Trapped in the Host

Father Ben: [After exorcising the demon Pazuzu from Maggie] Now hush, Pazuzu is still among us. But where?

Pazuzu: [Speaking from inside Bart's body] Let me out, let me out! This boy has the darkest soul I've ever seen!

—The Simpsons, "Treehouse Of Horror XXVIII", "The Exor-sis"

There are all kinds of aliens, psychics, or spirits and demons that can take over or possess someone. For the entity doing the possessing, it's often portrayed as easy to get in and get out, comfortably Body Surfing wherever they want to go.

But there's a problem with their latest possession. Something has come up, whether because there is something different or unique about the person they attempted to possess or some sort of special circumstances, and now they're stuck in the host they tried to take possession of. This may be a permanent thing, or it might be a case where they need outside help to get free, but either way, this isn't going to be an easy come-and-go for them.

Compare and contrast with Shapeshifter Mode Lock, where a shapeshifter gets stuck in one form, and Sealed Inside a Person-Shaped Can, where an outside force traps an entity inside a person usually as a form of a Restraining Bolt. Also contrast with Supernatural Sealing and Assimilation Backfire. May overlap with Kill the Host Body when someone is attempting to get rid of the possessing entity entirely.

---

Examples:

Anime & Manga

• Devils in Chainsaw Man that possess human corpses usually can't ever leave, as it's an Emergency Transformation that turns them into a Fiend for the rest of their life. The only one we know to have become a full devil again had her human body destroyed and left behind blood elsewhere that she regenerated from as part of a contract with another devil.
• In Dragon Ball Z, Captain Ginyu has a technique to swap bodies with another person that he uses when he encounters a foe more powerful than himself. After several of these swaps, Goku manages to interrupt Ginyu in the middle of swapping into Vegeta's body and Ginyu winds up inside a harmless Namekian frog instead — the technique requires a vocal command, and since frogs can't speak, he can no longer use it. Aside from some filler where Bulma gave him a Translator Collar, Ginyu would be stuck in said frog for the rest of the series. That is until Dragon Ball Super where's able to use a written command to swap with Frieza's soldier Tagoma, and then proceeded to immediately die in a Curb-Stomp Battle with Vegeta...

Comic Books

• New X-Men: Cassandra Nova can possess other people by amplifying her telepathic powers with the machine Cerebra, which she does to swap bodies with Charles Xavier. After the X-Men succeed in reuniting Charles' mind and body, Cassandra is expelled and becomes a being of pure psionic energy. She tries to reclaim what she believes to be her original body, but possesses the alien shapeshifter Stuff instead, becoming stuck inside his artificial brain.
• Downplayed in the supernatural comic Rachel Rising. The main antagonist, Malus, is a Fallen Angel turned Omnicidal Maniac demon who normally goes from body to body on Earth, possessing them and making them do horrifying things to further his goals, or just for kicks. Once he takes over a body he seems stuck in it until the host dies, at which point he is free to move on again. However, since Malus does aim for the eventual destruction of all humanity and hates our species with a passion, getting his host killed due to reckless actions or even killing them himself just because they're no longer useful isn't exactly much of a concern for him, so he's never trapped for very long.

Fan Works

• Better Bones AU: Hollyleaf uses Sol's attempt to possess her to seal Sol inside her chest, gaining his powers in the process.
• The Rigel Black Chronicles: The Dominion Jewel enters Harry's mind, to fulfill its own twisted ideas about making a deal. She wants self-control, so it will assume control over her magic and her personality. But it didn't anticipate Harry's experiments in creating sentient magical constructs inside her mind. She hasn't been able to create an independently-thinking being, but she has produced a shell bound to obey her and never harm her, and she stuffs the Jewel's magic inside it, resulting in it living inside her head as a subordinate instead of a master.

Films — Live-Action

• For most of Being John Malkovich, entering a portal allows someone to temporarily enter the head of (a fictional version of) famous actor John Malkovich, and see life through his eyes. However, the portal can only be used until a "vessel" is a certain age, and then it switches to a new person. At the very end of the movie, one of the main characters tries to jump into the portal too late and winds up permanently stuck in the new vessel, whom they have no control over and cannot affect or even do anything to make people know that they're inside the vessel.
• Main character John Hobbes attempts to invoke this at the end of Fallen. After being hounded by a vengeful demon which effortlessly passes from person to person and is set on ruining Hobbes's life and killing everyone he cares about, Hobbes lures the demon and the latest host it is possessing to an isolated cabin in the woods, where Hobbes manages to fatally wound the demon's host and poisons himself. The demon is able to pass into the body of the dying Hobbes, but must pass on into another body quickly, or he'll die along with Hobbes, and there's nobody else around. Unfortunately, a local stray cat happens by, and the demon manages to possess it and then travel back to a more populated area.

Literature

• In Animorphs, this is the fate of any Yeerk that tries to possess a Chee, a race of incredibly lifelike androids that project human hologram disguises. The Yeerks assume control of species by molding themselves around their brains, but Chee don't have brains and instead trap the Yeerks in their heads. This makes the Chee excellent spies against the Yeerk invasion.
• In the Merlin-focused books from The Chronicles of Amber, Merlin is followed by a Ty'iga demon, a bodiless spirit that often possesses the bodies of people around him as it attempts to protect and keep tabs on him. At one point the Ty'iga goes to possess Nayda, who is the half-sister of Coral, one of Merlin's Love Interests. The problem is that Nayda had long suffered from serious health problems and suddenly died just as the Ty'iga was starting to possess her, and this left the Ty'iga trapped in Nayda's body. Due to the Ty'iga's spirit inhabiting it Nayda's body is carrying on normally, but the Ty'iga isn't able to Body Surf and jump from body to body as she has in the past.
• Percy Jackson and the Olympians: Through the centuries, the Oracle of Delphi has had many young maidens as its hosts. When its last host made the mistake of telling Hades "I Warned You" after Zeus had killed his mortal girlfriend, he cursed the Oracle to be stuck inside her body even after she died. In the present, the Oracle remains trapped inside its host's now long-dead and mummified body. In The Last Olympian, it is finally freed after Rachel becomes its new host.
• Secret Histories: Truman brags that when a Loathly One infected his mind, his augmented brain rendered it powerless and then destroyed it. Later Subverted: the Loathly One is faking and can assume control whenever it wants to.
• A Song of Ice and Fire: If a skinchanger's body is killed while their spirit is projected into an animal, the animal's mind becomes dominant and the skinchanger's slowly fades away into the background. Varamyr Sixskins meets this end in A Dance with Dragons, but still prefers it to total death.
• In the Doctor Who New Adventures book Timewyrm: Exodus, the Timewyrm (the arc villain) takes possession of Hitler's mind, and then finds it can't get out again. Worse, Hitler learns to draw on the Timewyrm's powers to his own advantage.

Live-Action TV

• In the Angel episode "I've Got You Under My Skin", the group exorcise a demon from a child's body, only to learn that the demon wanted them to do it because the kid was so evil it terrified the demon, and ever since it possessed him the demon had been stuck inside the kid, unable to escape.
• Crusade episode Appearances and Other Deceits has an alien entity possessing various crew members. The entity was isolated to a deck but was using the possessed crew members as hostages in order to control the ship. When the oxygen to the deck was cut, the entity escaped from all but one host, who then searched around for a new body, finding one in a space suit — said new body was paralyzed from a shot earlier in the episode. Said body was ejected into space and fired upon.
• Guillermo del Toro's Cabinet of Curiosities: In the episode "The Autopsy", Dr. Winters finds out a sapient Puppeteer Parasite alien (named in the subtitles as "The Traveller") that feeds on blood has taken control of Sykes and killed all the other miners. The alien captures Winters and straps him to the autopsy table in preparation to make him its new host. However, Winters gets the better of the alien by stabbing out his eyes, puncturing his eardrums, and slitting his throat before it can completely implant itself inside him, leaving the alien with a hapless, dying host body.
  The Traveller: LET ME OUT! LET ME OOUUUTT!!
• War of the Worlds (1988): Unlike his fellow alien invaders, "Quinn" is immune to Earth pathogens, but is also stuck in the human body he possessed, and so works to covertly thwart the invasion.
• One episode of The Winchesters sees Ada interrogate a demon and then force him to possess a bonsai tree so that she can find him again if she needs more information.

Podcasts

• In the first episode of Malevolent, when the entity/John Doe explains their particular situation to Arthur, he describes it as Arthur having accidentally cursed both of them by binding them together. Later in the series, he remarks not enjoying being trapped in Arthur's body. Though they do eventually grow to appreciate each other, ultimately John wants his own body, separate from Arthur, and that's a long-term goal for the characters as the series progresses.

Tabletop Gaming

• Warhammer 40,000:
  • Some radical Inquisitors have been known to summon Daemons and bind them to "expendable" humans known as Daemonhosts.
  • Ax’senaea the Thrice-Possessed was convinced to perform a ritual that summoned a Greater Daemon of Slaanesh into her own body, with her tutor expecting her to find out the hard way why this was a bad idea. Instead, her solipsistic self-obsession turned out to be so strong she was able to overpower it through sheer will, trapping it helplessly within her body and leeching off its power for decades until she banished its drained essence back to the Warp. Then did it again, twice, and would have kept doing it except Slaanesh elevated her to daemonhood on the fourth attempt.

Video Games

• In Custom Robo Battle Revolution, it's eventually revealed that the initially formless abomination Rahu possessed and assimilated a Robo that it couldn't leave thanks to the mental Dive system Robos use to link with Commanders, which stuck it in a physical body people could finally fight back against and seal away.
• Fate/Grand Order: In the 6th GUDAGUDA event, the evil deity Amanojaku goes around possessing people with weak willpower because he is completely powerless without a body. Knowing this, Takechi Zuizan and Izumo-no-Okuni correctly predict that his next target will be Zaizen himself, and create a seal in advance to ensure that Amanojaku will be unable to escape. When it happens, Zaizen commits Seppuku to take Amanojaku with him.
• Final Fantasy XIV:
  • Invoked by white auracite. The Ascians are normally able to retreat to the rift between worlds via their Crystals of Darkness whenever they would be trapped or killed. This gives them time to find a new host body to once again wreak havoc as the heroes are unable to chase them. However, Moenbryda realizes that it may be possible to temporarily trap the Ascian's soul inside a piece of white auracite, which can then be shattered by a powerful stream of aether called a "blade of light", creating a brief window in which the otherwise undying sorcerers can be killed.
  • The black mages of Mhach developed rituals to summon voidsent to do their bidding by binding them inside hosts compelled to serve them. This is most prominent with Scathach, the Shadow Queen and one of the sovereigns of the void, who was forced inside the body of a mortal woman and sealed within the Void Ark to be used as a power source. She's thus heavily weakened when the Warrior of Light and their party face her 1,500 years later, as she's confined by her mortal vessel and more than a thousand years of having her energies drained. That said, she's still extremely dangerous and powerful enough for Diabolos to plot to absorb her aether to turn himself into a first-rung voidsent and the final boss of the raid series.
• Ōkamiden: Downplayed. Following the final boss battle, Akuro is left severely weakened due to being exorcised from Kuni. Desperate to reclaim his powers, the villain agrees to possess Kurow, who had offered himself to be a vessel. However, this turns out to be a trap, as Kurow is revealed to be a living doll, developed for the express purpose of sealing him. Unfortunately, the demon is too strong and starts to break free, forcing the heroes to kill Kurow in order to slay Akuro for good.

Webcomics

• Shortly before the start of Archipelago, a Raven spirit tried to possess a dying man via his eye, but the man gouged his own eye out before the Raven could fully take over. This basically broke the man's psyche and trapped the Raven inside of him. The pair washed up on shore, where the comic starts.
• El Goonish Shive: The Body Surfing aberration Sirleck takes over Ellen's body so he can take over Magus once he gains a new body. However, Sirleck finds that Ellen is stopping him from leaving her body, either because she's made of magic or because she's "just that awesome". Either way, she holds Sirleck in place then releases him in time for Magus to kill Sirleck before he can take another host.
• Girl Genius: Happened to the Other AKA Lucrezia Mongfish twice. First time, the Other tried uploading themselves to Agatha (who she planned to have Raised as a Host) and took over her body for a while, but got trapped by Agatha's locket and remained that way for most of the comic. Second time, they tried uploading themselves to Zola, who had her family prepare for this and Zola was able to get all Lucrezia's memories uploaded to her instead.
• The Greenhouse: The demon 'Red' was only partially summoned before getting trapped, first in a mirror, and then in main character Mica, the girl who broke it. She can't leave until an expert in blood magic cuts her out of Mica's soul, Mica completes her summoning (receiving favors of her choice in exchange for the already established price of her soul), or Mica dies... and Red is increasingly leery of that last option, since she's not actually sure she'd survive it either.
• Gunnerkrigg Court: Reynard was granted the ability to possess any body with eyes by Coyote, but when he jumps to Annie's stuffed animal in the first few chapters, he is trapped there, as the toy being Annie's property puts him under her control. Reynard also meets Hetty, another spirit trapped in similar fashion, though a much more malevolent one who's implied to have killed her previous owner and hates and plots to kill her current one, even though he has no idea she exists.
• In the first chapter of the Pokémon Mystery Dungeon webcomic, Multiverse Level Screw-Ups, a Haunter that is named Syrena gets her house accidentally crashed into, and when Avi misinterprets her annoyance as a boss battle, she tries to knock Avi out with Destiny Bond, only for it to be dodged and go to an unconscious Lory, who is in the process of being revived by a Reviver Seed. As a result, a reverse effect of Destiny Bond occurs, causing Syrena to be fused into the Chikorita's body.

Web Animation

• Spooky Month: After spending two years in the attic because Skid and Pump refused to release him, the demon Moloch possesses Dexter, an exterminator Lila hired, to escape and get revenge on the two. When Skid expresses doubt that it's actually Moloch, Pump suggests he turns his head around to prove he's a demon. Moloch does so... and breaks Dexter's neck. While it initially seemed to outright kill him, later episodes reveal that Dexter's body survived in a paralyzed state, and Moloch was now trapped in it.

Western Animation

• Beast Machines: In the episode Spark of Darkness, Megatron's spark gets separated from his body and gains the ability to possess and reanimate corpses, but after the heroes "re-polarise" his spark he gets trapped in the next body he possesses, a puny Diagnostic Drone.
  Megatron: I live! I live! I—...what kind of puny body is this?!
• Jackie Chan Adventures: In order to get out of eternal torture, Shendu offers to free his demon brethren from their prison by possessing a human host. His fellow demons, unable to trust him for his previous betrayal, put a curse on him that prevents him from leaving whoever he possesses. At first, Shendu isn't worried as he had full intent on possessing Jackie Chan. However, he instead accidentally possesses Valmont, forcing the two of them to work together again.
• The Simpsons: In "Treehouse of Horror XXVII", Maggie is possessed by a demon named Pazuzu when Homer orders a possessed artifact online. After an exorcism expels the demon Pazuzu out of Maggie, it possesses Bart Simpson. Pazuzu promptly starts begging to be set free from Bart, saying Bart has the darkest soul he has ever encountered.
• Wander over Yonder: Sourdough the Evil Sandwich, formerly known as Queen Entozoa, is an energy being who possesses a new host every 1,000 years. In "The Fancy Party" it tries to possess Lord Hater, but Wander Heimlich maneuvers it out of him and into a sandwich, leaving it stuck possessing the sandwich for the next one thousand years.

---