There are some characters whose physical form is involuntarily dictated by their environment, or the people around them. Sometimes this is useful; perhaps the character can instantly adapt to new environments. More often, this can be a pretty serious case of Blessed with Suck: you can transform, but you'll only turn into whatever other people think of you. Which wouldn't be a bad thing if you're hanging out with your close friends, but even Cthulhu shudders to think about what will happen should you be, say, very promiscuous.
Empathic shapeshifters very often have some form of Adaptive Ability as well.
Can overlap with A Form You Are Comfortable With and You Cannot Grasp the True Form, if the taken form is merely whatever the person looking wants to see. When somebody changes in response to their own emotions, that's Living Mood Ring.
- In Osamu Tezuka's Phoenix: A Tale of the Future, the Moopies are amorphous aliens who will voluntarily become anything a person desires. Earth society condemns interacting with them, because it is of course tremendously addictive. The main character is in love with a Moopie who has turned into his idea of the perfect woman.
- In Revolutionary Girl Utena, it's heavily implied in the Black Rose Arc that "Mamiya" is really Anthy in disguise, and in fact Mamiya at first glance appears to be a Distaff Counterpart to Anthy in terms of appearance.
- Ixtli in RahXephon will take the form of the whomever the RahXephon's pilots cares about the most.
- Meggan, from the spinoff Excalibur. She is the Trope Namer as she was explicitly described as a Empathic Shapeshifter and, indeed, she would look like what other people thought she should. This caused her quite a lot of angst as a kid, though she fortunately had other powers to back it up (and by other powers we mean that she won the Superpower Lottery, big time) and had the ability to adapt to any environment bundled in. However, she managed to move past it as of the Captain Britain and MI13 series.
- Darwin from the X-Men would gain new powers to protect himself from threats, often shape shifting in the process.
- Lifeguard, also of the X-Men, teleported situationally, developing powers that would be useful to save any endangered lives around her.
- Earth X suggested that all of Marvel Comics' supers were evolving toward this state. Loss of Identity soon follows.
- Benjamin Deeds, the second character to use the name Morph, who joined Cyclops' post-Schism X-faction. His appearance would change to resemble anyone he spoke to. Anyone who didn't see it in action would instinctively like and trust him.
- Trauma of Marvel's The Initiative can touch the mind of his target and turn into their greatest fear — complete with that fear object's abilities. The shortcomings of this ability is sown in the World War Hulk storyline, when Trauma is sent to fight the Hulk, and fails because the Hulk doesn't fear anything.
- One of the stories in Demo has a girl with this kind of power, but it only applies to romantic intent. She's searching for someone who will see her the way she really is. She finds a woman who seems to be able to do just that and falls in love with her based on that fact alone, only to find out that the woman is already seeing someone (and hence implicitly didn't care about making her look like the kind of person she already had).
- One of the later arcs of W.I.T.C.H. had Cornelia befriend a girl named Leah, who had the magical ability to change her appearance depending on the current needs of those around her. However, she didn't have full control of her power, and had changed her appearance so many times that she no longer remembered what her face originally looked like. The girls were eventually able to bring her to Yan Lin, who was able to help Leah return to her true appearance.
- Green Lantern Xrill-Vrex is an empath who can key in to specific individuals around her to get a better idea of their feelings, motivations and language, and when she does so she takes on elements of their appearance, speech patterns and behavior though she usually remains more stoic and doesn't allow their feelings to dictate or change her actions. If she's keying into an individual who is humanoid and close to her size and mass she ends up looking just like them.
- Prot in K-PAX claims that he appears human on Earth because it is the most energy-efficient shape he could assume here. He uses the analogy of "Why is a soap bubble round?" and says that on K-PAX he appears K-Paxian.
- In Panna a netvor (the Czech film adaptation of Beauty and the Beast) , the beast, instead of changing completely from monster to human in a single pivotal scene like in almost every other adaptation, changes according to the beauty's perception of him: when she grabs for his talons, expecting them to be a pair of hands (as he's forbidden her from looking at him and she believes he's human), they magically transform into human hands, but it isn't until she declares that he's beautiful in her eyes that his human form is fully restored.
- "Angel Down, Sussex" revolves around a being whose appearance and behavior is influenced by the people around her. Of three investigators who get a look at her, the starry-eyed spiritist sees a fey changeling, the gleefully-depraved occultist sees a succubus which proceeds to anal-probe him, and the skeptic just sees her as a hoaxer. At the end someone wonders what she might appear as to someone decades from now.
- The Animorphs series makes it quite clear that the instincts of the animal always pop up. Not so bad if you're morphing a dolphin. You basically experience pure joy. Not so good if you're morph a prehistoric superpredator. Then you turn on your friends and attack random prey animals. Nightmare Fuel if it's some mindless automaton insect. All you can do is get in line and serve the queen.
- Isaac Asimov and Janet Asimov's The Norby Chronicles: The "All-Purpose Pet" is an animal/species created by Mentor First, from genetic samples across multiple planets. Only two are ever mentioned; the original Pet (who Fargo named Oola), and her child, which was given to Jeff. Both animals look somewhat like a cat normally, but are sensitive to the minds of those around them. The reason why they're an "All-Purpose" pet is that they adapt to be the sort of pet you'd like. If you prefer dogs, then she'll bark and turn into a beagle. If you prefer cats, then she'll purr and become a miniature simoladon. If you want a nununiy, then she'll grow sixteen legs and tentacles at each end. They'll take whatever shape you want them to, if your thoughts are strong enough.
- Mix a little of this with a whole lot of terror and you've got the insane children's book A Bad Case of Stripes. Camilla, a little girl who's self-conscious about how other people view her, wakes up one day covered in stripes and her appearance changes based on what people around her say. It enters Body Horror territory when the doctors' voiced ideas about what kind of illness she might have causes her body to develop symptoms of that illness (ex: a doctor saying she may have a virus causes virus-like extensions to sprout from her body) and a therapist's suggestion for her to relax by imagining that she's in a room causes her to merge with her room, her eyes becoming picture frames and her lips becoming her bed. Not until she learns to be herself and stop worrying about what other people may think about her weirder traits does her body return to normal.
- In Clive Barker's Imajica, one character is a "mystif" who takes on the form matching the unconscious sexual desires of whoever looks at him/her/it. The character says that many people, when shown what they actually desire instead of what they think they desire, end up feeling horrified instead of attracted.
- In James Blish's The Duplicated Man, the title duplicates are formed by a machine that is controlled telepathically by its operators. The operators are displeased to discover that all the duplicates come out wrong because each of the operators has his own imperfect, thoroughly subjective ideas of what the original guy is like, both in his personality and his appearance.
- In the Doctor Who Expanded Universe novel Silhouette, one of the "living weapons" is a shapeshifter who duplicates a person's self image, which usually gets them to to trust him. He gets very confused dealing with the Doctor, who has twelve self images, and doesn't really like any of them.
- Harry Potter: Boggarts take on the form of a character's greatest fears.
- It uses the "turn into something that someone fears" gimmick. When luring people in, it wears the form of a harmless looking clown, but it's also become various movie monsters and predatory animals depending on its present company. It uses this ability to target children, apparently because adults tend to be more afraid of non-tangible things, which are beyond its capabilities (not that the child-eating monster isn't Adult Fear already).
- In A Practical Guide To Evil: Succubi/Incubi take the form the person who summons the devil finds most attractive. Some mages summon them to learn more about themselves.
- The Warlock in Spite of Himself series has Witch-moss, an alien fungus that adapts its shape in response to Telepathy— even unconscious telepathy, explaining why there are elves and many other mythical monsters on the planet Gramarye.
- Wild Cards: Succubus becomes the ideal lover of whoever she's near, and has since childhood. Her parents actually took advantage of this and pimped her out as a prostitute (her clients were mostly unaware of her real age since she looked older even in her default form).
- Red Dwarf :
- A one-off character on looked like whoever the viewer was most attracted to — The very personification of beauty is in the eye of the beholder.
- The Psirens from a later series could take the form of their chosen victim's greatest sexual fantasy, complete with voice and mannerisms, etc, only they did it to get brains to snack on.
- The Monster of the Week in the The X-Files episode "X-Cops" hunts and kills people using the form of whatever they're mortally afraid of. Forms it's assumes include a werewolf, "the Waspman", Freddy Krueger, a crackhead, and the hanta virus. This is as much a weakness as a strength for it; it fails to kill one victim because the thing he was most afraid of was his lover leaving him, which obviously isnt fatal and has its effect ruined when said lover happens to walk in as the monster is taking his form.
- A one-shot patient in House has a bizarre type of amnesia, where he will automatically adopt the mannerisms and personality of whoever the dominant person in the room is. At one point, House and Cuddy decide to use his condition to deliberately determine who is really top dog by seeing who he will mimic in a room with just the two of them:
Patient: [to Cuddy] Your ass is amazing...
House: That's definitely me.
Cuddy: Doesn't prove anything... I'm very proud of my butt!
- An episode of Star Trek: The Next Generation featured a woman who was to be used to seal a peace treaty: she would marry the leader of a planet and end a centuries long war (which began when one royal brother kidnapped the other's bride). The problem is, while she remains physically the same, her personality changes to whatever the men around her find irresistibly attractive, which has the added effect of her being irresistibly attracted to every man she meets. At least until she reaches "maturity" and forms a bond with a single mate, then Shapeshifter Mode Lock kicks in and she remains that person's ideal personality permanently. So the problem is twofold, managing a way to safely transport her to her destination without her causing a riot among the various males who all fall in love the moment they meet her or her bonding with a single individual before she meets her arranged husband. They manage the former by keeping her as isolated as possible once they realize how disruptive her mere presence can be, the latter issue ends up as yet another example of Picard's tragic love life. She bonds with him, but of course Picard's ideal mate is noble enough to put her duty to end the war ahead of her own happiness, so she resolves to fake bonding to her new husband (using her residual empathic ability to understand his desires) for the rest of her life.
- Skenfrith, a bizarre one-off character from Fraggle Rock, is completely at the mercy of other people's opinions of him. It's really amazing how upbeat he is come to think of it.
- The Tulpas in Over the Edge are formed by what their opposite expects them to be.
- City of Heroes: This, combined with Power Perversion Potential, can be found in...certain RP cliques on one of servers.
- Eevee: every game describes it as having an unstable genetic structure, and it evolves into one of several creatures depending on environmental stimulus (or exposing it to a magical stone). So far, we have evolutions for eight habitats: hot/fire, aquatic, electrical, nocturnal, diurnal/friendship(?), forest, cold/snowy, and bonding with another being. That said, once it evolves it's permanent, and since there are reliable ways for Trainers to force/invoke each individual evolution...yeah.
- Ditto, however, can transform into anything it sees regardless of size. In the games, it can only transform into other Pokémon, but in the anime it has been shown to mimic things like objects.
- The Dog in Secret of Evermore takes a form to reflect whatever region of Evermore the Boy is exploring at the time. In the prehistoric world of Prehistoria, the Dog becomes a hulking wolf-like canine; in the Ancient Grome-inspired world of Antiqua, he becomes a sleek jackal-like hound; in the medieval world of Gothica, he becomes a poodle; and in the sci-fi world of Omnitopia, he becomes a mechanical robo-dog.
- Destiny: Ahamkara naturally and instinctively change their appearance based on what people expect them to look like, or based on what someone wished. The reason many of them look like dragons is because one sensed Lord Saladins subconscious wish to fight a real dragon and promptly granted said wish, turning itself and several of its fellows into towering wyrms.
- Dan and Mab's Furry Adventures has a character who looks like the last person you were thinking about before you meet her. The only way to see what she actually looks like is to close your eyes and think about a person you have never seen before.
- Whateley Universe:
- Fling shapeshifts according to other people's sexual fantasies, of any sex or sexuality.
- Another secondary character shapeshifts into whomever she's looking at.
- The SCP Foundation has several of these:
- SCP-056 is a being that becomes "better" than anyone observing it. It will take on a shape that is more attractive, stronger, and smarter, with the particulars determined by the mindset of the observer. Even when there aren't any people around, if there is a camera monitoring it, it becomes a higher quality video camera.
- SCP-523 is "The Most Unhelpful Object on Earth", an object that transforms into something that seems useful, but becomes completely detrimental when someone tries to use it. For example, if you're trying to put out a fire, it would turn from a pitcher of water to a pitcher of gasoline.
- A teddy bear run through SCP-914 on "Very Fine" ended up as a ball of fluff which transforms into an animated plush toy if held by a sentient being. The toy's appearance and behavior is whatever the holder finds most Cuteness Proximity-inducing. It was removed to be analyzed under controlled conditions later.
- Oliver, a minor character in Worm, changes his face and body according to his basic perception of attractiveness which slightly changes every time he sees a new face, to the point that even his friends have had trouble recognizing him.
- Ex-Super Soldier Shane "Goose" Gooseman of Adventures of the Galaxy Rangers shapeshifts automatically in response to any threat (forming reflective armor against Frickin' Laser Beams, for instance), but if his Series Five implant goes out of whack, he loses control of his power and becomes a danger to himself and others.
- The chameleon. They change colors based on features of the environment like temperature. Despite the common notion, their color change is not based on the color of the surrounding environment; a naturally green chameleon will not change to pink or brown if you pick it up or move it to a piece of tree bark. Apart from specific patterns for things like mating, most of the color changes are darkening, brightening or paling.