to reconstruct the original Alpha [=AI=] from which they were split off. According to WordOfGod, the first AI in the Meta (Sigma) intended to rebuild the Alpha with itself as the leader.

Minus the superpowers, this is the RealLife scenario that until very recently was believed to be the best solution by doctors working with multiples clear back to [[https://books.google.com/books?id=oDlq6EtyR8wC&dq=%22My+life+as+a+dissociated+personality%22&printsec=frontcover&source=bl&ots=jG6Ha_RbAf&sig=Y_R015UyfFOxrGfDhIjzPb3V9sA&hl=en&ei=bA34SYyBM6b4tAO336nsDg&sa=X&oi=book_result&ct=result&resnum=1#v=onepage&q=%22My%20life%20as%20a%20dissociated%20personality%22&f=false Dr. Morton Prince in the early 1900s]]; many books on multiple personality disorder follow this storyline of helping patients integrate their numerous identities to achieve mental health. The many books on MPD/DID written by professional psychologists and published in the '80s and '90s [[note]]not official, psychiatric case studies but popular accounts, novels really, which purported to be based on (sometimes [[VeryLooselyBasedOnATrueStory very loosely]]) these doctors' work with abuse survivors who might have been multiple.[[/note]] tend to end with Integration as a HappyEnding, either Disneyesque [[note]]As multiples began speaking up for themselves in the late '80s-early '90s, rather than letting mental health professionals have full control of the narrative, some observed that many doctors, and numerous books on the subject, seemed to equate "integrated" with "[[{{Housewife}} June Cleaver]]."[[/note]] or a spiritual experience akin to a conversion. Actual multiples report YMMV on this experience; while merging has indeed been helpful for some,[[note]]Chris Costner-Sizemore, the real ''Film/TheThreeFacesOfEve'' integrated permanently and really did feel it was the answer[[/note]] others who have gone through it have ''deliberately'' de-integrated themselves later on, feeling that the whole is ''less'' than the sum of the parts.[[note]]Sybil and Billy Milligan, arguably the two most famous cases of the 1970s, both ended up de-integrating and felt much better for it.[[/note]] Still others can integrate and separate at will, but report it as an unpleasant experience. ''Literature/WhenRabbitHowls'' is a notable autobiography covering that side of the subject, written by members of a multiple collective who spoke out vehemently against this idea as a form of murder. To multiples who feel this way, it's better to learn how to communicate and work together as a SplitPersonalityTeam or MindHive. Psychology professionals have come to accept this viewpoint in recent years as well, believing that having these people learn to safely coexist is just valid as attempting to merge them.

* In ''Film/AvengersEndgame'', [[spoiler:we see that in the five-year TimeSkip after the Snap, [[ComicBook/IncredibleHulk Bruce Banner and the Hulk]] have reached an accord and accepted each other as part of the same being, so there is no longer a transition between the two. "Professor Hulk" retains the Hulk's size, strength and skin tone, but with Banner's brains and easygoing personality (and his wardrobe, [[NerdGlasses glasses]] and [[VocalDissonance gentle voice]]).]]

* ''ComicBook/IncredibleHulk'': Doc Samson once pretended to have done this to the Hulk and Bruce Banner, via EpiphanyTherapy. But [[FailureIsTheOnlyOption eventually the change in premise became too much of a problem for the Hulk's title]], and the writers made use of the fact that Therapy Does Not Work That Way to establish that Samson had really just created a new, if more stable, alternate. [[CanonDiscontinuity Tossing out the fact that Doc Samson wasn't really in control of the process and didn't fully understand what was happening at the time.]] Since there are three "main" Hulk personalities (Savage Hulk, Child Hulk and Gray Hulk) and several secondary ones like Devil Hulk and the aforementioned Professor Hulk, it's a topic they have explored several times since, sometimes without including Banner in the merger at all.

** The Buu Saga liked to play with this. For starters, the FusionDance merges two fighters' personalities as well as their appearances. After that, Majin Buu is absorbed by his [[EnemyWithout dark side]], but the new hybrid form is restrained from killing some people due to his good side's influence... ''[[KillEmAll Some]]'' [[KillEmAll people]].

* ComicBook/GreenGoblin:
** The Goblin has undergone this after his 1996 comeback, the Goblin previously veering between being an outright SplitPersonality of ComicBook/NormanOsborn, a psychotic break from reality and the power fantasy of an unstable CorruptCorporateExecutive who just won the SuperpowerLottery. Naturally, the amalgation of a mentally ill white collar criminal with his homicidal maniac alternate persona did not exactly make things better- the new Norman Osborn was a MagnificentBastard who developed particularly twisted views on his emnity with Franchise/SpiderMan and graduated from millionaire industrialist to head of S.H.I.E.L.D. (because HumansAreMorons). Recently, the Goblin has shown signs of making a comeback, in the form of delusions and homicidal mania.

* ''Franchise/GreenLantern'': After transforming into Star Sapphire during the mid-80's due to not being able to cope with the extended absence of Hal Jordan, Carol Ferris split into two beings — Predator, which represented "the male side of her", and Carol herself, who was the normal "female side" that loved Hal. After Hal Jordan decided to quit the Green Lantern Corps, Predator kidnapped Carol Ferris and performed a Fusion Dance with her that changed them into Star Sapphire right before Hal's eyes. Later, though, Carol grew more stronger when she accepted the Star Sapphire ring willingly to the point that she regained control of herself in her Star Sapphire form.

* ''Franchise/{{Superman}}'':
** In ''ComicBook/AdventureComics'' #313, an evil ComicBook/{{Supergirl}} is created when Kara gets exposed to red Kryptonite. At the end, though, Satan Girl is reabsorbed back into Kara.
** In ''[[ComicBook/Supergirl2005 "Girl Power"]]'', ComicBook/LexLuthor used a piece of black Kryptonite to create an evil Supergirl clone, and Franchise/WonderWoman used her Lasso of Truth to merge both Karas back into a single being.

* ''WesternAnimation/TeenTitans'': In "Nevermore", Cyborg and Beast Boy accidentally enter Raven's mindscape, where the personifications of all her emotions live (i.e. Pink Raven is her happiness, Gray Raven is her shyness). When Trigon appears to menace her friends, the Ravens come together to defeat him.

-->'''Raz''': Are you... the real Cassie O'Pia?
-->'''Cassie''': I'm not sure. But I'm sure she's in here somewhere.

-->''Raz''': Are you... the real Cassie O'Pia?

* ''ComicBook/IncredibleHulk'': Doc Samson once pretended to have done this to the Hulk and Bruce Banner, via EpiphanyTherapy. But [[FailureIsTheOnlyOption eventually the change in premise became too much of a problem for the Hulk's title]], and the writers made use of the fact that Therapy Does Not Work That Way to establish that Samson had really just created a new, if more stable, alternate. [[CanonDiscontinuity Tossing out the fact that Doc Samson wasn't really in control of the process and didn't fully understand what was happening at the time.]] Since there are three "main" Hulk personalities (Savage Hulk, Child Hulk and Gray Hulk) and several secondary ones like Devil Hulk, and the aforementioned Professor Hulk, it's a topic they have explored several times since, sometimes without including Banner in the merger at all.

* ''ComicBook/IncredibleHulk'': Doc Samson once pretended to have done this to the Hulk and Bruce Banner, via EpiphanyTherapy. But [[FailureIsTheOnlyOption eventually the change in premise became too much of a problem for the Hulk's title]], and the writers made use of the fact that Therapy Does Not Work That Way to establish that Samson had really just created a new, if more stable, alternate. [[CanonDiscontinuity Tossing out the fact that Doc Samson wasn't really in control of the process and didn't fully understand what was happening at the time.]]

** ''ComicBook/SupermanReborn'' reveals [[spoiler:the creation of the ''ComicBook/New52'' continuity caused Superman to be [[LiteralSplitPersonality separated]] into his pre-''ComicBook/{{Flashpoint}}'' and ''[=N52=]'' selves, explaining why were there two versions of Superman flying around at the end of the ''New 52'', when no other character displayed such problem. At the end of the story, they merge into a single, complete version of Superman.]]

* At the end of season 2 of ''Series/CloakAndDagger2018'', it's ambiguous whether this has happened to Bridget and Meyhem, or whether Meyhem's still in control but ''listening'' to Bridget in her head.