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The Mind Is a Plaything of the Body

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"The awakened, the enlightened man says: I am body entirely, and nothing beside; and soul is only a word for something in the body. Your body is a great intelligence... your little intelligence, brother, which you call "spirit", is also an instrument of your body, a little instrument and toy of your great intelligence."note 

Maybe it's just the animal instincts associated with your new form, a change in hormones or the complete rewiring of your neural circuitry, but for some reason the process of shapeshifting tends to also transform the very way you perceive and think about the world around you.

This may be relatively minor (e.g., you notice smells more and food seems more exciting) or may be so extreme that you're not even recognizable as the same person any more. The latter is particularly tragic when a more drastic change is combined with a permanent transformation, as it can be seen as a form of death. It is also sometimes used to bless a voluntary shapeshifter with suck. The classic Wolf Man fits this trope perfectly: a normal human most of the month but a rabid wolf/wolfman under a full moon.

The title of this trope is a paraphrase of Friedrich Nietzsche's declaration that the mind and soul are completely illusory products of one's physical brain and body (page quote).


Often part and parcel of the Superpowered Evil Side and Transhuman Treachery. See Sense Freak for a much milder example, and Loss of Identity for the much more extreme end result. Cybernetics Eat Your Soul is a subtrope. Can lead to Immortal Immaturity and the Second or Third Law of Gender-Bending — in fact, this tends to be especially common in magical Gender Bender fiction.

Compare Becoming the Mask, Shapeshifter Mode Lock and And I Must Scream; contrast Different for Girls. May lead to/from Sense Loss Sadness. Often overlaps with Furry Reminder and/or My Instincts Are Showing.

For the exact opposite effect, where the body is a plaything of the mind, see Your Mind Makes It Real and some forms of Empathic Shapeshifter.



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    Anime & Manga 
  • Ayakashi Triangle:
    • After being turned into a girl, Matsuri's overall personality remains mostly masculine, but he occasionally has exaggeratedly feminine mannerisms. Shirogane insists the spell he put on Matsuri only affects his physical body, but Reo wonders aloud if an anatomically-female body itself is making his spirit trend toward the feminine over time. Whatever effect seems quite minor, but it becomes a recurring fear of Suzu's that Matsuri may become "a girl in heart and soul"—because she (initially) found Matsuri's male form more attractive and assumes that would make Matsuri fall for a guy instead of her.
    • Suzu can temporarily absorb ayakashi to use their powers, but this also affects her personality. Absorbing Shirogane made her a Cat Girl who fought more aggressively, licked herself, ran on all fours, carried objects in her mouth, and was way physical affection to Matsuri.
      Matsuri: What's gotten into you?! Stop licking meee!
      Kanade: She's in heat...
  • Claymore: When a Claymore over uses their powers and is transformed into an Awakened being, their personalities are changed, meaning a Claymore that would once thought they would have killed themselves if they transformed will no longer even consider doing that.
  • Bagi, the Monster of Mighty Nature plays this for tragedy. Bagi starts out as a Funny Animal, but turns more and more feral as time passes.
  • Makaku in Battle Angel Alita explicitly references this idea when he becomes quite intelligent after losing his initial large cyborg body and is reduced to an ambulatory head.
  • Mai Natsume of BlazBlue: Remix Heart was magically transformed into a girl, and gradually changes to naturally act feminine, stop seeing girls sexually, fall in love with a boy, and generally think of herself as being a girl rather than a boy in a girl's body. However, it's ambiguous how of this was the direct result of her transformation as opposed to her constructing a feminine identity as a disguise and liking it more than her original.
  • Inverted in one chapter of Cat-Eyed Boy. A Mad Scientist attempts brain transplants... but later discovers they can't be successfully performed, as the new mind housed in the body will eventually force its new body to match the one it was originally housed in.
  • In Darker than Black, Body Snatcher Mao needs Phlebotinum to maintain a human level of consciousness; without it, his personality is eventually overridden by the instincts of the cat whose body he inhabits.
  • Digimon:
    • As a general rule, Digimon become more brutish with stronger forms unless they cross the Bishōnen Line, while how much their actual personality changes varies by how much personality they have to begin with.
    • When Takuya first attains his Vritramon/Burning Greymon form in Digimon Frontier, he flips out and nearly takes Tomoki's head off, until one of Tomoki's tears falls into Takuya's eye, causing him to regain his sanity. While all of them had trouble controlling themselves in their beast transformations at first, only Takuya lost complete control. Except Izumi, for some reason; she attributes her ease of control to being a girl, but says it so obnoxiously that the boys feel ready to throw up. Izumi happens to also have a "beast" transformation that's basically still human in all but the most minor aspects and in fact qualifies as an in-universe case of Ms. Fanservice. Koichi also had no trouble, but he's the group's Sixth Ranger, had previous experience using it while still Brainwashed and Crazy, and by the time he joined up the beast transformations were So Last Season.
  • Dragon Ball:
    • In Dragon Ball, Saiyans who still have their tails turn into gigantic weremonkeys when exposed to the light of the full moon (or a similar enough substitute), becoming savage and violent no matter how docile they are in their humanlike form. Only Saiyans who have had the proper training can stay in control while transformed. Likewise, there's the Super Saiyan transformations, which turn even the nicest Saiyans (like Goku and Gohan) into the ruthless, cold-hearted warriors Saiyans are known as throughout the universe, with no desire other than to exact painful revenge on whoever angered them enough to trigger the transformation. Played With in that those who learn Super Saiyan eventually do learn to control the transformation and maintain a calm demeanor; with Goten and Trunks maintaining theirs when they’re exposed to their family.
    • In Dragon Ball Super, we get the villain Goku Black, who looks identical to Goku, but makes an indication early on that he originally did not have that appearance. Then we learn the reason for it is that he's actually a Supreme Kai named Zamasu who, out of envy and spite, stole the body of an alternate version of Goku. The curious thing about it is that his personality seems to have been altered slightly by this and he's taken on some of Goku's personality traits, particularly his desire for battle, and need to be challenged and grow stronger. Then after Black actually fights Goku even his speech pattern slowly grows more and more like Goku's. He also starts using some of Goku's fighting stances and techniques, although those are in part deliberate imitations. His penchant for meal metaphors to describe his opponents may also be an artifact of the real Goku being Obsessed with Food.
  • Zigzagged in Durarara!!. When Celty witnesses Kujiragi kidnap Shinra, she immediately goes into a rage. This causes her to become a large, black mass that directly correlates to her mental state. It is explained that in this form, unless reunited with her head, Celty will remain a mindless creature. However, when her head is returned, Celty loses all her memories as the Headless Rider and tries to return to her former dullahan duties. Luckily, Shinra sees through Celty's lie as she was only faking memory loss to make leaving easier. He manages in the end to sever her head and Celty returns to normal.
  • Fullmetal Alchemist: The Conqueror of Shamballa: Implied to be the case with Envy. Originally, while extremely ruthless, Envy enjoyed taunting people, was a Combat Pragmatist, and far more competent than his manga counterpart. In the movie, Envy has been trapped as dragon for the past two years and while he does speak, he mainly roars and hisses. During his battle with Ed, his behaviour more resembles a deranged animal than the arrogant trash-talker he was.
  • Himenospia: The queen-ranked wasp mutants can brainwash the females they transform on some level to gain their Undying Loyalty. Niho Kurono is the result of the mortally injured policeman Jirou Kuroda having his brain transplanted into the corpse of a already mutated schoolgirl in order to pretend being converted by Himeno and sabotaging her from within Himenospia. However, the cellular memory of his new female body leaves him unable to directly kill Himeno when he has the chance. Himeno even argues that he's become a whole different person than either his former self or the host he killed.
  • Negima! Magister Negi Magi:
    • Evangeline says that she acts much younger than her age because she's been stuck in a ten-year-old body for hundreds of years, and her personality is affected by that form.
    • When Sayo (the ghost of a 15-year-old girl) starts possessing a small doll, she starts acting much more light-hearted and childishly than before.
    • Averted when no one who uses the age-disguising pills ever acts differently unless it's a deliberate act to appear their "age". Ironically, it just makes Negi appear as old as he acts!
    • In a different kind of example, Albireo Imma's Shapeshifter Weapon allows him to become the person he transforms into: all the memories, actions, personality traits and instincts he observes of them are recorded into his many books (he has one for every person he's met). While he's subconsciously aware of his own presence, his body acts completely as the person would, so much that the person themself is essentially speaking. He's able to take over when he needs to, but for the most part the consciousness he imitates is in the driver's seat.
    • Also is Shiori's persona stealing ability which allows her to do largely the same thing, only for her she almost completely blanks out of consciousness to the point of thinking she's the person. However, she does leap instantly to Negi's defense and gets badly injured, though the only one to notice the lack of magic canceling was the Governor General. Also appears to have a crush on Negi... make of that what you will. Shiori is apparently aware, behind the scenes, of what "Asuna" does. But not the other way around, until she starts having feelings for Negi.
  • It's more subtle than most examples, but in Parasyte, after Migi infuses himself into Shinichi's heart and bloodstream to save his life, his emotions get duller and duller; he eventually reacts to a dead dog by throwing it in the garbage, earning a What the Hell, Hero? from Murano and making him realize what's happened. This prompts him to get better.
  • In Ranma ½, the vast majority of the shapeshifting characters gradually (though not consciously) acclimate to their cursed forms, learning how best to take advantage of their traits (such as size, flight, dexterity, or appearance) and paying heed to their natural instincts.
    • The most notorious example is with Ranma him/herself: although his personality and sexuality remain untouched, he grows considerably more comfortable with his female self, adopting feminine mannerisms and body language. Halfway through the series, (s)he thinks nothing of dressing up nice and going on dates with men (usually for some ulterior motive, but sometimes solely for the guy's benefit) even though the mere thought of wearing a skirt was anathema to him at the beginning of the story. But is it the body working on the mind, or just gradual desensitizing?

      In a Filler episode, Ranma gets knocked on the head while in girl form, making "her" believe she's really a girl (an extremely Girly Girl) who unfortunately changes into a boy. This painfully stereotypical behavior is probably just a reflection of Ranma's own mental image of what "normal girls" are supposed to be like.
    • An extreme example is Miss Hinako Ninomiya: due to an unspecified illness when she was a little girl and Happosai's chi-tampering, her body was stuck with the appearance of a ten year-old, even though she's somewhere in her late twenties. She acts like an obnoxious, bratty, bossy, hyperactive child while in kid form, but when she absorbs enough Battle Aura to temporarily restore her adult body, she's much more aloof and calculating.
    • Another good example is Ranma's father Genma, who actually seems to enjoy being a panda more than being a human, even going so far as to eat bamboo shoots.
    • Then there's Rouge, who turns into an Asura — a three-headed, six-armed, fire-breathing demon-goddess. Normally, she's a kind-hearted Chinese Girl, but in her cursed form she's got a case of A God Am I, and her temper disappears. Her irritability is partially explained as a result of the agonizing back-aches caused by having three sets of shoulders. In contrast, Pantyhose Taro turns from bishonen to minotaur-freakshow, without the slightest change in his Jerkass personality, although he seems less calculating and more instinctive as a chimera. In his case, he was baptised in the cursed spring soon after he was born. Changing from human to minotaur and back again for all your life is bound to result in a more consistent personality.
    • Kinnii, the killer from Jusenkyo, is probably hit by this trope as much as, if not more than, Rouge. A weapon of mass destruction for the "Jusenkyo Preservation Society", he's bulking, bloodthirsty and skilled with his sword; when he shapeshifts into a highly moral priest, he's nothing but a timid and regretful Nature Lover, who couldn't even believe (or likely remember) what his natural form is capable of.
  • In Show by Rock!!, Cyan is a human who was turned into a Cat Girl. She finds herself involuntarily performing cat mannerisms like meowing at times.
  • Used and subverted in The World God Only Knows. After a gender bending "Freaky Friday" Flip, the boy begins acting more feminine and gains an interest in dating sims for women. However, this is because the evil spirit inhabiting the girl's body is manipulating his emotions as the girl has no such problems while in his body. May also be the case for the goddesses unless Keima really is that much of a chick magnet. Diana has turned tsundere for Keima and Vulcan appears to be following suit.
  • Inugami Hatsune, a member of Psychic Squad Esper team "The Hound," suffers from this. Her powers allow her to technically assume the form of an animal (typically a canine) but the longer she spends in a form the more animal-like she becomes. Generally, the only way to snap her out of it is to calm her down by feeding her. This is the task of her partner, Yadorigi Akira, whose mind-switch powers allow him to throw prey in front of her to catch (and also forces him to experience the feeling of prey being eaten each time).
  • Once you become a vampire in the world of Kurobara Alice, you retain your old memories — but your mindset starts changing. In Dimitri's case, he becomes less emotional and more regal as the "heir" of the deceased vampire leader, Lord Bradley; when the story sets in the present, he's pretty much an Emotionless Boy.
  • In Fairy Tail: 100 Years Quest, most of the main characters, save Natsu and Gray, get transformed into youkai after being captured by the villain's minions. The process completely inverts their existing personalities, as they all turn violent and sadistic, happily self-identifying as their new forms, and seeming willing to remain youkai permanently. After they get turned back, they also don't retain any of those memories.

    Asian Animation 
  • In Pleasant Goat and Big Big Wolf: Mighty Little Defenders episode 33, goats Paddi, Tibbie, Sparky, and Jonie have just been transformed into wolves by General Wolf, and Paddi starts to chew on Uncle Gogoa's arm, Uncle Gogoa being a goat who wasn't transformed. Later, Paddi says he found Gogoa looking delicious, and Tibbie, Sparky, and Jonie admit the same.

    Comic Books 
  • Alpha Flight: Snowbird runs the risk of Shapeshifter Mode Lock if she stays in animal form too long—because her mind gets subsumed by the animal. She once had to be talked down by Wolverine while she was an actual wolverine.
  • Watchmen: Doctor Manhattan has been drifting away from humanity ever since he got his new body. Since he experiences all of his life simultaneously, he becomes distant, but having nigh-limitless power and an indestructible body certainly changed things for him as well.
  • She-Hulk: Jennifer Walters starts out as a somewhat demure lawyer — her transformation initially makes her far more aggressive and angry. Over the years, her continued use of the She-Hulk form has meant that the effect of her powered up form is simply a far more uninhibited version of herself.
  • Spider-Man:
    • In the "Six Arms Saga", Peter Parker's attempts at removing Spider-Man's powers using a serum backfires, at first he grows four additional arms, and then mutates into a gigantic spider-human hybrid called Man-Spider. He loses complete control of himself and attacks and overpowers many superheroes attempting to restrain him.
    • Dr. Curt Connors is a decent fellow, but when he mutates into the Lizard, he forgets who he was and becomes a violent reptile supremacist.
    • When Morbius stands trial for his crimes committed as a living vampire, She-Hulk gets him declared not guilty by reason of insanity, because when his body needs blood, he loses all control of himself. Later, in his third solo series, he messes up a cure and becomes more and more bat-like. He begs Spider-Man for help because he fears that soon, there will be nothing left of him except a raging beast.
  • ElfQuest: The explanation for why Timmain eventually abandoned her people, and later, why she remained white-furred even though it was dangerous: She was very deeply subsumed into the wolf-form she originally shapeshifted into for survival.
  • Hellblazer: Constantine faces off against a criminal's ghost that has possessed a man-eating junkyard dog. Constantine eventually manages to trick him by lying down and rolling over onto his back. The criminal is left unable to attack any further, as presenting one's belly is a sign of submission in canines.
  • An arc of JLA (1997) deals with General Ripper Wade Eiling swapping his mind with that of the Shaggy Man, a nearly indestructible monster. He reasons that his tactical experience combined with the Shaggy Man's brute strength will make him an unbeatable Genius Bruiser, but he is defeated when it turns out that his new brain isn't half as sophisticated as his old one. Though he retains his skills, knowledge, and intellect, Eiling's actual thoughts and awareness are a lot simpler and sloppier, and as a result he tends to forget details or fall for traps that he never would have as a human.
  • Johann Kraus from Hellboy used to be a German spiritualist who could project his spirit into an ethereal form until his body was destroyed while he was outside it. He was left permanently trapped in ghost form, forcing him to use a repurposed hazmat suit as a makeshift body, and as the series progresses, his personality gradually changes as he drifts away from a human perspective, becoming more aloof, distant, apathetic, and self-centered. It cuts the other way too, as when he temporarily gets a new body later on, the shock of being able to experience basic human pleasures again after decades of being stuck in a gaseous state causes him to become an extreme hedonist obsessed with eating, drinking, exercising, having sex, and whatever other physical activities he can think of.
  • Zigzagged in Daredevil in a somewhat convoluted manner. A brilliant but physically weak scientist named Dr. Karl Stragg transfers his mind into the body of the strong but dumb Enforcer named Ox. Stragg's intelligence gradually starts dropping, which leads to his death fighting Daredevil, while Ox finds himself getting smarter in Stragg's body. Later on, radiation experiments mutate Stragg's body, transforming it into an identical (but grey-skinned) copy of Ox's original body to match its current mind, but Stragg's mind also somehow resurfaces after he is fully transformed.
  • The Incredible Hulk: On occasion, the situation with the Hulk is that Bruce transforms into the Hulk's body, but retains his own mind (rather than switching personalities). Often, however, Bruce still finds it very difficult to think or keep calm while in typical Hulk form.

    Fan Works 
  • DC Nation: An unfortunate side-effect of Fauna's powers. Yes, she can partially shape-shift into most animals, as well as speak to and persuade animals to ally with her, but the harder she pushes her abilities, or the more wounded/angry she becomes in a battle situation, and the less she thinks like a human and the more she thinks like a beast. Worse, she remembers almost nothing of what happened during one of those "freak outs" afterward. As she told Changeling once, "You keep the mind of a man when you shift; I don't."
  • Izuku in ''Deku 10 is very notably affected by whatever alien form he transforms into. As Bullfrag, he gains a notable sadistic streak and wants to do good by the Incursean empire.
  • In the sequel of Child of the Storm, Harry and Carol discuss (in reference to Harry being sorely tempted to turn Jean's cheating boyfriend into a frog) the ban on forcibly transforming others into animals under the Laws of Magic, and the laws of the Wanded magical world, because of it has this kind of effect - namely, they essentially become the animal, if they spend too long as one, effectively killing the person. Temporary transformations, such as those induced by Fred and George's Canary Creams (which in any case don't seem to be totally inhuman transformations, since the person who undergoes it remains the same size) skirt the line, but are broadly fine.
  • George in With Strings Attached. His ring allows him to transform into any animal he can imagine, but becoming that animal also causes him to gain the senses, instincts and tastes of that particular creature. A few times, he has to exert his own will to keep from doing something inappropriate, like eating something (or someone) he's not supposed to.
  • This is a core theme of Becoming Ponies. The counterparts are all having their personality slowly overridden with that of their associated character, and some of them don't even realize it.
  • Harry faces this problem in No Longer Human since (as the title indicates) he isn't fully human anymore but a hybrid of a phoenix, basilisk, and human. When Ginny comes to him crying that the attacks were her fault and that she was controlled by Riddle's diary, all Harry feels is annoyance that she's getting his shirt wet and anger that she "allowed" herself to be controlled.
  • The Parselmouth of Gryffindor has two variations on this same trope:
    • In an unusual willing example, the Voluntary Shapeshifter Maximilian can (and does) alter parts of his brain to become better-suited to whatever he's doing, such as turning off the part of his brain that induces boredom if he's studying. Other characters are understandably creeped out by this.
    • When part of Lord Voldemort's soul is transferred into one of the Hogwarts statues, said Horcrux finds himself unable to harm anyone or leave the castle, because all of the statues, whether animated or not, are bewitched to be loyal to the Castle as one of their core values so that they may act as protectors of Hogwarts in cases of emergency.
  • In Walk Through the Valley by Vathara, Hiko uses LEGO Genetics to transform himself into a kiryuu alterant, a felinoid alien from the planet Satoyama. Upon becoming half-man, half-kiryuu, he takes on the kiryuu's territorial instincts despite being a drifter who previously never stayed anywhere more than a year at a time (except for his stint on Satoyama). Within five years, he finds himself killing in an Unstoppable Rage just to protect his territory. Later, he finds himself with a dying eight-year-old escaped slave boy (Kenshin) and the only way to save him is an Emergency Transformation into a kiryuu alterant. Previously, Hiko had been a borderline Child Hater who wouldn't have bothered. Similarly, Kenshin was hostile to a friend who approached the cabin despite caring for her, until he was able to rationalize her as a member of his pack to get around it.
  • Diaries of a Madman: Navarone struggles with this, being particularly vulnerable to pony pheromones whenever he's turned into a pegasus. When gender switched for a prolonged period of time, he also has trouble dealing with certain urges while female.
  • This is a major theme in The Land Before Time fanfiction The Seven Hunters. Although Littlefoot and the other members of the gang retain their personalities after their transformation into carnivores, they slowly begin to suffer from a personality shift as time goes on. They even begin to enjoy their hunts despite the realities of what that entails.
  • A variation of this features in the Supernatural/Sherlock fic "The Case of Identity Switch" when Dean Winchester and Sherlock Holmes swap bodies, as Dean finds himself making Sherlock-esque intuitive leaps that he would not normally be capable of on his own. Castiel attributes this to Sherlock's faster brain allowing Dean to make those kind of intellectual leaps, where Sherlock has to concentrate harder in Dean's body to make his usual deductions as Dean's brain isn't used to thinking that fast even if Sherlock's mind retains the accumulated knowledge that allows him to make most of his deductions.
  • In As We Chase the Sun, spending the better part of fourteen years in the form of a wolf as an animagus has led to Bellatrix practically forgetting that she even was human originally, only able to recognise Sirius, Andromeda and Narcissa as family through scent and other primitive measures. However, this has the advantage of making her more willing to essentially reconcile with Sirius and Andromeda in particular, as her wolf-psyche focuses more on the obvious idea of them as "pack" without thinking about the more complex issues such as the circumstances that drove her to sever ties with them in particular.
  • Features in the Farscape fic "In the Flesh", when Moya is attacked by a crew who have acquired the weapon that caused the crew to previously switch bodies ("Out of Their Minds"). While this attack initially appears to have only caused Aeyrn and Pilot to switch, the crew soon realise a more serious problem has occured as Chiana has swapped with Moya. As observed by Pilot, this not only explains Moya's "silence" since the switch as Chiana-in-Moya has basically shut down to protect herself from the scope of trying to understand a Leviathan body, but he also worries about the possibility of Moya causing harm to either her mind or Chiana's body trying to cope in a form so utterly unlike what she's used to.
  • Invoked in Lost in Camelot when Dyson recalls how he first met Lancelot, as he spent several weeks in his wolf-shape to escape his human guilt at the loss of his friend and his exile from his pack, as his wolf self didn't have to deal with his more complex emotions of guilt and grief.
  • Discussed in "Morningstar Family Values" when Trixie asks if Sabrina could show her magic by turning Trixie into a frog. Sabrina explains that it wouldn't be worth it because Trixie's brain would become a frog's during that transformation, so she wouldn't be able to remember it and would retain some unwanted frog instincts for the next couple of days, such as trying to catch flies with her tongue.
  • At least suggested to be the case in the Power Rangers Zeo fic "Memory Lapse", which reveals that Shawna, a close friend of the previous Yellow Ranger Aisha, was actually Aisha's girlfriend. When Aisha chose to stay in the past after her quest for the Zeo Crystal and send Tanya back to the present instead (as depicted in "Hogday Afternoon"), Billy speculates that this was because Aisha's younger body stopped her remembering Shawna with the same degree of emotional attachment that she would have felt as an adult.
  • The Stargate SG-1 fic "A Dog's Life" features this in both directions. When Daniel's essence is temporarily displaced into a dog's body while a non-corporeal entity uses his body for a couple of months, he often has to deal with resisting his dog instincts, such as being disturbed when his dog body reacts to the presence of a female dog in heat. Later, when Daniel misses the planned deadline to regain his body, the alien returns to Earth on its own accord because Daniel's body had an innate morality that compelled it to come back, recognising that Daniel wasn't at fault for his absence (Daniel was unaware that months on the other planet were slightly shorter than on Earth and missed the meeting by a couple of days).
  • In Consequences of Unoriginality, Emeris is a human who was turned into an alicorn. For this reason, though it disturbs him, he finds mares sexually attractive. Subverted when he is depowered, revealing that his body is actually a Cosmic Horror and his pony nature is a way of protecting his mind from being twisted by by that body, because Friendship is Magic
  • In the Avengers fanfic That Darn Cat, Loki is transformed into a cat by Odin as punishment, and sent back to Earth with Thor. While he mostly retains his personality, sometimes that 'cat instinct' will override it — such as when he's confronted with Darcy's knitting and can't leave the yarn alone, or when someone scratches behind his ears. The fact that he can't fight the instinct just makes him even angrier over the whole situation.
  • In the Discworld fic Hear Them Chatter On The Tide, a powerful anthropomorphic personality who has been lost to the world for at least a thousand years is transformed into a sort of animal. The long-lost virtue, specifically, is Bissonomy, transformed into a shoal of oysters by a jealous fellow god. This demiurge has human followers whose goal is to restore her to human shape and potency. The problem is that as the Goddess Cult of the Blue Oyster discover, Bissonomy has spent so long as an oyster that she has forgotten she is human.
  • In the Pokémon fanfic Morphic, most of the kids' personalities are influenced somewhat by the Pokémon they were fused with. For instance, Peter often makes twitchy bird-like movements like a Taillow, and Will (a Meowth morph) displays a lot of cat-like mannerisms. Additionally, it's revealed late in the fic that all of them have varying degrees of battle lust, just like "actual" Pokémon.
  • In the Oversaturated World, it's the entire conflict of a story. In What Shy Did On Her Summer Vacation. Fluttershy decides to spend her summer vacation as a tree. This slowly leads to her becoming more distant and less caring about human concerns until, at last, she stops moving and starts to fade from consciousness entirely. Mildly subverted, in that it's stated it was less her state as a tree that caused the shift and more an unforeseen circumstance of the spell cast to turn her into a tree.
  • In Destiny is a Hazy Thing Daiki's worldview has been seriously warped as a result of spending the last ten million years as a human. Before that he was Yog-sothoth.
  • After being made 22 for a night in Dodging Prison & Stealing Witches, Hermione no longer has the hormones that affected her thoughts so much but still remembers her very physical attraction to Harry.
  • Loaded Bones: Yami Bakura notes that most of his proclivities come from Ryou's brain.
  • Deserted Distractions: Yami Bakura laments that this is the reason he's attracted to Tea; since Ryou is his host and likes her, he does too.
  • For Love of Magic: Harry theorizes that Tonks' increased aggressiveness and attraction to women (years prior she only had minor interest and she's now fully bisexual) is due to her granting herself male genitals with increasing frequency (as part of kinky sex games with Fleur) which is messing with her hormones.
  • Mergers has this grow more and more prominent the more Pokemon DNA you have, with Brock losing the ability to speak like a human.
  • This is implied in Chapter 24 of The Portal when Blizzard says to Static that he believes that their transformation from humans into dragons has changed the way they think as well as their physical bodies.
  • Universe Falls: In "Monster Falls" (Inspired by the Gravity Falls Monster AU) Bill Cipher and Yellow Diamond's combined attack turns the people of Gravity Falls into various monsters like werewolves, ghosts, gorgons etc. and the turns the gems into corrupt forms. While the gems still maintain their personalities, albeit without the ability to properly communicate, as time progresses the GF citizens become more like their monster selves, Cervitaur Dipper becomes more skittish, Mermaid Mabel acts more like a fish, Gorgon Pacifica embraces her predatory instincts and so on.

    Films — Animated 
  • Brave: This was a problem for Queen Elinor and the prince in the legend when they are turned into bears.
  • Beauty and the Beast: According to the director's commentary, the spell affected the Beast's mind as well as his body; the longer the spell lasts, the more feral he becomes. When Belle arrives, he has to re-learn how to read and eat with utensils, and if she had never come to the castle, he would've eventually stopped speaking, stopped wearing clothing altogether, and would've gone to live in the woods, becoming a beast both inside and out.
  • Played for Laughs in Soul, Joe takes on some catlike mannerisms while in Mr. Mittens’ body, i.e. sleeping in a sunbeam.
  • In Turning Red, Mei gains the ability to transform into a huge red panda. Whenever she's transformed, she throws her arms in the air when she's scared. This is actually a threat display used by red pandas wherein they make themselves look larger in order to scare off predators.

    Films — Live Action 
  • In An American Werewolf in London, David Kessler transforms violently into a werewolf, screaming for help as he becomes less and less human. As a werewolf, his only instinct is to kill and to feed, violently ripping his random victims apart. As he is doomed to continue this so long as he lives, his deceased friend Jack begs him to kill himself. The second time he changes, David is briefly calmed when the young woman he fell in love with attempts to save him from being shot; Sadly, he is too far gone and thus killed right in front of her.
  • In the My Favorite Martian movie, the alien polymorph gum can alter one's personality, depending on the alien. This comes up later, where the hero's nice and mild-mannered girlfriend chews one, turns into a giant alien monster, and kills a couple MIB guards, even eating one. Afterward, she acts as if she had just been in a drunken party.
  • Subverted in the Day of the Dead (2008) remake. Bub is a vegetarian and thus doesn't want brains, and he follows orders due to being a marine and/or having a crush on Cross.
  • Subverted in Land of the Dead. The gas station attendant zombie initially remembers that he's supposed to do something with the gas pumps. As the movie progresses, he regains more and more of his humanity, including compassion for his fellow zombies, tool and gun use, and even leadership.
  • In The Fly (1986), the scientific genius Seth Brundle fuses with a fly, and as his body slowly begins to morph horribly, he realizes that, to his terror, his personality is being overridden by the instincts of the mindless insect. Arguably, the last we see of his original personality is when the crippled wreck that Brundle has become mutely begs for death.
  • Captain America: The First Avenger: To some degree, this is inverted with Schmidt who developed his... unusual features in response to the serum because the serum hadn't been perfected yet and he was an evil man at heart. As its creator said, good becomes better, bad becomes worse.

  • In The Evil Wizard Smallbone, whenever someone is shapeshifted into an animal, they become that animal in mind and body unless they've been trained on how to keep their mind intact. This is how the villain keeps his minions in line.
  • Animorphs used this a lot:
    • Every animal morph came with its own set of animal instincts; these were mostly useful, but some morphs (such as an ant) had instincts so strong they risked permanently overpowering the human personality.
    • Termites caused even greater problems, since they were entirely controlled by pheromones the bodies were hard-wired to obey.
    • Taxxons are horrifying, as they are completely consumed by Horror Hunger, causing them to instantly consume anything even remotely edible around them (including their injured comrades). Yeerks with Taxxon host bodies cannot stop the feeding once it starts and can barely make the host body focus on anything besides feeding; morphing into a Taxxon causes similar issues. The hunger is so bad that a group of dissident Taxxons agree to help the Animorphs in exchange for being allowed to morph into some less-ravenous forms and stay in those forms for more than two hours.
  • In The Belgariad, Belgarath points out that transforming into an eagle wouldn't necessarily help you travel faster, because you were likely to get sidetracked by every tasty animal below, observing that while they look magnificent, eagles are really very stupid birds. More generally, this is a hazard of shapeshifting, with Belgarath dedicating an extended passage in his self-narrated prequel to explaining the insidious effect that taking animal form can have, since the change is absolute - an extended period as a wolf, for instance, leaves him interested in the idea of a wolfish life and taking up with a young female wolf who's taken an interest in him, daydreaming of the hunt, companionship of a mate, cubs, etcetera. Interestingly, the reverse also applies, as his wife, Poledra, was originally a wolf (in fact, she was the young female wolf mentioned above), and after giving up on the idea of him mating with her as a wolf, changed into a form he'd find more attractive - a woman. The narration makes very explicit that she is now a woman - one who used to be a wolf, and could transform back whenever she wished (among many other things), but still a woman.
  • Jack Chalker, as can be expected by the prevalence of transformation plots in his writing, makes frequent use of this.
    • Downtiming The Night Side: Used specifically to avert Different for Girls. Also applied to most of the transformations that are a core theme of much of his work, particularly in the Well World series and even one-offs like Web of the Chozen.
    • Especially nasty in the Soul Rider series, where the revolutionary state of New Eden imposes this on its female population by a binding spell. A transformed "Fluxgirl" is literally ruled by her body, which now craves constant sex, has difficulty with concentration on long-term projects, and cannot read, write, calculate, or figure out complicated machinery.
    • Chalker also specifically inverts this trope in The Identity Matrix, where the body can be made the plaything of the mind by making mental adjustments that influence the endocrine system, affecting things like muscle development and fat distribution.
  • A curious variant in Charlie and the Great Glass Elevator: When Grandma Georgina (who is in her late 70s) is aged to 300+ years old via a Rapid Aging formula, her memories change to reflect the times she would have been born in and lived through had she come to this point naturally. (Her earliest memory is arriving in America on the Mayflower.) When she is returned to her natural age, these memories apparently disappear.
  • In H. P. Lovecraft's Cthulhu Mythos stories, the outer god Nyarlathotep is said to have a thousand forms. Each form is essentially a separate entity (it's implied that he can even manifest several in forms at once). As such, the behaviour and personality of different forms can be completely different. This is only vaguely implied in the original works, but considering that Nyarlathotep's different forms functions essentially identically to the Avatars of Hindu mythology, this is indeed probably the case, although a central intelligence connects them all in some sense.
  • In Oath of Gold, the third volume of Elizabeth Moon's The Deed of Paksenarrion, the Kuakgan talks about this with Paks, who was unable to continue her life as a paladin-in-training after being captured, tormented, and rescued, and who is at the brink of suicide when he finds her leaving her worldly goods in his grove's offering-bowl. She also hasn't eaten properly for quite a while, and has a lot of half-healed wounds. The analogy he draws between the mind and the body is that of the snail and the snail-shell; if you poke holes in the snail-shell, will the snail live?
  • Terry Pratchett's Discworld series plays it relatively straight. One notable example, and a reference back to it in a later book, likens the mind to water and the body to a jug or vase. The water is only water, it does not become the container, but it does take on the container's shape.
    • The longer Discworld werewolves spend in wolf form, the more they start to think like a wolf. The reverse is also true: They become more human the longer they spend in human form. They never entirely become one or the other, this is the true "curse of the werewolves".
    • The same is true of Borrowing: The longer you inhabit something else's brain, the more you start thinking like that something else. In Equal Rites, Esk nearly starves to death because she loses track of her human self, but doesn't have the proper instincts to feed herself as a falcon.
      • Later in the book there's the bit where Granny Weatherwax Borrows the Unseen University, and thinks like a building upon coming out of it.
    • The Great God Om points out in Small Gods that the shape of the body influences the shape of the mind, so if you spend too long in the body of, say, a tortoise, you begin to think like a tortoise.
    • It is also true on the Disc that the body is sometimes a plaything of the mind. In Witches Abroad, a cat is transformed into a human just by making him really believe that he's human.
    • A major theme of Thiefof Time
      • When the Auditors create human bodies for themselves, they eventually start feeling emotions. The end result is a mix of Auditor and human that has serious trouble being either.
      • The point of the "water in a jug" analogy is Myria LeJean's realization that it is wrong; for a mind in a body, the "water" is truly changed by the jug.
      • The History Monks have a Dalai Lama-type figure whose wisdom reincarnates throughout the ages and is present from birth. As his current incarnation is a baby, however, his sage wisdom often loses out to sentiments like "wanna bikkit".
    • Addressed in a more technical form in The Science of Discworld, in which the complicit relationship between physical brain processes, external experience, and minds are discussed.
  • In a Dragonlance short story, an If I Can't Have You… plot winds up with most of the cast shapeshifted. If they do not wear something belonging to their human (or otherwise) selves, the human mind will eventually succumb to the animal form. Taz comes very close to being permanently stuck as a squirrel.
  • The Dresden Files:
    • One of the laws of magic is to never change someone's form against their will: it will eventually destroy their mind, leaving just a normal animal. Changing your own form is allowed — partly because it's consensual by definition, partly because people who transform themselves instinctively protect their minds to avert this trope — but still carries risks.
    • A good example of a first-person viewpoint to this trope is Harry's transformation into a hexenwulf in Fool Moon, and subsequent gradual loss of control to the monstrous wolf's beastly instincts. Hearing it from his narration is pretty freaky, and when he turns back, he's sickened and horrified.
    • At one point in Changes, the main characters are transformed into a pack of hounds as part of a plan to sneak into the stronghold of the Red Court vampires. Despite everyone involved being willing to undergo the change, the transformed characters slowly start thinking more and more like dogs, gradually forgetting the urgency to turn back into humans once they get where they need to go.
    • In Skin Game, the shapeshifter Goodman Grey transforms into a different man, but immediately starts exhibiting the man's nervousness and fear at the situation he was in before he died.
  • Dr. Franklin's Island has a pair of teenagers transformed into a birdlike monster "human enough to horrify" and something like a small manta ray, respectively. Before, they would have considered their minds changing to be the worst thing on a great pile of terrible things, but after, Semi reflects that it's a help. As a fish, she doesn't get bored and is perfectly content to swim and daydream, and Miranda finds great joy in being able to fly. More of a problem is when instead of coexisting with their human priorities and thoughts they replace them.
  • In Earthsea stories by Ursula K. Le Guin, shapeshifting works this way: the longer a wizard stays in a given form, the more his mind is taken over by that form's instincts, and the more he risks forgetting he was ever a man. Legends say many mages turned themselves permanently into dolphins this way, and one tragic fable concerns a wizard who so enjoyed turning himself into a bear that he ultimately became the bear and killed his own son.
    • In A Wizard of Earthsea this happens to protagonist Ged. He almost loses his mind when he is forced to flee over a long distance as a hawk. By the time he escapes, Ged is so far gone he does not remember magic, so he cannot change himself back. Instead he flies — probably by animal instinct — to a familiar place: the house of Ogion, The Mentor. Because Ogion is a powerful wizard who knows Ged's True Name, he can restore his former student's body to human form. However, it takes time for Ged to recover psychologically: weeks pass before he can even speak.
  • This trope is a recurring element in Fablehaven. When you transform (with the exception of the Eternals' guardians) you become yourself if you had been born a member of that species. It's most used with magical creatures that have human avatars, but it was a major plot point in the first book when Grandma had to fight her chicken instincts to get a message through.
  • In Robin Jarvis' Hagwood trilogy, the insect monster known as Frighty Aggie was once a werling named Agnilla Hellekin. She was so skilled that she could wergle (that is, transform) into any forest creature. However, she wanted a bigger challenge, so decided to try wergling into an insect. This had never been attempted by anyone before and was regarded as highly dangerous. Still, she successfully managed to do so three times, but each time her mind was being irreparably damaged. On the third try, she could not wergle back to her original form and permanently became a grotesque insect monster with no memory of who she had been before. Her story became a cautionary tale to all werlings to never try wergling into shapes that were forbidden to them.
  • This trope plays both ways in Harry Potter: If a person is involuntarily transfigured into an animal (and this includes werewolves), then they lose their human mind for the duration of the spell. However, with years of study, and at great risk, a wizard can train him/her self to transform into an animal at will and retain their human mind — mostly. (Wormtail suffered no ill effects from being a rat for twelve years straight, but Sirius sometimes turned into a dog to ameliorate the stress caused by Dementors.)
    • Sirius also once says that James had always joked he had a much sweeter disposition as a dog, implying that there are at least mild changes in personality/attitude which reflect the behavioral patterns of the animal they transform into. Of course this aspect is debatable because of the fact that the wizard doesn't choose which animal they transform into, they find out only once they've completed the training and see what they become (much like the Patronus charm), and implies that the animagus form reveals, in part, the true nature of the character in question. Even so, it is easy to see that a character like Sirius may have very playful and loyal dog-like nature, but frequently behave in harsh or unforgiving ways due to the emotional and psychological trauma of his human life, which might be less at the forefront of his mind because of the less linear nature of the dog's mind. It is also the way he escaped Azkaban without notice — the Dementors could not detect the less complex dog mind, and therefore didn't realize a human was leaving the prison.
    • Likewise, a Horcrux is Nigh-Invulnerable because it's the inverse of a mortal—the spirit it contains will instantly die if it's destroyed, but the physical self regenerates.
    • The author also noted that animagi tend to suffer a sharp decrease in IQ when in animal form, presumably due to the shrinkage in brain size.
  • In Heralds of Valdemar many mages are capable of taking animal shape, but rarely do for reasons much like on the rest of this page. One Tarma and Kethry story features a mage who's been spending far too long in bear form and losing her grip on reality. Kethry explains why this is a problem.
    Kethry: "When you shapechange, you become the thing you've changed to. You're subject to its instincts, its limitations. Including the fact that there's not enough room in a beast's head for a human mind. That usually doesn't matter much. Not so long as you don't spend more than an hour or two as a beast. You don't lose much of your humanity, and you probably get it back when you revert. But it's not guaranteed that you will, and the stronger the animal's instincts, the more of yourself you'll lose."
    • Winds of Change has Dawnfire doing an Animal Eye Spy when her human body is killed, leaving her soul anchored to a hawk. This is a magic, smart hawk but she knows she has only so much time before her memories and sense of self degrade, leaving her as, well, a smart hawk that responds to her name. Another character who knows something about "transfer spells" proposes moving her to a body with a large enough brain that she can stay herself, or to "something like a sword".
  • The Host (2008): The Souls are strongly affected by natural instincts and sometimes memories of their hosts. If a human host loved someone before the transformation and this feeling was mutual, its very likely their souls will become a couple. It happens even if souls haven't met each other before.
  • Industrial Society and Its Future: Discussed by Kaczynski as due to desires, feeling etc being things which can be physically affected this opens up an ability to manipulate our behavior using drugs or other means. He fears too this will only increase into total control.
  • Journey to Chaos: When Eric mana mutates into a grendel, his personality and worldview permanently change. Even after his sanity is restored, he thinks like a monster. He still has his human memories but they are interpreted by his new monster mindset. He soon realizes that the mindset for monsters and mercenaries, and monsters and mages are striking similar and so there is little true change in his core personality.
  • "Lady Into Fox" is about a refined elegant woman, and her husband who was a fox hunter. One day she—with no explanation—turns into a talking fox. They try to live their lives as best as they can, but she gradually starts to lose her mind. She becomes more interested in chasing rabbits; soon enough she slowly loses her humanity, forgetting who her husband is and losing her ability to talk. The once well-mannered dainty lady is now eating live rabbits in the living room, with blood everywhere. It was never explained why she transformed but it's implied God or some karmic force punished her husband for killing foxes for a living.
  • The Magicians: Taking on the form of an animal results in the shapeshifter often being at least partly overtaken by their instincts, a fact that the Brakebills facult openly exploit: in order to send the students to Brakebills' southern campus in the Fourth Year, they transform them into geese, entrusting that their instinctive ability to navigate will allow them to travel to Antarctica. Later, as part of their Training from Hell, they're deliberately humiliated in a lesson in which they must transform themselves into arctic foxes — and then experience the logical consequences of combining animal instincts and several months without sex.
  • Mithgar: A shapeshifter in their animal form is said to have the mind of that animal, albeit one that will occasionally have thoughts similar to those of a human. The flip side of this is that a shapeshifter in human form will occasionally have thoughts similar to those of the animal they transform into.
  • Old Kingdom: Lirael can make skins that allow her to take on the form of an otter, or a bear, or an owl, but each one alters her temperament for a while, even when she takes them off (the otter-skin gives her a great craving for fish, for example).
  • The Prefect: One glitter belt polity consists of disembodied minds interacting entirely virtually, but recognizing that The Mind Is a Plaything of the Body, they maintain their human experience by becoming not brains in jars but instead brains-and-endocrine-systems in jars.
  • Realm of the Elderlings: In the Farseer Trilogy, Fitz fakes his death by abandoning his body and binding his mind to Nighteyes's. When he is brought back into his body it takes him half a year to remember how to be human, and even then he is much more wolfish than before.
  • Seraphina: In this fantasy world, dragons can shape-shift into human forms called "saarantrai" ("saarantras" in the singular). While in saarantras form they still retain their near-eidetic memories, pedantry, and innate logical processing, they can be affected by intense human emotions, which they lack in their natural reptilian form. For this reason, they rely on Emotion Suppression a la Vulcans while shape-shifted.
  • Seven Years Awesome Luck: Trick has picked up many cat traits from his seven years, from rubbing his head against friends, to chasing laser pointers, to hunting mice. He's possibly especially susceptible since he likes being a cat.
  • A Song of Ice and Fire: The skinchangers (who do not physically transform but can telepathically possess certain animals) have trouble remembering their human selves. When Bran Stark is being taught to control his power, he is told to do certain things as a wolf to help keep his mind in control. He keeps forgetting to do these things, and as a result he acts largely on instinct while in wolf form. Some of the older, more experienced skinchangers seem to be able to use their human intelligence more effectively, however, though it is mentioned that certain forms increase the risk of losing touch with humanity. When a skinchanger's human body dies, they can possess their animals to keep on living, but eventually the animal forgets its human life and becomes an ordinary beast.
  • The Stormlight Archive: Parshendi have the ability to change forms suited for specific roles, and they shift slightly in temperament depending on form. Dullform are extremely stupid, mateform are playful and sexual, workform are non-confrontational to a fault, and stormform is flat-out Demonic Possession. Nimbleform and warform have minimal mental changes, but warforms still enjoy obeying orders from their lawful superiors.
  • Strata: Marco was bought up on Earth among humans and even has papers to prove he's legally human. He still possesses the Kung instinct to fall upon anything that threatens or surprises him, and destroy it utterly.
  • Tales of the Five Hundred Kingdoms: We're told that only the most powerful Sorcerers or Sorceresses can transform a person into an animal without that person losing his mind to the animal. However, since the books focus on Godmothers, we don't see this in action.
    • In The Fairy Godmother, Elena transforms Alexander into a donkey, but has to give him regular time as a human.
    • In The Snow Queen, Aleksia takes several animal forms, but even as a polar bear (which has a large enough brain to "fit" a human mind into) the animal instincts get stronger the longer she remains changed.
  • Three Men in a Boat: There's a several pages long passage detailing how a person's mood depends entirely on what they are eating, and what this food is doing to the body.
  • Tortall Universe: In The Immortals, Daine finds that thanks to mind-speaking with and turning into animals, that she can no longer eat wild game. For a while she can still eat beef, pork, chicken, and fish because she's never had an interest in inhabiting the minds or taking on the shapes of barnyard animals or fish, but by The Realms of the Gods she can't even do that.
  • Wild Cards: Jeremiah Strauss is a shapechanger who turned himself into King Kong and then spent several years acting like a gorilla and trying to carry blonde women to the top of the Empire State Building. Later transformations into a werewolf from The Howling and the Creature from the Black Lagoon almost turned out badly as well.
  • Wren To The Rescue: The protagonist is turned into a dog, and is explicitly warned that the longer she spends in that form, the more difficulty she will have retaining her human mind; she gets out of it with no more than a few transitory dog habits. In the sequel, her friend Tyron is forced to spend a significantly longer time as a dog and only retains his identity by extreme effort.
  • Xanadu (Storyverse): Many individuals develop compulsive tics, habits and instincts to match their new bodies. In "Against Type", Nicodemus, who is transformed into a giant rat, gains the innate twitchiness and nervous disposition of a prey animal, strongly prefers to arrange his bedcovers into a nest in which he can completely hide himself, and develops a compulsive habit of stealing and hoarding small shiny objects.
    Nico cringed a little as his friend and co-worker lifted it into the back of the Honda. "It's mostly just junk. Useful junk, I hope. But junk. I... I can't help it. I've been able to fight off a lot of ratty behaviors, but I need an outlet, so... um. Guess I'm a packrat."
  • Xanth: In the very first book, Magician Trent can change anyone into any animal. The form comes with instincts built in. Trent said something like (paraphrasing): "If you're a turtle, unless you have the instincts of a turtle, you couldn't survive as a turtle." Later books introduced a character who could shape-shift but didn't get the instincts, making it a much more limited talent. This was due to her demonic heritage; it wasn't even her personal magic.

    Live-Action TV 
  • In The 10th Kingdom, Prince Wendell swaps bodies with a dog and gradually starts thinking like a dog, the dog also slowly starts thinking more like a human (but never quite gets it) although this may simply be training.
  • Andromeda: The physical avatar that Harper builds for Andromeda is initially just a more solid presence for the ship's AI than the holograms she normally uses, but over time, dealing with humans and aliens on a more intimate and physical level, Rommy develops a more emotional and independent personality. Even the holograms have a slightly different personality than the 2d avatars she uses on consoles; occasionally the three get together for consultations.
  • BrainDead — possibly. As of this writing (Season 1, Episode 3), it is unclear whether the alien bugs' becoming embroiled in our political squabbles is all part of their plan for conquest or is in fact a derailment of those plans, perhaps because they have no conception of ideology and take their absorbed opinions for Absolute Truth.
  • Buffy the Vampire Slayer:
    • When Giles is turned into a Fyarl demon in "A New Man", his instincts tell him to smash things, like Fyarl demons are wont to do. The more time passes, the harder it becomes to keep those impulses under control.
    • Oz's werewolf attraction to Veruca is clearly hard to keep in check, but he manages. That is, until sunset on a full moon night — he loses it after the first stages of transformation.
  • Doctor Who:
    • The result of regeneration. While certain deep traits and values are maintained between every incarnation of a Time Lord, other parts of the personality can become massively different, in addition to being completely loopy and extreme for a day or so as they settle into each new personality. As the Fourth Doctor comments in his initial episode, "A new body is like a new house — it takes some time to settle in." Every Doctor (with the exception of the Ninth, whose initial regeneration wasn't seen) gets an initial storyline about figuring out what their own personality is like, and every Doctor seems to have their own view on how much of a change this even is: One viewed it as a straightforward continuation ("it's not over!") but his successors as "replacements"; Three's was tangled up with Buddhist symbolism concerning change and renewal; Four viewed it as a death, although one he was happy to accept by the time it happened; Seven thought it was a change of perspective; Eight described each incarnation as a different and separate life; Ten described it as an actual death where "some new man goes sauntering away"; and Eleven's comments suggest that they're like the phases everyone goes through.
    • "Daleks in Manhattan"/"Evolution of the Daleks": Dalek Sec merges himself into a Dalek/Human hybrid for the sake of experimentation and prolonging the Dalek species. Which in turn he became kind, rational, and outright resented what he used to be. The other Daleks didn't take that very well.
  • Dollhouse. In "Instinct" Echo is programmed to believe she is a mother with a baby, not only with her memories but also her glands to induce lactation and parental bonding. Thus even after Echo's memories are wiped, she still instinctively seeks out the baby to protect him.
  • It's implied in The Flash (2014), and confirmed in a deleted scene, that Eobard Thawne Took a Level in Kindness to some extent and became more mellow in his Harrison Wells disguise because he used DNA harvested from the real Wells. Future incarnations of Thawne still have the Wells disguise, but are more openly evil and violent.
  • A crossover episode of Kamen Rider Gaim feature the story of Ryoma Sengoku who placed his brain into the robotic body of Hakaider which ended up making him behave more and more Ax-Crazy. Something that he found out much to his horror when he returned back to his human body.
  • Quantum Leap saw a little bit of this at times, usually attributed to the "Swiss-Cheese Memory" side effect of Leaping. In one episode Sam leapt into a retarded man and exhibited some of those same traits in living his day-to-day life.
  • Space Cases: In the Personality Swap episode, turning human doesn't grant Radu any new powers like the others, except that he automatically assumes the role of the leader and starts ordering the others, who follow him, just not entirely happily. Apparently, a superiority complex comes with human DNA, though it should come as no surprise since Harlan explained this while he was still human. Rosie's and Bova's personalities are also characteristic of their species and swap accordingly.
  • In the Star Trek: The Original Series episode "By Any Other Name", the Kelvans (huge emotionless hundred-armed aliens from the Andromeda galaxy) take human form. They eventually start thinking like humans, including having human emotions.
  • Star Trek: Voyager:
    • Members of Species 8472 suddenly become much more willing to negotiate after taking-on Human disguises in the episode "In the Flesh".
    • In a reverse example, Ensign Lindsay Ballard is unable to reintegrate back into her life on Voyager after having been transformed into an alien.

    Newspaper Comics 

  • Religions that believe in incarnated gods have a variety of beliefs in the degree of influence those bodies have on the god during the incarnation, though usually (universally?) the essential nature of the god remains the same throughout. Christian theologians and sects disagree on the nature of Jesus' humanity, some (for example) holding that Satan could never actually tempt him with food or power, while others holding that he must have or else the 'temptations' were meaningless. Hindu stories strongly imply that incarnated gods will usually forget their divine natures entirely while on Earth unless enlightened to them.
  • In those belief systems that hold with souls' preëxisting birth, some hold that the soul's essential nature and fate are eternally mutable, others that behavior whilst embodied determines the soul's condition for eternity.

    Tabletop Games 
  • Dungeons & Dragons: Played straight with the spell Polymorph Other in the first and second editions of AD&D — aside from a chance of simply killing the target, its original personality could be subsumed by one more appropriate for the new form either instantly or over time. This is used as a plot point in the Dark Elf novel Exile, written in the second edition era, which features a sympathetic supporting character turned into monstrous form by an evil wizard and fighting a losing battle against the instincts that come with it. He dies in the end before his comrades can find another wizard to undo the spell.
  • Genius: The Transgression: Subverted. Shapeshifting yourself or others explicitly doesn't affect your mind. The example given is trying to turn a rampaging, bloodthirsty T. rex into a docile rabbit; what you get from that is a bloodthirsty rabbit. However, turning someone into something that isn't alive will cause them to lose consciousness until they're reverted. If you really want this to apply, you need to use a powerful mind control device alongside your transforming device.
  • In GURPS: Magic shapeshifting slowly drains the IQ stat. If it drops to five (animal level) the transformation becomes permanent.
  • In Mage: The Ascension mages can shapeshift using the sphere of Life. However, if you do not have Mind magic, or the highest rank of Life magic, you eventually take on the mind of whatever form you have shifted into. You can also leave out the Mind magic and force others to change shape causing your enemy's intellect and self image to slowly melt away over the course of weeks to be replaced by an animal's.
  • In FreeMarket, this is given as the justification for why you have to play some sort of human — albeit potentially a significantly modified one — rather than a catgirl, a total conversion cyborg, or a robot with a human mind uploaded — putting a human mind in an inhuman body causes the mind to become inhuman — or, in more plain terms, the person goes insane.
  • Warhammer 40,000:
    • The pilot of a Titan, called a Princeps, must psychically dominate the much greater and more powerful mind and spirit of the Titan. Even if this works, which is by no means guaranteed, the Princeps becomes addicted to being attached to their Titan, as they become accustomed to being the much larger and more powerful being and find it very hard to return to a human mindframe. The powerful mind of the Titan will eventually consume the Princeps', whereupon the minds fuse and the Princeps would die if detached. To plan for this, the Princeps is sometimes hard-wired to the Titan to start with. This will happen automatically if the Titan falls to Chaos, and the Princeps is then merged physically as well as mentally.
    • This idea is explored again with the Hellbrute, which was originally a mech-like machine called a Dreadnought that allows for a near-dead Space Marine to keep fighting, but has been possessed by a Daemon and has a Chaos Space Marine in it instead. The machine starts to gain its own intelligence as the Daemon takes over it, and the Chaos Marine's mind begins to fuse with the Daemon, eventually turning the Daemon, Marine and machine into a single more or less mentally cohesive amalgam. This is actually a mercy for the Chaos Marine, as the previous concept of the Chaos Dreadnought did not have the Daemon in it, and the Chaos Marine, stuck inside a robotic shell with no sensory input, inevitably went mad.
  • The player characters of Changeling: The Lost escaped Fae torturers mostly intact. They're still humanoid mortals who have free will, but Fae magic has marked their body and soul. Beast changelings still have human intelligence, but they will always be slower in using it. A Flowering may distinctly remember and fear being pruned, even though their body isn't a true plant anymore.

    Video Games 
  • Paper Mario: The Origami King: The Toads who were folded into animal shapes gained a full set of animal instincts while in those forms — including against their wishes in some occasions, as noted by a Toad-turned-cicada who notes that he was being driven crazy by the noise he felt compelled to constantly make and by a number of others who note they wouldn't have fled from Mario's attempts to rescue them but did so because their animals forms were skittish by nature. Notably, several retain animal mannerisms after being unfolded, such as former Toad-turned-dog who barks and growls in his speech and several former Toads-turned-butterflies who keep running around while flapping their hands.
  • Pokémon:
    • In the universe of Pokémon Mystery Dungeon, it's implied that this can happen when Pokémon evolve. In particular, a Lombre is unsure whether or not he wants to evolve into a Ludicolo, because Ludicolo are carefree Pokémon and he isn't sure if he wants to be carefree.
    • Also in the same game, there are multiple implications that not only did the Player Character's body became that of a Pokémon's, their "thoughts and feelings" became more like one's as well. It comes to a point when they are introduced to their rescue team base, and the player is suddenly very happy with it. They even contemplate whether their feelings are truly their own thoughts or simply a "side-effect" from becoming a Pokémon.
      Hero: Wow! I can't explain, but I'm happy! I'm a human being, but I like this place. I feel weirdly happy! It might be an instinct thing for Pokémon... Maybe this is what it feels like to want to wag your tail... It doesn't matter! I'm happy! Maybe I feel that way because I'm <Pokémon>!
    • This carried over into the anime as well.
      • Notably, Ash's reliable and obedient Charmander evolved into grumpy and unresponsive Charmeleon, who further evolved into an even more disobedient and aggressive Charizard. This is supposed to reflect how, in the video games, a trainer can't fully control a traded Pokemon whose level is higher than the badge allows. For example, you can have a level 50 Charizard, but unless you get all the badges, it won't always listen to you. Charmander was, technically, a traded Pokemon. Although Charizard never followed his orders until Ash stayed up rubbing his hands raw to defrost Charizard after it was encased in ice.
      • Dawn's Swinub/Piloswine/Mamoswine act exactly like Ash's Charmander/Charmeleon/Charizard, except it retains its obsession with Poffins.
  • A possession example: In the video game Geist, you can inhabit the body of various mice. While you retain control during those sections, your body is inherently attracted to the cheese in the nearby mousetraps, often to the point of affecting or overriding your control. Also, the body's own preferences can prevent the player from going places. When the player possesses a woman in the shower, she refuses to exit into the hallway (guarded by a male soldier) until she puts on her clothes. And after the player attacks an engineer with a pair of robotic arms to scare him, he'll never go near them again.
  • In Metroid Prime 3: Corruption, the cyborg hunter Ghor is quiet and unassuming — until he plugs into his large mecha/Powered Armor hybrid, instantly becoming gruff and hyperaggressive.
  • The reason given in Eternal Darkness for why Chattur'gha trumps Xel'lotath. (Necessary, since using the mind-over-matter philosophy would break the Elemental Rock-Paper-Scissors.)
  • In Sanitarium, the main character involuntarily changes forms throughout the game. Each form has a distinct personality, their own unique (fake) memories, and their own voice actor. Near the end of the game, he gains control over these transformations. During his first few voluntary shifts, he frantically reminds himself who he really if afraid one of the other personalities will take over.
  • In Dragon Age: Origins, the aptly named Mouse is a Mage Apprentice who shapeshifted into a mouse and can't change back in the Mage Origin. He actually talks about how his shape is well suited to hiding and sneaking and that's most of what he does nowadays as the reason why he can't change back. Subverted, as this happens in the Fade (i.e. the dream world) and he's not actually a human, but a disguised Pride demon trying to trick you.
  • Kemono Friends:
    • Animals from all around the world gathered in a giant park are turned into human-like girls due to a mysterious substance known as Sand Star. They all acquire human-like intelligence and although keep some characteristics tied to their original species, generally are mostly human-like in behavior, some of them even getting into hobbies like reading, watching TV and playing video games.
    • In the Sgt. Frog collaboration event, the 5 aliens invaders from Sgt. Frog are turned into human-like girls too due to the Sand Star. Their personality quickly adjusts to match their new bodies. All of them soon identify as girls, although Giroro initially attempts to deny it, wear female clothing without issue, and in Giroro's and Dororo's cases there's even a complete change of their speech style. Although they initially set out to go back to normal, by the end they indefinitely delay that in order to help the game's protagonists in their quest.
  • King's Quest:
    • Played with in The Kings Quest Companion chapter for King's Quest III. The cat cookie spell eventually robs the sapience from the person afflicted with it, trapping them in a feline's body forever. Yes, it is a Fate Worse than Death, but considering Manannan inflicted it on his enemies several times and was going to kill Alexander as soon as his usefulness was up, this makes it closer to Hoist by His Own Petard. In King's Quest V, which takes place several years later, Manannan is still sapient and capable of human speech, but then again he dies by being trapped in a burlap sack, because he wanted to eat a dead fish.
    • In the third chapter of King's Quest VII, there is a lord who has been turned into a stag, and he says that the longer he is forced to stay in that form, the harder it becomes for him to use rational thought, and implores the protagonist to help remove the curse on the forest before he forgets himself completely.
  • Commonly theorized to be involved in Final Fantasy VII with Sephiroth. After he manages to turn the tables and take control of the Eldritch Abomination that was trying to Grand Theft Me him, he develops a sudden interest in devouring the Lifestream. The theory is, that's just how Jenova's hunger instincts work.
  • In Kingdom Hearts: Birth by Sleep, Xehanort's entire fighting style changes when he body-jacks Terra, exclusively using all his victim's best moves — with the eventual addition of the Guardian Heartless.
  • In Portal 2, GLaDOS's body has some built-in functions that affect any artificial intelligence connected to it. The helpful but stupid Wheatley is corrupted by the body to become evil and obsessed with testing and he is quickly overwhelmed by how much power he has. Though later, this is also revealed as a function of the body — to ensure that cores would be convinced to keep testing. He's still rock-stupid though.
  • In the first Ratchet And Clank game it doesn't matter what enemies are doing prior to being hit with the Morph-O-Ray; after it's turned them into chickens they just go about their chickeny lives.
  • In Kid Icarus: Uprising, when Pit is temporarily in control of a dog's body, he's drawn to the food garbage in the street. This results in him automatically walking away from where you need to go, and the player has to fight with the controls. When you're in control of a human, however, Pit doesn't take on any aspects of their personality.
  • Resident Evil: The Darkside Chronicles: Played with when Manuela's mother mutates into a giant, feral fish/lizard monster and it turns out that her love for her daughter is the only spark of humanity left within her.
  • Two characters in Digimon Story: Cyber Sleuth are comatose humans possessed by Digimon with their personalities being amalgamations of the two individuals. For example, Kyoko's penchant for weird coffee additives like oyster sauce and mayonnaise comes from Alphamon not knowing what's normally added to coffee.
  • Purah from The Legend of Zelda: Breath of the Wild plays with it and subverts this. Originally a 100+-year-old, she uses an experimental rejuvenation process on herself that leaves her physically a six-year-old, with the requisite childish personality. However, comments from other townspeople as well as her own appeareance in the prequel reveals that she always had that personality to begin with, even as an adult. On the other hand, reading her diary reveals that, as she was passing down through her teenage years, she briefly exhibited a rebellious and resentful personality and a penchant for "teen" slang.
  • Although it only sort-of involves shapeshifting, this trope is present in Starsiege. When humans undergo the "Methuselah Process", their squishy brain is replaced with a cybernetic one, preserving their personality and memories. That cybernetic brain can later be transferred to a new body. However, transferring bodies often results in "Cell-Memory Drift", where the personality stored in the cybernetic brain is influenced by the personality of the new body's former owner. This is why when the cybernetic brain of Victor Petresun was implanted in the body of young Harabec Weathers, Victor so strongly embraced the identity of Harabec. It's also why Emperor Solomon Petresun never changed bodies, preferring to keep his original body on life support long past its normal expiration date.
  • In AI: The Somnium Files, this is part of Saito Sejima's motivation for his crimes: he was born with a brain defect that made him unable to feel positive emotions normally, but gave him an immense rush of pleasure every time he took a life. At one point, he used a Psync machine to perform a Body Surf, but this left him stranded in a body that has a "normal" brain, letting him experience the full spectrum of emotions but also depriving him of the joy of killing. Since he'd become addicted to murder at this point, he absolutely hated this, so one of his goals is to swap back into his original body so he can fully appreciate killing people once again. As for the current owner of Saito's brain, Kaname Date is kept in line by regular doses of synthetic oxytocin which compensate for its deficiency and allow him to be a functional human being.

    Visual Novels 
  • Somewhat present in Ever17. While possessing Hokuto, Blick Winkel essentially thinks he is Hokuto. Blick Winkel's discovery of his own existence becomes a major plot point.

  • In Gunnerkrigg Court:
    • Reynardine mentions the trope when Kat observes that his personality is more pleasant when he's in his wolf form than when he's a pint-sized plushy. It turns out to be an Inverted Trope: he changes form based on how he's feeling.
    • Alistair is permanently turned into a bird, with "a bird's brain and all that entails." Word of God clarifies that the personality remains the same, but behaviour is affected by the body — though the presence of sapient pigeons in the setting muddies the waters.
    • Coyote once tells a story of the time he spent an extended period of time as a dead goose in a bush by a lake (that's all three things at once, by the way) because he forgot who he really was in that form.
    • Loup in the guise of Jerrek has an internal monologue that suggests that the assumed personality is becoming less fake as time goes on.
  • In El Goonish Shive, transformations tend to influence the transformee's behavior somewhat, usually in subtle things like body language (for example, someone turned into a cat-person might find themselves purring without realizing it), and the author has said he enjoys adding goofy little quirks like that: for example he finds it especially funny when Elliot gets genderbent and then acts in a girly way without realizing it.
  • Ash in Misfile has gone under some relatively minor behavioral changes after being turned into a girl, however, unless s/he's having a period, it's nearly impossible to tell which of the differences are biological and which are due to circumstances. At one time Emily wondered whether differences in male and female brains might be responsible for Ash's poor math skills (it wasn't, as Ash sucked at math both before and after the change). That said, Ash's personality hasn't changed that much, so this is largely subverted.
  • The Dragon Doctors: Four of the five main characters suffer a bit of this as a result of getting gender-swapped.
  • Cole in CharCole tends to surrender to his Charmander instincts whenever he's in mortal danger, and sometimes needs to be snapped out of it by force.
  • Ozy and Millie presents Pirate Captain Locke, who comes from a world where people are born adults and age backwards. Locke became accordingly less mature as he de-aged.
  • Bec Noir in Homestuck is beholden to Becquerel's canine desires. He also seems to have acquired Bec's Undying Loyalty to Jade.
  • Eerie Cuties:
    • After a "Freaky Friday" Flip chocolate craving cute-vampire Nina, and standard vampire Layla find their normal cravings and personalities switching to suit their new bodies.
    • Subverted with Ace after a Gender Bender transformation. She just likes to pretend it is this trope, much to the disgust of those around her. However, the Gender Bender curse seems to affect the victim's mind based on how masculine they were before the curse. Ace found himself attracted in men and interested in dresses. When the curse transfers to Kade, he becomes a very willing magnet to many a guy.
  • In Prezleek Comics, shapeshifting elf Helwyr turns into his wolf-monster form, only for Prez to subdue him with belly rubs like a dog. Then he turns back.

    Web Original 
  • In the Whateley Universe, most of the main characters underwent Gender benders when their powers manifested; apparently turning a happy boy into a girl doesn't cause gender identity disorder and since the Unfortunate Implications are glossed over (they get therapy, but it's off screen) to the point you'd rarely realize they hadn't been a girl all their life.
    • Varies from person to person, some change form without any mental effects, some had GID before the change, and its mentioned in passing that some people have developed GID after flipping genders.
    • Main protagonists Team Kimba right now have 7 characters: two had GID before they became mutants; two have spirits (or something more powerful) riding along helping them acclimatize; one seems to just magically be happy going from girl to boy; and two are massively pissed and unhappy about being shifted.
    • It's also been known to affect voluntary shape-shifters, to the point they have classes on maintaining an identity.
    • Its actually specifically mentioned in a few of the original stories (such as Fey 1) that being an Exemplar (Mutant with Most Common Superpower as an actual power) specifically invokes this trope. That is to say that as a rule, if you are shape-changing due to being an Exemplar, eventually you'll get used to your new body — no matter if it's female, a mutant T-Rex, or a giant piece of sentient coral. The fact that BITs are generally based on the Exemplar's subconscious idea of a perfect body also helps.
    • Present in another capacity with regards to the J-Team, though it's possible that it's just Jade's flair for the dramatic showing through. Whenever she creates another instance of her consciousness to possess something, it acts more or less how you would expect a sentient version of that thing to act. The best example here is probably Shroud/Jinn, who acts a lot more mature than Jade, and pulls off a pretty convincing 17-year-old.
  • Equestrian Legends has Meadow. Formerly a pony, now a dragon, and with powerful instincts.
  • The various characters who transform in The Cartoon Man saga not only undergo physical changes, but begin acting like cartoon characters as well.
  • This short comic shows off the consequences of Ganon possessing Zelda in The Legend of Zelda: Twilight Princess.
  • You Have Become Your Avatar: Some users fall victim to their Avatars' canon personalities and attempt to act them out. Ichigo Pocky Chama got trapped in the body of Deidara and immediately got the desire to blow things up for the hell of it.
  • In My Little Pony: Totally Legit Recap, Twilight's sudden infatuation with a guy she barely knows, is explained as her being in the hormonal body of a teenager in an (in the creator's opinion) Anime esque world is affecting her so much, she has to consciously fight her desires not to just bone him on the spot. She fails.

    Western Animation 
  • Batman: The Brave and the Bold: De-aging to a toddler doesn't reduce Batman's intelligence, but it does alter his behaviour — forcing him to communicate mainly in baby-talk and draw using crayons. At the end, he's able to figure out a cure for his deaging, but has to tell the Marvel family with incoherent baby noises and pointing at things.
  • In Beast Wars, a Maximal or Predacon that acquires an organic alt mode also acquires the instincts of the organism they scanned; normally, these instincts are separated from the rest of their memory by mental firewalls, but various disruptions to those firewalls (from damage to the protoform before scanning or staying in alt mode for too long) can cause the instincts to overpower the Transformer's personality to varying degrees, though a 'bot can delete the firewalls purposely and integrate the two together without any lingering effects. Arguably, a Transformer "possessed" by their beast mode is much more dangerous, as they're forced to obey their unpredictable animal instincts instead of following typical Maximal or Predacon stereotypes (for instance, the Predacon Inferno — who had his personality almost entirely enveloped by his fire ant alt mode — became fanatically loyal to his "queen" Megatron and suicidally and recklessly effective as cannon fodder, all in line with his role as an soldier ant). Tigatron, however, manages to solve this problem on his own, simply by removing the firewalls and allowing his two halves to mesh. He later passes on the trick to the other Maximals after they're forced to remain in Beast Mode after losing their shielding system.
  • Ben 10
    • In the original series, the primary purpose of Ben's Greymatter form is to make him intelligent. Ben also says Ghostfreak made him feel weird, for a good reason.
    • In Ben 10: Alien Force, Ben's Spidermonkey form makes him more hyper and prone to making monkey-like hoots. Turning into Rath makes him quick to anger. In one episode, Big Chill turns out to be an asexually reproducer, and gives birth to alien babies after it took over Ben's mind several times in order to build a nest.
    • In Omniverse when Ben transforms into his Inkursian form Bullfrag, he suddenly finds Princess Attea, another Inkursian, very attractive.
    • In the reboot, Kevin has this problem too. As Bashmouth he often acts like a dog (i.e. chasing after sticks or being distracted by food).
  • Subverted and played in a single episode of Extreme Ghostbusters. The Monster of the Week's payload is to occupy human bodies by driving the original mind out. In the case of our Paraplegic Badass Garrett, after his body was occupied by the ghost and his mind driven out, his mind was still drawn in a (wheelchair-)sitting position, while the gang found something was amiss when the corporeal Garrett began walking...
  • Futurama: In "Teenage Mutant Leela's Hurdles", when the crew's de-aged into teenagers and then young children and babies, their behaviour changes accordingly. Farnsworth is at first unchanged because is just de-aged into his fifties, but when a botched attempt to cure himself results in him getting progressively younger, he becomes first an afroed Seventies stereotype, a hippy, a teenaged nerd and finally a Child Prodigy.
  • Kaeloo: Inverted in Episode 91. When Stumpy invokes the Personality Swap trope so he can finally be just like Mr. Cat, he gains a pair of cat-like fangs like the ones Mr. Cat has along with his personality.
  • Samurai Jack: The titular samurai is imprisoned and forced to fight in rings for entertainment twice. The first time he tries repeatedly to refuse, angrily lecturing the audience about the plot of the episode. The second time, he's in a pit with much less to prevent escape, but he's been turned into a rooster and the POV shots showing his thoughts after the transformation have tapered off. After a single attempt to escape is thwarted he just takes the role of a loyal gamecock, fighting his opponents with claws and beak, and utterly resigned when out of the pit.
  • In Teenage Mutant Ninja Turtles (2003) during the three part episode "Notes from the Underground", Foot Clan-mutated laborers grew more monstrous over time and lost their identities to madness. In one example, an apparently male character whose only name was a designation, Quarry, was originally a teenaged female named Sydney.
  • A minor version in Ultimate Spider-Man (2012), for laughs: after Mesmero causes Spiderman and Wolverine to switch bodies, Spiderman (in Wolverine) uses the "I'm the best there is at what I do" line (followed by "...and I have no idea why I said that"), whereas Wolverine (in Spiderman) realises that he talks as much about inane things as Spidey does, even when there's no one to hear him.
    Wolverine (in Spiderman): Now I'm talking about how much I'm talking!
  • Taking on the form of an animal on Wild Kratts sometimes leaves Chris and Martin overwhelmed by that animal's instincts or perspective, as when the brothers became obsessed with finding shells while using hermit crab discs.
  • Codename: Kids Next Door: When a boy is girlyfied completely, the mind will change too.
  • In Rick and Morty, one of Rick's backup plans to keep himself alive was a Body Backup Drive scheme called "Operation Phoenix" that would allow him to upload his mind into younger clones of himself. He discovers the downside to this when he uploads himself into an adolescent clone so he can hang out with his grandkids. The younger body's adolescent drives overwhelm his mind, trapping him inside "Tiny Rick". He is only able to express his plight through creative expression - for example, when "Tiny Rick" does a song and dance routine, the lyrics are actually Rick begging to be let out of the body. Rick is only able to briefly return to his old self when hearing sad Elliott Smith music reminds him that he's actually an old man. The first thing he does when he returns to his original body is to hack apart the clones with an ax.

    Real Life 
  • The changes in behavior and personality caused by anti-depressants and other psychiatric medications, lobotomies, and brain injuries attest to how changes in the brain can cause sometimes major changes in the mind. All sorts of odd quirks and personality changes caused by brain disorders that go away if those disorders are ameliorated, a nice person becoming a cranky one under the influence of stress (or other) hormones, a cheerful Genki Girl who endured tons of Break the Cutie becoming paranoid and bedridden when they get old enough for clinical depression to kick in. it's very well demonstrated that the personality is a creation of the physical structure of the brain, and even minor physical and chemical changes can turn someone into a very different person, forget turning into a different species. There's also puberty, PMS, or menopause, all of which tend to induce mood swings ranging from inconvenient to debilitating.
    • Neurological studies of patients with mental disorders show that all these conditions are associated with abnormalities in brain structure and function. The way psychiatric medicines work is by causing changes in brain function that mitigate the processes that generate the symptoms forming a certain mental disorder. It's still unknown how many of these medications precisely work, since it is very difficult to link what these medications do at the biochemical level with the mental changes they effect considering the tremendous complexity of the human brain, from the complex chemical reactions that occur in each neuron to the way the millions of neurons interact.
    • There's endless medical conditions that could cause altered mental status or psychiatric disorders, but here's a small sample of those caused by physiological disorders: there are mental disturbances secondary to hyper-or-hypothyroidism. Errors in sex hormone metabolism can change the development of the body and brain, as can production of stress hormones. Speaking of sex hormones, testosterone causes what can only be called "stereotypical maleness." Cancers can produce hormones that cause electrolyte or other imbalances that mess with the mind. Tissue changes in Diabetes I and II can cause altered mental status via hypo-or-hyper blood glucose. A stroke, injury, embolism, hemorrhage in the brain can cause all manner of terrifying neural deficits depending on the part of the brain affected. A mass effect from an tumor in the head can press on brain structures. Failures of the kidneys or livers can cause all sorts of toxic product build-up or electrolyte imbalances.
    • There's also the story of Phineas Gage, a famous person one will no doubt learn about in any Psychology 101 class, who took an iron rod to the head (warning: pic might be Nightmare Fuel). He had a significant personality change as a result, and his friends remarked that he was "no longer Gage." This case began the idea that changes to the brain's physiology will have an impact on behavior and personality. Though how much of the changed behaviour was attributable to brain injury and how much to post-traumatic stress disorder, the chronic pain he suffered afterwards and the heavy drinking Gage resorted to as a coping mechanism for both are a matter for conjecture.
    • Recreational drugs change the way your brain functions, and in doing so alter yours perceptions and behavior, which are essentially transient personality changes. For example, alcohol diminishes inhibitions and makes you do things that you would never do while sober, dopaminergic stimulants can make you manic and obsess over the most mundane things, or in high doses cause paranoia, and MDMA can make you empathic and sociable. These effects generally only last while the drug is in your system. However, when they cause long term changes and damage, the effects and the resultant alterations to your psyche, which unlike the drugs immediate effects are generally very unpleasant, are long lasting. It is why recovery from drug abuse can be so long and tortuous, and even recovered drug addicts may never return to how they once were.
  • The Proteus Effect — peoples' avatars in virtual worlds affect how they interact.
  • The physical transition period from childhood to adulthood is not an easy or pleasant one for most people.
  • This is the premise of the embodied mind thesis, which holds that all aspects cognition are influenced by bodily characteristics as innocuous as hand dominance.
  • Having one's stomach surgically reduced in size would seem like a purely physical change, the simple inability to eat as much as before. For some people that's what it works out to, with frustration resulting. For others it results in the feeling of having enough willpower to not consume as much, or just being less interested in food.
  • Sleep deprivation. Its something that everyone has experienced, and for an unfortunate many quite frequently, and even if you are not very aware on how you change when sleep deprived, you have probably seen how someone else who is sleep deprived who is usually calm or cheerful become cranky.


Video Example(s):

Alternative Title(s): The Mind Is The Plaything Of The Body


Latex Dog

Dr. K shoots the human with a transfurring dart, that turns him into a dog-person and makes him lose his mind.

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Example of:

Main / TheMindIsAPlaythingOfTheBody

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