An asymmetrical, or, "parasitic" twin completely dependent upon its host sibling for life, serves as a fascinating reminder of the fragility of embryonic development. When used as a narrative device, the parasitic twin becomes a potent metaphor for codependency and the potential agony of familial relationships. When twins do not fully separate, great stories happen!
Here are some of the best:
Kuato from Total Recall
Kuato was the rebel leader and resistance fighter who lead a telepathic campaign against the evil Vilos Cohaagen – all while embedded in his brother George's stomach. He helped Douglas Quaid (Arnold Schwarzenegger) unlock his memories, and revealed to him the secret of the ancient Martian reactor, which was capable of providing the red planet with a breathable atmosphere. He then dies shortly after.
Luckily, Kuato is survived by his performer: character actor Michael Bell.
Leonard from the X-Files
A fully traumatizing episode for viewers of a certain age, Leonard, the in fetu twin of Lanny (Vincent Schiavelli) detaches from his brother's esophagus each night in search of a new host body, hoping to escape his brother's destructive alcoholism. Though portrayed by a crude marionette, Leonard's concept, motivations and surreal movements proved him to be among the show's creepiest antagonists – and perfect for a climactic showdown inside a circus funhouse.
Though all he wanted was a chance at survival, away from his brother's self-destructive behavior and severely damaged liver, Leonard was able to find some solace with a new host body – after he's eaten by a tattooed man named the Conundrum.
Belial and Eve from the Basket Case franchise
A trilogy of films from Frank Henenlotter, concerning a man named Duane and his underdeveloped twin brother whom he totes around in a basket. While the first film concerns the pair murdering the very doctors responsible for separating them, the sequels add a counterpart for Belial, named Eve — an identically deformed young woman. Though the pair manages to sire twelve children, Eve is killed shortly after giving birth by a local sheriff. This inspires Belial to build a giant robot mech suit and seek revenge (Part III, rent it).
Duane also finds romance with the daughter of a woman (Annie Ross) running a refuge for people with similar birth defects, named Susan (Heather Rattray): she's been pregnant for six years with a worm-like progeny of her own.
That Detweiler Boy
In this short story by Tom Reamy, a private detective named Mallory investigates the murders of nine people whose bodies have been discovered completely exsanguinated. His inquest leads to a young man named Andrew Detweiler, popular and handsome but for a spinal abnormality resulting in a slight hunchback. Of course, it's really a rubber foam encasement to secretly tote around his brother on crimes sprees (kinda like Master Blaster!).
By the story's climax, he's described very thoughtfully in this great reveal:
"Something came around the end of the couch. It wasn't a cat. I thought it was a monkey, and then a frog, but it was neither. It was human. It waddled on all fours like an enormous toad. Then it stood erect. It was about the size of a cat. It was pink and moist and hairless and naked. Its very human hands and feet and male genitals were too large for its tiny body. Its belly was swollen, turgid and distended like an obscene tick. Its head was flat. Its jaw protruded like an ape's. It too had a scar, a big, white, puckered scar between its shoulder blades, at the top of its jutting backbone."
As it turns out, the Detweiler brothers need a steady influx of human blood if they're to survive their post-operative separation.
Printed in 1977, That Detweiler Boy has been reissued numerous times, becoming a highly influential classic of the body horror genre.
If you're starving for an earlier example, the 1934 medical mystery novel, The Cadaver of Gideon Wyck, written by Alexander Liang, reveals a character to have one in a surprise reveal.
Bill Keller from Dr. Bloodmoney
Philip K. Dick's bonkers post-apocalypse novel Dr. Bloodmoney features a terrific example in Bill Keller, an internal twin able to telepathically communicate with the dead while still inside his sister, Edie. When Bill plans to put a stop to the book's psychokinetic antagonist, Hoppy Harrington, Hoppy uses his powers against him, pulling him outside his sister— where he's quickly swallowed by an owl. Inside, Bill is able to engineer a body-swap with Hoppy, leaving his adversary to suffer his intended fate. Full of mouse skeletons, I bet.
Morty from The Ventriloquist's Dummy
Bobcat Goldthwaite is an aspiring puppeteer seeking mentorship from his hero, a ventriloquist played by Don Rickles, in this great episode of Tales from the Crypt. Naturally, the secret to Mr. Rickles' success is that his puppet, Morty, is actually his asymmetrical twin brother joined at the wrist.
Interestingly, Morty's voice actor was left uncredited, dividing fans on which actor they think provided his high-pitched bluster for the episode.
Roma & Impakta from Darna
Enemies of Darna — the Filipino comics superheroine whose long career reaches back to the 1940's — the villainess Roma, (played by Nadine Samonte on the current television series), and her brother Impakta — "Impy" for short — have plagued her for years as a steady threat. Despite her age, Roma keeps her youth and beauty with an assist from Impy, her parasitic demon brother jutting from her shoulder blades. Impy kills mortals and eats their hearts to prolong his strength— and Roma's complexion.
George Stark from The Dark Half
George Stark is the fraternal twin of author Thad Beaumont (Timothy Hutton), initially mistaken for a brain tumor. Composed of "an eye, part of a nostril" and "some teeth", one of which has a small cavity, Stark lives inside the brain of his famous brother, helping him write fiction — Stark likes to write horror novels, whereas Beaumont aspires to produce more "literary" fare.
After Thad symbolically buries his George Stark identity, Stark somehow returns as a physical Timothy Hutton-shaped manifestation, terrorizing Thad in a complex plot to replace him through his writing.
The film is based on the Stephen King story and directed by the great George Romero.
Little Sis from Imprint
In Takashii Miike's Masters of Horror episode — which Showtime deemed too disturbing to air – an unnamed girl working in a brothel reveals her life story to a syphilitic Billy Drago – omitting one detail. She carries a "Little Sis" on a supernumerary hand growing from the top of her head.
The episode was adapted from a story by Shimako Iwai called Bokee, Kyotee, which translates to, "Really Scary".
Hideki from Evil Dead Trap
This terrific monster film from Japan features a TV crew investigating a mysterious warehouse after it receives a creepy videocassette from the same address. Naturally, they're picked off picked off one by one by a conjoined twin named Hideki and his naïve brother seemingly unaware of his sibling's activities.
Two-Headed Parrot, AKA Pete & Repeat from Power Rangers
In an episode of Mighty Morphin' Power Rangers – Rita Repulsa unleashed "the Two-Head Parrot", (re-named Pete & Repeat on its action figure packaging) as she was ruminating on the idiom "two heads are better than one". The Rangers are able to exploit the creatures' weakness for mangos to defeat them.
This character was actually created specifically for US audiences, when Saban commissioned more monster footage after tearing through the available monsters on Kyoryu Sentai Zyuranger.
Strangely – the Two-Headed Parrot pleads for his life before the Ultrazord — to which the Red Ranger, Jason, replies, "Sorry! We have no choice!" and blows them up both.
What did he mean by that, exactly?
Johnny Dee of the X-Men
Johnny Dee is a mutant in the Marvel Comics universe with a squid-like twin living inside his stomach. His mutant power is to somehow produce voodoo dolls when DNA samples are placed in the squid's mouth. For instance – if he can get a hold of a strand of hair, or someone's fingernail, the squid will spit out a clamshell-like capsule containing a naked replica of that person, like a vending machine designed by Botticelli. These replicas allow him to control the people they're modeled from.
Other characters from the X-Men line who may apply include Maggott – who owns a living intestinal tract – Tusk – capable of generating pint-sized, hunchbacked replicas of himself between two horn-like growths (how does that work?), and Cassandra Nova – Professor Xavier's evil twin sister, who's actually a "mummudrai" – or, a psychic parasite born bodiless on the astral plane.
Pinoko from Black Jack
In this Manga series about a medical genius named Black Jack, his loyal sister, Pinokom was actually a teratogenous cystoma living inside one of his patients. She's eventually given a new body by Black Jack.
Christopher from Kingdom of the Wicked
In this comic book series by 2000 AD writer Ian Edington and illustrator D'Isreal, a bedridden child named Christopher Grahme is prone to blackouts, receding into a fantasy world called Castrovalva aesthetically modeled on the First World War. It's revealed these blackouts are caused by a parasitic twin attached to his central nervous system.
Misquamacus from The Manitou
Not technically a "twin", Susan Strasberg has to contend with the Native American shaman Misquamacus rebirthing himself as a fetal growth on her neck in the 1978 film, based on Graham Masteron's classic story.
Tiny Attorney from The Venture Brothers
While Dr. Venture's twin Rusty also qualifies, these Matlockian southern gentlemen were hired to prosecute the Monarch in "The Trial of the Monarch".
Andy Goldman from Futurama
Fry's former neighbor, Mr. Goldman was somehow able to survive one-thousand years, and now finds himself attached to a dominant, sewer-dwelling mutant. I'm sure there's a story there.
Robin from Teen Titans Go!
In a recent episode, it was revealed Robin wears a domino mask to conceal a parasitic twin growing from his left eye. Is he The Boy Wonder, or the Boy Beyond Belief: Fact of Fiction? Somebody call Jonathan "Two-Takes" Frakes…
In this BAFTA-nominated short from stop-motion animator Robert Morgan, you'll find an excellent example. It's about a pet-stealing mutant– but you have to wait till the end…
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