->''This week on Creator/{{BBC}}3: When a mysterious alien force compels a beautiful woman to have sex with any male that catches her eye, Series/{{Torchwood}} investigates why this plot has appeared in every sci-fi series ever made.''
-->-- Posted on [=TrekBBS=]

One sign that someone's been possessed, cloned, body-swapped etc. is when they start behaving in a strange way romantically.

This typically means they're [[EvilIsSexy far more sexual than usual]]. Cue {{Fanservice}}.

Another variation that crops up when evil clones or evil body doubles appears is that the copy is generally a [[GoodPeopleHaveGoodSex really bad kisser]], giving a clue to their true identity.

See also ShowingOffTheNewBody. Compare GoodPeopleHaveGoodSex (because being more sexually adventurous than normal is a sign of villainy).

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!!Examples:

[[foldercontrol]]

[[folder: Anime & Manga]]
* ''MahouSenseiNegima'' has several versions of this:
** First, Negi accidentally creates a bunch of magical duplicates of himself. Naturally, they start hitting on his students.
** Later, during the Kyoto arc, the girls use a bunch of the same magical duplicates to take their places while they visit Konoka's [[BigFancyHouse temple complex]]. When they get back, the duplicates are doing a [[YoUCanLeaveYourHatOn striptease]].
** Even later, Haruna uses her artifact to make a "dark" copy of [[ShrinkingViolet Nodoka]]. Everyone notices that she's not as [[CovertPervert subtle]] as before. The real Nodoka showed up and [[ThrowTheBookAtThem hit Haruna with a book]] right before "Ero Nodoka" could also be created. Shame, really.]
** Even ''later'', she creates a duplicate of Negi for the purpose of "practice pactio kisses". Naturally, [[HilarityEnsues the results are disastrous]]. Poor Akira...
* When a vengeful spirit doll in ''[[RanmaOneHalf Ranma 1/2]]'' [[FreakyFriday trades places]] with Akane's soul [[DemonicPossession in her body]] (leaving Akane herself [[AndIMustScream trapped as a doll]]) she attempts increasingly seductive approaches to get Ranma to lower his guard... so she can kill him. All but one have [[HilarityEnsues unforseen interruptions]].
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[[folder:Comic Books]]
* Inverted by Peter Milligan's ''ComicBook/ShadeTheChangingMan'', who possessed the body of a serial killer who murdered his girlfriend's parents and ex-boyfriend. Unfortunately the body still possesses the killer's ''mind'', which is able to possess the body right back. Kathy isn't clued by Shade's performance in bed because they hadn't had sex before, but when they do, she remarks on how different and 'gentle' it is. She says, unconvincingly, "But this can still be good..."
* ''ComicBook/TeenTitans'' When Starfire was temporarily replaced by a shapeshifter from an alternate universe ([[RetCon or so she was at the time]]), the shapeshifter was much more sexually aggressive than her boyfriend Nightwing was used to. Nightwing didn't suspect anything, mostly because they'd been having problems and he was just happy that the problems seemed to have evaporated.
* ''ComicBook/{{Iznogoud}}'': A guy who can impersonate others (he changes his face whenever he puts on one of his magical masks). Subverted because the wife of the real guy actually prefers him.
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[[folder:Film -- Animated]]
* ''{{Shrek}}'': Although it never reaches a point of being sexual, Princess Fiona's reaction to Prince Charming, while he is pretending to be the yet-to-be-seen now human appearing Shrek, is constantly being off-put by his overly romantic behavior, knowing it is out of Shrek's usual character.
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[[folder:Film -- Live Action]]
* ''TheLastStarfighter''. While Alex Rogan was away from Earth, he was replaced by an android Beta Unit without the knowledge of his girlfriend Maggie. When he returns and meets her:
-->'''Alex Rogan:''' Maggie! You're never going to believe this!\\
'''Maggie:''' ''(angrily slaps him)'' I told you, Alex! Me and my, how did you put it, "strange sexual urges" aren't talking to you anymore!
* Dana when she gets possessed by Zuul in ''Film/{{Ghostbusters}}''.
* In ''Film/FaceOff'', cop Sean Archer and crook Castor Troy exchange faces and lives; they immediately go about resolving each-others' family problems in their own ways. Castor, however, uses the situation to his sexual advantage. Sean's wife, Eve, thinks his romantic behavior is odd, but doesn't see through it until the switch is actually revealed.
* When a man in the movie ''Film/{{Slither}}'' is posessed, one of the first things he does is have sex with his wife. The wife found it a little strange he was acting so horny, but just the same liked the sex, saying something to the effect "He was like a child, exploring my body for the first time."
* Gor from ''Film/TheBrainFromPlanetArous'' is a SenseFreak. One of the senses he wants to exploit is... you guessed it. His host being engaged is to him a bonus, since he can ''also'' tap into the man's feelings for his fiance. This being the fifties, she's put off by her fiance's sudden forcefulness.
* In ''Film/X2XMenUnited'', Mystique disguises herself as Jean Gray to seduce Wolverine. In addition to the changed behavior, Wolverine immediately spots the ruse because of his SuperSenses.
* In the movie ''Film/{{Dave}}'', the President's wife figures out that her husband was replaced with a double because he looked at her legs, while the actual president has long since succumbed to the Coolidge Effect. When Dave finds out she knows, his first thought is that she figured it out after seeing him in the shower.
* In the film ''Film/TheBroken'', the main character begins to suspect that something's wrong with her boyfriend when he's unusually aggressive in bed. The sight of his scary orgasm face will haunt you forever.
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[[folder:Literature]]
* In Jewish folklore, one story tells of the demon king, Asmodeus impersonating King Solomon. While in this guise, he propositions all of Solomon's many wives (and in some tellings succeeds in sleeping with all of them). The first clue to him not being the real Solomon, is that he approaches them when they were menstruating, a major taboo. His impersonation is revealed when he tries to seduce "his" [[OedipusComplex mother]], Bathsheba.
* In ''Literature/JourneyToTheWest'' the king of Wuji was killed and [[FakeKing replaced]] by a [[VoluntaryShapeshifting shapeshifting demon]]. It was a perfect imitation, except he never slept with any of his wives or concubines, which eventually contributed to his being found out.
* Inverted in one of Creator/RoaldDahl's adult stories, where the ManipulativeBastard narrator manages to convince his neighbor to swap wives for a night (the neighbor ends up thinking it was his own idea). He doesn't care what his wife feels, as they abandoned sex a long time ago as she's apparently incapable of achieving orgasm, but has an unhealthy obsession with the neighbor's wife. The plan goes off without a hitch, but in the morning the narrator notices his wife is happier than she's been in years, and that's due to [[GoodAdulteryBadAdultery the great and above all different sex they had last night]]. What the neighbor's wife thinks we don't know, but it's implied this trope is played straight.
* In Daphne du Maurier's novel ''The Scapegoat'', two {{Identical Stranger}}s switch identities. One of them goes to bed with the other's mistress. She later tells him that she couldn't tell he wasn't her lover by look or voice, but "A woman would have to be a great fool not to distinguish between one man and another, making love." She didn't say anything about it at the time, though, because she liked the new guy (he's nice). Ultimately she decided that it was the original guy she was in love with and stuck with him.
* In Parke Godwin's Hugo-nominated story "The Fire When It Comes" (title story of the collection of the same name), the existence of the ghost is revealed when she takes over the body of the (sexually repressed) wife during sex.
* Subverted in RobertSheckley's ''Immortality, Inc.'' The protagonist is in the body of another man (quite legally -- long story) and is afraid that lingering traces of that man's personality are taking over his own. When he meets the ex-girlfriend of that man, they have sex, and the protagonist is disturbed by his unusually rough behaviour. Subversion comes then [[spoiler:in the morning the woman says that the previous owner of the body used to be very gentle in bed.]]
* In the second book of ''Literature/CodexAlera'', Max has temporarily replaced the incapacitated First Lord and(ends up seducing the First Lady. He doesn't get caught, though Sextus does have words with Max about that when he recovers.
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[[folder:Live Action TV]]
* In ''Series/MyOwnWorstEnemy'', sex machine Edward makes love with alter ego Henry's wife. He's much better in bed than Henry is, leading to an affectionate Angie in the morning.
* ''Series/{{Smallville}}''
** When Lana becomes a vampire, this happens.
** This happens every other episode on ''Smallville''.
** Bizarro acts this way when he steals Clark's identity. Clark is pissed when he comes back and finds that no one, except Chloe, noticed anything suspicious. This is rather odd, because Clark hadn't been able to sleep with her because of his superpowers. One would think Lana would have noticed this, unless she just didn't care...
* When Faith ends up in Buffy's body in ''Series/BuffyTheVampireSlayer'', she sexually taunts Spike and then aggressively seduces Riley. And then has the trope turn around and backfire on her when he tries to actually make love with her instead of just getting freaky; the intimacy of the act is too much for her to handle and she flips out.
* ''TheTenthKingdom''. Virginia is so mesmerized by the addictive invisibility shoes that she almost seems willing to seduce Wolf to get them.
* In the ''Series/StargateSG1'' episode "The Broca Divide", O'Neill realises that Carter has been infected when she [[strike: tries to seduce him]] jumps him in the locker room.
* In the ''Series/StargateAtlantis'' episode "Identity", Dr. Keller gets inadvertently body-swapped with an evil AdventurerArchaeologist. The latter in the former's body (as a visual cue, the scenes have the latter's actress in, although it's clearly implied that the former is the one everyone is seeing) boards a jumper and proposes clearly to Rodney that they go to the mainland for al fresco sex, which isn't Jennifer at all. It might just be the real Keller being much less forward than the impostor was. She heavily implied that she wanted to go out with Rodney, just not that suddenly, or obviously, implying wanting to go to the mainland at the end of the episode.
* In ''Series/{{Alias}}'', it's implied a woman realises her boyfriend is actually someone else who has been genetically altered to look like him as he acts differently in bed.
* ''Series/TheXFiles''
** In the episode "Dreamland", Mulder gets body-swapped with [[TheMenInBlack an Area 51 agent]]. One of the behavior changes that convinces Scully that something is seriously wrong is that "Mulder" starts coming on to her. She [[ChainedToABed exploits this]] to force him to cooperate in putting things right.
** Same thing happens in "Small Potatoes," where the shapeshifting suspect traps Mulder in a basement and takes his form. In this case, though, while Scully suspects something's up, she goes along with the seduction until Mulder shows up and [[SpotTheImpostor faces down the shapeshifter]]. Scully's shocked reaction on seeing the shapeshifter change back into himself could indicate she was fooled, or that it was the changing itself that startled her. Plus Mulder is somewhat miffed that the shapeshifter got further with Scully than he ever did (at that point in the series).
* In ''Series/{{Farscape}}'' episode 'John Quixote' there was a sweeter version where John realised that what was happening wasn't real when the fake Aeryn told him they should leave together and abandon everyone else. "Listen - John - I came back for you. Nothing else matters. I just - want to be with you." "''Something's wrong''."
* ''Series/{{Heroes}}'':
** Matt Parkman's body is taken over by Sylar, who promptly uses it to seduce/rape Matt's wife. She loves it (or Sylar used Matt's powers to force her to). An earlier, non-sexual example is when Sylar uses his shapeshifting powers to impersonate Sandra Bennett and file for divorce with Noah.
** Parkman himself used his mind reading powers to set up the perfect date with his wife earlier in the series.
* In the ''Series/StarTrekTheOriginalSeries'' episode ''The Enemy Within'', one of the first things Kirk's "evil" half does is try to rape Yeoman Rand.
* ''Series/StarTrekEnterprise''. In "The Crossing" non-corporeal aliens take over various crewmembers, and stuck-up Brit Malcolm Reed starts hitting on T'Pol in a sinister manner.
* ''Series/StarTrekTheNextGeneration'':
** There was an episode where Troi is being tricked into telepathically taking on all the negative emotions and turmoil of her new romantic interest. One of the manifestations of this condition involved seducing and then casting aside a young crewman (much to Riker's dismay).
** Another example kicked off the series-spanning running gag of Troi's mother aggressively pursuing a mate. Of course, for Betazed women this perfectly natural: their sex-drive is known to double (or even quadruple) when they reach a "mature" age.
* Lwaxana Troi's second guest appearance on ''Series/StarTrekDeepSpaceNine'' involved an unusual complication of this normal condition when she started "infecting" people around her with her own amorous mood. The result was an episode that launched a thousand 'ships, as any character with even a latent attraction to another suddenly had their libido kicked into overdrive. Specifically: Bariel (who was dating Kira) pursuing Dax, Dax pursuing Sisko, Jake pursuing Kira, Kira and Bashir pursuing each other (including a heavy make-out session where they desperately beg to pulled apart before they have sex), and Quark pursuing Keiko. All while Odo tries to fend off Lwaxana Troi's advances.
* The one where Tasha Yar is infected by some sort of hedonistic virus which leads her to experiment on whether the android Data is "fully functional". (He is.)
-->Data? This ''never happened!''
* ''Series/{{House}}'':
** In a non-supernatural/science fictional example, House has one of his clinic patients develop hypersexuality. Played realistically straight in that he warns a family member that the 80+ year old woman in question has had a sudden, unexplained change in behavior and needs to be examined. Good thing, too, because it turns out she has [[spoiler:syphilis.]]
** There's also the early season episode where Cameron was exposed to blood from an HIV+ patient and is awaiting results from her blood test. She shows up at Chase's place and seduces him (hopefully they at least used protection). Turns out the fear and stress prompted her to take some Ecstasy and try to live it up a bit.
* ''Series/{{Fringe}}'': Alternate universe Olivia smooches Peter so he won't see the blood trickling across the floor from the murdered man in the bathroom.
* ''Series/DoctorWho'': When Rose Tyler gets possessed by Lady Cassandra, she surprises the Doctor with a sudden kiss, likely a result of being suddenly dumped into a body full of teenage hormones. Hilariously, the Doctor's first reaction isn't "something is really wrong here", but "Yep...still got it."
* In ''Series/BarneyMiller'' a woman comes in to the police station because she thinks her husband of 25 years is a replacement body, essentially because all of a sudden he did things to her he's never done before. One of the police officers taking her report, pretending to take her seriously, and doing a ShoutOut to ''InvasionOfTheBodySnatchers'', asks her, "Did you check for pods?" It turned out her husband had done some reading and discovered women love oral sex. He had never had any idea, and did it for her for the first time in her life.
* An episode of the 1995 ''Series/TheOuterLimits'' featured Alyssa Milano as a pure, virginal teenage girl...who is possessed by an alien entity that feeds by seducing and devouring men.
* And ''Series/{{Torchwood}}'' used the same plot in its second episode. The alien in that case was using 'orgasmic energy' as a FantasticDrug.
* In ''OrphanBlack'', Paul begins to suspect that something is up with his girlfriend [[spoiler: and test subject]] Beth when she starts acting very sexually aggressive. In reality, Beth committed suicide in the first episode and her clone Sarah stole her identity.
[[/folder]]

[[folder:Video Games]]
* Meryl in ''VideoGame/MetalGearSolid''.
* Subverted in ''EatLeadTheReturnOfMattHazard'', Matt Hazard, a sentient, videogame character, is helped in his fight for survival by mousy female programmer named QA, whose ingame avatar is colored blue. She berates Matt for both his old one-liners and for hitting on her. Later, QA reappears colored red, and comparatively sassy. After a few mess-ups, blue QA finally reappears, and red QA tells Matt he has to figure which one is real. Matt, being experienced with several game genres and is, by consequence, incredbly genre-savvy, makes a comment to red QA to the effect "Oh come on. I knew you were the evil twin a long time ago."
[[/folder]]

[[folder:Webcomics]]
* In ''Webcomic/ItsWalky'', Joyce's "evil" clone is easily identified by the fact that she merrily seduces whichever parts of the male cast is available (the resident JerkAss, as it turns out). Joyce's response... ain't pretty. Or surviveable.
* The usual variant is inverted in the BL comic 'Webcomic/{{Paradox}},' when Tommy is possessed by a soul-eating demon. Dake realises something is off because Tommy's reaction to an offer of sex is 'maybe later,' after he'd been trying to get into Dake's pants for the last couple of chapters.
* In ''Webcomic/TheOrderOfTheStick'', the evil twin variant is used when Elan, a good-natured naive bard is [[spoiler: framed and swapped with his evil twin brother Nale, who proceeds to attempt to woo Haley, with aims to murder her at the height of passion, since she, up to this point, had a hidden crush on Elan.]] Haley notices the startling change in behavior, including the initiative he takes in arranging a romantic date, but ignores her instincts (and that of her inner personalities).
[[/folder]]

[[folder:Western Animation]]
* In the infamous ''WesternAnimation/JusticeLeague Unlimited'' episode "The Great Brain Robbery", a notable scene occurs where Tala seduces Lex Luthor, not knowing that he's recently switched bodies with The Flash. After the situation is reversed, Tala is actually ''disappointed''. Her exact words were that she wasn't used to him being so "gentle", "caring" or "enthusiastic."
* ''Series/TheSimpsons'':
** When Homer Simpson was kidnapped and replaced by [[HughMann a lookalike with an obvious German accent and no understanding of Homer's personality]] in extended {{Parody}} of ''ThePrisoner'', it's [[{{Squick}} squickily implied]] that his offer of "efficient German sex" is what keeps Marge from realizing anything is amiss for ''several months''.
** Spoofed in the parody of ''Literature/TheIslandOfDoctorMoreau'' from Treehouse of Horror XIV: Marge gets turned into [[FurryFandom a literal catwoman]] by Dr. Hibbert and gets intimate with Homer. The next morning he finally notices her change when she jumps out the window to chase a bird, remarking "I had no idea! ...Though I suspected something during the sex."
* In ''WesternAnimation/TheBoondocks'', in the episode "Stinkmeaner Strikes Back," Tom Dubois is this way with his wife Sarah, after being possessed by Stinkmeaner. Tom Dubois is noticeably much more proactive than usual with Sarah; he shouts at her "I'm going to have sex with you!" and then carries her upstairs, where they have amazing sex. The reason Sarah considers this an improvement is because, as shown in a montage in another episode, usually Tom is unskilled enough in bed that Sarah was shown reading a book as Tom finished his orgasm.
[[/folder]]

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