Not Himself

A close relative of Evil Twin and Freaky Friday Flip, Not Himself is any plot where a character acts contrary to the way they normally behave. Can be used to provide a mystery to be solved, or to incite bewilderment in the other characters. The deviation is often a marked increase in evil, insanity, and/or horniness: the emergence of the inner shadow -- or a switcheroo.

Sometimes, it's a detective or police character behaving as if they were corrupt, or a criminal. This will usually turn out to be the Fake Defector.

If the change is deliberate to save their friends, it's Something They Would Never Say.

If the change is caused by poor writing or is never given an in-canon reason, this could be Character Derailment.

Contrast with Something Only They Would Say. See also Virus Victim Symptoms.

Anime & Manga

 * Subverted in Magical Project S while Misao certainly wasn't acting like herself when she tortured the main cast as the evil magical girl Pixy Misa (she wasn't even aware of her other side) it was revealed that it was in fact herself (the repressed aspects of her personality),
 * Usagi and Mamoru in Sailor Moon most likely because the other is involved in some way.
 * Mimi in Perfect Blue throughout the majority of the movie. Also, Rumi towards the end.
 * Lelouch on occasion in Code Geass. As well as Suzaku and Rolo once he starts to become closer to Lelouch.
 * Utena after having lost a duel.
 * Shinji of Neon Genesis Evangelion many times, as well as much of the other main characters, mainly Asuka.
 * In the anime series Tsukuyomi Moon Phase, Hazuki has frequent periods of Not Himself, during which she "becomes" Miss Luna, a lustful, blood-thirsty vampire girl.
 * Aside from Ken during Digimon Adventure 02, the normally nice and affable Takeru has been known to become scarily angry when there is a threat to his Digimon and friends, as a result of witnessing the death of his own Digimon in the first series. These angry moments have caused him to physically attack the then-Digimon Kaiser Ken (while smiling in dark amusement at Ken's injury of his [Takeru's face]), advocate the killing of Dark Digimon, and deeply disturb Jogress partner Iori on separate occasions.
 * Just to put this into context, Iori is The Stoic of the series. To freak him out would seem to be a very hard task... unless Takeru's pissed.
 * This usually sparks the plots in Higurashi no Naku Koro ni, but one character stands out in particular: "The person who was there was not the Rika-chan I knew. It was another Furude Rika." Of course, the difference between Rika and the other examples is that
 * In Bleach, the 9th Espada,
 * In Dragon Ball GT, a compromised Vegeta calls Goku "Goku" rather than "Kakarot", thus giving himself away.
 * Goku and Gohan both qualify, as their Super Saiyan transformations, at least initially, radically alters their personality from the incarnation of goodness and purity to cold blooded, driven-by-rage, homicidally sadistic Blood Knights.
 * Basic corollary: The more pacifistic a Saiyan is in their base form, the more sadistic (and dangerous) they are as they increase in power. Vegeta and Gotenks barely see any change in personality in their Super Saiyan forms, while Gohan, who'd rather go to school and be normal, could give the KYUUBI a run for its money on bloodthirst when he's SSJ2.
 * Beware the Internet Backdraft when bringing this up with Mai-HiME, particularly with reference to . The anime is ambiguous about how much (if indeed at all)
 * Interestingly enough,.
 * In an episode of Natsume Yuujinchou Shi, Nyanko-sensei has to masquerade as Natsume after he's trapped in a bottle by a youkai. Nyanko-sensei then proceeds to act exactly as he usually does (read:a Jerkass), much to Natsume's dismay.
 * In one To Love Ru story, Haruna suddenly became an evil sadist, which was hilarious. It became a Funny Aneurysm Moment when the artist's wife, who Haruna's design was based on, turned out to be a crazy psychopath who kidnapped their daughter, among other demented things.
 * Played for drama toward the last chapter of the Golden Age Arc in Berserk, which concludes the prologue that dives into Guts' backstory about how he came to be the dark, brooding and vengeful man that he was introduced as in the Black Swordsman Arc. Although they were not present at the harrowing Eclipse  Godo, Rickert, and Erica noticed the dark shift in Guts' character, which not only involved the increased blood-lust in his personality, but also his dark dress and intense scowling. Even the audience can notice a clear change in Guts' appearance just chapters apart.

Comic Books

 * Cosmic Boy of DC's post-Zero Hour Legion of Super-Heroes spent a whole Arc being Not Himself and alienating his teammates at every opportunity . Some Legion fans never forgave him for it. (It didn't help that this particular arc occurred in the first couple years after a total reboot of the Legion, so it wasn't as clear as it might have been that this wasn't just Cos's new personality.)
 * Apparently, hacking into Superman's mind is like evil hypnotists' wikivandalism. Some bratty six-year-old in Minneapolis trips over a ouija board, next thing you know our Man of Steel is giving the Batman a wedgie. Supes has probably been brainwashed, hypnotized, or possessed more than any character in fiction. And if you count the times he's pretended to be Not Himself, more than all fictional characters combined. Read any random five Superman or Superman-associated comics from the 50s through the 70s, and see if you can't find one of these stories.
 * Or refer to here for the condensed version.
 * There's also the arc in 2000 where Lois and Clark's marriage appeared to start falling apart, with Lois accusing Clark of not caring about her because she was just a human, and of cheating on her with Wonder Woman, effectively turning the poor guy into a miserable wreck and culminating in her walking out on him. Turns out it was actually Parasite masquerading as Lois in order to simultaneously feed off of Superman's powers and destroy his spirit in a plot to kill him. The arc wound up with what looked like a superpowered-Lois Lane beating the snot out of Superman right in front of a flabbergasted Perry White and Jimmy Olsen, and apparently required loads of explanations from the real Lois after everything was cleared up, especially as Parasite had been running around using Lois's know-how to steal millions of dollars.
 * In the Justice League International comic, Guy Gardner spends a rather extended period like this after minor head trauma, courtesy of one punch. The abrasive, chauvinistic, arrogant Guy turns into a sweet, Sensitive Guy -- who really exists deep down, as exhibited when Guy falls in love. This trope is partially subverted, though, because the League likes him better as Sensitive Guy and therefore makes no effort to return him to his previous state.
 * Sonic The Hedgehog: After the Time Skip, Antoine inexplicably became an insufferable Jerkass. Writer Karl Bollers wanted to write this off as natural character growth, but fellow writer Ken Penders decided he didn't like that idea, so he changed to Antoine having been switched with his Evil Twin from an Alternate Universe. And about the time of that reveal, Sonic's own twin from that same AU switched places with him as well, so the other Freedom Fighters had to deal with "Sonic" acting out of character too.

Fanfic

 * My Immortal: The only reason Dumbledore swore was because he had a headache, okay? (Of course, he then swears regularly for the remainder of the "text".)

Film

 * Inverted in Dangerous Liaisons, when the Vicomte Sébastien de Valmont, known to be a ruthless, womanizing manipulator genuinely falls in love with Madame Marie de Tourvel. He is forced into the situation by Marquise Isabelle de Merteuil, and with tears in his eyes has to push away the woman he loves through cruel manipulation. She is aware that it's odd for the Vicomte to speak thus to her, but is heartbroken nonetheless.
 * In Everyone Says I Love You, one of the characters becomes a Republican to the great surprise (and dismay) of his family. It turns out it was because of some sort of brain problem.
 * Nice...
 * Quite a lot of this in Fallen: "I wanna tell you about the time I almost died...."

Literature

 * Ditzy but loyal vampire queen Betsy Taylor becomes a real bitch after reading too many pages of the Book of the Dead in a row in Undead and Unappreciated.
 * In the V. C. Andrews novel April Shadows, April's father starts to act like a Jerkass to his family for seemingly no reason.
 * This is one of the main plot points in the Animorphs series due to the fact that the primary villains are aliens who take over the bodies of humans and mimick them near perfectly.
 * In L. Jagi Lamplighter's Prospero in Hell, Miranda admits that she had not noticed that Mab had been replaced with a shapeshifter, just that he was acting oddly.
 * Marianne Dashwood in Sense and Sensibility. After she is jilted she falls into a despair and eventually after months of barely eating or sleeping she stays out for hours in a rainstorm while insufficiently wrapped up. She nearly dies of fever or has a bad flu (YMMV) but when she recovers she has suddenly gained about five years worth of emotional maturity and not long afterward marries someone much older who she was not in love with. Marianne is passionate and talented and struggles to conform to what her society expects of a young unmarried woman. It feels as though Austen is building up to tragically killing her off but at the last minute she backs off and Marianne is suddenly able to deal with the pressures of hiding her feelings in the public space.
 * Marianne Dashwood in Sense and Sensibility. After she is jilted she falls into a despair and eventually after months of barely eating or sleeping she stays out for hours in a rainstorm while insufficiently wrapped up. She nearly dies of fever or has a bad flu (YMMV) but when she recovers she has suddenly gained about five years worth of emotional maturity and not long afterward marries someone much older who she was not in love with. Marianne is passionate and talented and struggles to conform to what her society expects of a young unmarried woman. It feels as though Austen is building up to tragically killing her off but at the last minute she backs off and Marianne is suddenly able to deal with the pressures of hiding her feelings in the public space.

Live Action TV
"Chuck:"
 * In Chuck, the penultimate episode sees Chuck realizing that something is deeply wrong when a . He convinces himself that it's just the result of, but he can't explain.


 * In the second season of Angel, Angel turns on his friends and finds himself without hope.
 * Not to mention his role in the second season of Buffy, after experiencing a moment of pure happiness (ie sex) with Buffy caused him to lose his soul.
 * Or you could say that almost the entire runs of Buffy and Angel are Angelus being Not Himself.
 * Spike and Dru certainly thought so. Less clear what Darla thought.
 * Say it with me now. Buffy.
 * Twin Peaks ended with a Not Himself, presumably to have been the plot of the cancelled third season. "How's Annie? How's Annie? How's Annie?!"
 * Star Trek has several, mostly involving Kirk and Picard.
 * Data is pretty good at them, too. Usually when he's possessed by one thing or another, or something's going weird in his programming.
 * Geordi LaForge gets one of these in the episode The Mind's Eye. The most disturbing thing about it being that asides from his being brainwashed and attempting to murder someone in full view, he behaves entirely and utterly like himself.
 * Star Trek: The Next Generation basically has three plots: (1) The Enterprise suffers engine failure leading to an hour of Techno Babble, (2) The holodeck tries to kill everybody, or (3) one or more of the crew members get their minds taken over by aliens. All of the episodes in the 3rd category are examples of this trope.
 * In the Star Trek: The Original Series episode Amok Time, Spock's uncharacteristic emotional outbursts are the first clue that something is seriously wrong with him.
 * Used regularly in Farscape. On one occasion it becomes clear that it's not really Aeryn when she doesn't know, once when she suggests abandoning their friends, and once when she's suspiciously happy: 'Aeryn smiling for no reason. That ought to have been our first clue.'
 * Perhaps the most famous example of this trope, though, is when Harvey takes over Crichton at the end of Season 2 and.
 * Smallville has its fair share of Not Himself episodes, no thanks to Red Kryptonite and the truly absurd number of villains who have possession abilities.
 * The Office, American version: assistant manager (or assistant to the manager) Dwight Schrute, a pompous, anti-social jerk, inexplicably starts acting nice to everyone. Later it is discovered to be the effect of a concussion Dwight suffered as a result of a car crash earlier in the episode.
 * In Babylon 5, Michael Garibaldi spends most of season 4 acting strange and distancing himself from the rest of the crew. It turns out.
 * Interestingly, it's revealed that his personality wasn't actually altered. Instead, the darker aspects of his personality were intensified, making him even more paranoid and suspicious of authority than normal.
 * News Radio: Matthew punched out Bill after one of Bill's pranks went too far. Somehow, the two switch personalities - Bill becomes submissive, while Matthew starts acting like the office alpha male. An accidental slap from Bill reverses the effect, and the two return to normal.
 * In a later episode, Matthew suffers a mid-life crisis after turning 30 and starts acting like a '70s-era British punk.
 * On an episode of Kojak, Lt. Kojak appears to go corrupt, but of course in the end it's all a big undercover operation.
 * Used to the point of exhaustion on Knight Rider, where at least twice a season someone would screw with KITT or manipulate Michael for various reasons.
 * Get Smart: Maxwell Smart is attempting to infiltrate a KAOS group, and as such needs to dramatically burn all his bridges with CONTROL. Of course, this being Get Smart, it doesn't work quite as planned.
 * Happens a lot in Stargate SG-1. Between the Goa'uld, mind control, robots, clones, and other random behavior changes, the characters get a pretty good taste of this.
 * They get pretty good at spotting it too; in fact, standard SG training involves numerous scenarios that involve teammates possibly being compromised by a Goa'uld.
 * In season 5 of Lost, after Locke is not himself, acting more determined and secretive than ever and knowing things he can't possibly know. Because
 * This happens to almost every member of Torchwood in the Torchwood episode "Adam." Especially Owen.
 * This happens twice in The X-Files, once in "Small Potatos" that involved a shape-shifting man, and another in "Dreamland", where Mulder switches bodies with an Area 51 worker. Both Non-Mulders try their hand at seducing Scully.
 * Anytime an angel or demon appears on Supernatural could count as this since both angels and demons must possess a human host in order to operate on Earth. Most of the human hosts never appear onscreen without being possessed by the angel/demon, but they obviously wouldn't have their angelic/demonic powers when they're not being possessed.
 * Duncan under the Dark Quickening in Highlander the Series

Toys

 * Hafu starts to notice that Lewa is behaving strangely at one point in Bionicle. This was the result of Lewa having his body stolen by Tren Krom via a Freaky Friday Flip. The real Lewa was stranded several hundred miles away in the body of an Eldritch Abomination which was fused to an island.

Video Games

 * in Final Fantasy IX displays this for a short while near the end of the game. Given his normally cheerful personality, this moment is notable as it hints at.
 * A good chunk of the game's first half is driven by Princess Garnet wanting to find out why her mother was not acting like herself. Turns out she was being influenced by Kuja.
 * In Final Fantasy IV, it is said at the beginning of the game that the King's behavior changed. Of course...
 * HK-47 can have a Not Himself moment in the second game if the player installs a Pacifist Package into him. Needless to say, this genuinely scares the hell out of him.
 * In The Legend of Zelda: Majora's Mask, one of the sidequests you need to complete for One Hundred Percent Completion is helping a little girl, Romani, with defending the ranch's cows from aliens on the night of the first day. If you fail, the aliens abduct the cows and Romani, since she was also in the barn. They bring her back on the third day--but she can't think straight, doesn't recognize Link, and shakes her head, trying to remember or forget things. It's assumed by the whole fandom that she was lobotomized.
 * Video games in general bring a unique version of this where the out of character behavior is caused by the player controlling the action either being a jerk or having a sense of humor toward the choices the game throws at him.
 * Final Fantasy Tactics, in an early mission, you find a man being menaced by bad guys. You have a choice to either prioritize beating up the bad guys, or saving their victim. Choosing the former prompts the main character's best friend to ask if he's flipped his lid.
 * Super Paper Mario, there's a funny mini-game where you play as Peach trapped in a dating sim and can choose her reactions to the other character's fumbling attempts to court her. You can of course choose to have her react favorably... An interesting case in that doing this repeatedly will cause the princess to call -herself- on her bizarre behavior.
 * Super Paper Mario, there's a funny mini-game where you play as Peach trapped in a dating sim and can choose her reactions to the other character's fumbling attempts to court her. You can of course choose to have her react favorably... An interesting case in that doing this repeatedly will cause the princess to call -herself- on her bizarre behavior.

Visual Novels

 * In Fate/hollow ataraxia, the fact that many of the characters are nothing like they were in Fate/stay night is actually an early clue that something's wrong with this reality besides the whole Groundhog Day Loop thing.

Web Comics

 * Parodied by Nodwick.
 * In Gunnerkrigg Court, Chapter 18, Robot S13 -- previously the comically Pollyanna Chew Toy -- abruptly begins acting deadly serious and proves to be a dashing swords-bot, much to the surprise of Annie and Kat. Presumably his new body has something to do with the change, but how remains to be seen.
 * After a trip in Zimmy's twisted mind, Jack began becoming more and more unstable. It's implied that he gets better after Zim's intervention though.
 * In Fans, when Alisin's incurable and deadly blood disease starts to kick in, she sets out to pull an April Shadows in order to leave her loving boyfriend less sad when she goes.
 * In Dead of Summer, falls under this. At first he seems normal (and awesome), though breaking a bad guy's finger may raise some eyebrows. But later on, he
 * Turns out
 * In Casey and Andy, Satan places Andy by the Soul-Keeper, an ancient and complicated machine. She was able to tell later he'd been replaced by Azrael because he hadn't started taking it apart to see how it worked.
 * It appeared this way with Varsuuvius in Order of the Stick, but accepting that it was consistent with his character was part of his Character Development. A straight and more striking example would be Belkar's very brief wisdom boost turning him repentant and pacifistic.
 * In Newshounds, Rochelle being afraid of danger instead of craving it was the first sign of.
 * In Alien Dice, Lexx has one of these events later in the comic. It's rather obvious and jarring, considering his usual "nice but distant" personality.

Western Animation
""Would you like to... Oh blast, what was it we did again? 'Play video games and rage against the machine?'" "Do we ever!""
 * A tearjerking example occurs in WALL-E:  Fortunately,.
 * Winx Club: 4Kids turned Stella being a bit bitchy with her roomies from being part of her character to being the result of a spell, thus making it funnier. (Clip) There have been a few instances that are in both versions, though.
 * Briefly in the Danny Phantom episode "The Ultimate Enemy" where Danny's evil self, Dark Danny, goes to the past (present time) and disguises as his old fourteen-year-old self. His friends wonder what's up with him when he starts speaking rather eloquently, but being a smart bastard, Dark Danny quickly fixes this and their suspects drop.


 * Danny also holds the dubious honor of at one point doing this twice at the same time. An accident splits his personality into the overly dramatic, comic style Hero Danny, and the laid back, mundane (and I quote) 'Fun Danny'. Confusion (and hilarity) briefly ensues.

Real Life
"[...]scientists have come up with all kinds of theories about the damage affecting his impulse control. But, holy crap, some of us turn into dicks after missing morning coffee. Can we not cut a guy some slack after surviving a fucking spike through the skull?"
 * Several illnesses or psychological factors can lead to a person's behavior changing dramatically. One of the most well known examples would be Phineas Gage, a railroad worker who was said to have been honest and reliable prior to an accident which lead to a metal pole being blasted through his head, damaging both his frontal lobes. Afterwards, he became a much nastier person. The accident shed light on the effects that frontal lobe damage can have on personality.
 * Maybe it wasn't the accident. In the words of the clearly well-researched website Cracked:


 * He wasn't competent to run his crew anymore. He didn't have respect anymore. Plenty to get mad about.
 * He lost hypothalamus and frontal lobe connection, meaning less stuff was routed through the frontal lobes, particularly emotion.
 * Reportedly, Gage started drinking heavily after the accident -- which could be either a direct result of brain damage, or an attempt to dull chronic pain from the injury. In either case, the new personality might be simply being a mean drunk.
 * On the other end of the brain damage spectrum, it's possible to damage the part of your mind responsible for recognizing people. Not that you'd forget who they were, mind you. You'd know who your mother is, exactly what she looks like, but your mind just won't recognize the person who acts like and looks like your mother as actually being your mother. People with this type of brain damage believe that everyone they know has been replaced with an imposter. All of a sudden, everyone else in the world is Not Him/Herself.
 * Lobotomies. Goddamn lobotomies.
 * Which starts by ramming an ice pick into your eye. Hey! Where are you going? I only got started!
 * Rosemary Kennedy (sister of former U.S. President John F. Kennedy) was having mood swings and underwent a lobotomy at age 23, which left her permanently incapacitated. After the experience her speech was unintelligible, she would stare blankly at walls for hours, and was left mentally handicapped.