The Symbiote



""Of all the parasites I've had over the years, these worms are among the -- hell, they are the best!""

- Fry, Futurama

In biology, a symbiote (or symbiont) is a living organism that lives in symbiosis with another organism. Symbiosis literally means "living together," and it comes in three variations:


 * Mutualism - both organisms benefit from each other's presence.
 * Commensalism - one organism flourishes, the other isn't affected.
 * Parasitism - one organism is harmed, the other flourishes.

In fiction, all types are very frequent guests in Science Fiction and Fantasy. The Heroic Host specifically gets their powers from such an arrangement, though the specifics vary.

Compare Puppeteer Parasite (parasites that control other organism's brains) and Face Full of Alien Wingwong (parasites who use our bodies for reproduction), which could be subtropes of this. Also compare Chest Burster. See also Heart Drive for a similar phenomenon involving biological Soul Jars.

For details on hosts for symbiotes, see Body and Host.

For a version of Mutualism particularly common in Science Fiction, see Translator Microbes.

Anime and Manga

 * In Kurau Phantom Memory, the Rynax-entity merged with Kurau's body benefits from the protection for her recuperating pair, while giving Kurau immense powers in return. It's not quite clear though whether the original Kurau is still in control of her own body or simply a "bystander" in the process.
 * The finale (in the dub at least) makes it pretty clear the original Kurau was just a bystander. After the Rynax leaves her body, Kurau tells her father she can remember everything that happened when the Rynax was controling her, and when she talks to Christmas she says she's not the Kurau Christmas knew, and that even though she isn't the Kurau Christmas knew, she saw everything the "other" Kurau and her went through together, which means the original Kurau was just an observer, watching the Rynax's life in her body until it left. Though, she did seem to have fond memories of the experience.

Comics

 * The color entities of Green Lantern feed on emotion and allow their hosts to manipulate solid light on a much larger scale than power rings. Unfortunately, some of them affect the behavior of their hosts, which can vary from subtle influence to full on Puppeteer Parasite.
 * In The Incredible Hulk's "Crossroads" arc the Hulk went to a planet where the food is poisonous to animals unless they have a symbiote attached.
 * The Symbiotes from Spider-Man, although they have a tendency to turn their host evil. The ones in the Ultimate universe are parasitic, though.
 * The core universe Symbiote species is as well. The Venom Symbiote and it's spawn are considered mutants by the others. Or they were, before they completely wiped out their Always Chaotic Evil brethren.
 * Venom is coming back to this, after bonding with Flash Thompson, realizing that they must rely on each other to survive.

Film

 * And You Thought Your Parents Were Weird has Matt, a ghost, possessing Newman, a robot. Matt needs Newman's body to interact with the world, and Newman benefits from having a smarter mental roommate.
 * Growth has leech-like parasites that infect a human host with their larvae and make their hosts stronger and smarter. However, the larvae rapidly mature and take over the body, reproducing and making their hosts aggressive. They also cause salt to act like acid. Often, mature parasites will Zerg Rush humans when hungry. Rather than infecting and reproducing, they eat.

Literature

 * The Iskoort in Animorphs.
 * The Yeerks too, who are like the Goa'uld in that they skirt the line between mutalism and parasitism. They forcibly take hosts, but it's just as beneficial for them, as in their normal states they're blind, powerless slugs.
 * Similarly, the symbiote in David Weber's book The Apocalypse Troll kills over 99% of its hosts, though in this case it's justified since it was originally developed as a bioweapon, and intended to kill 100% of its hosts. Those who survive, though, gain effective immortality via Healing Factor (and eternal youth into the bargain), enhanced senses and reaction times, and generally superhuman abilities.
 * The symbiote from Anne McCaffrey's Crystal Singer novels has a low success rate for adaptation to human hosts. Those who survive, though, gain a Healing Factor that makes them virtually immortal, barring murder or immediately-lethal accident.
 * In John Varley's Eight Worlds series of short stories, there are the symbiotes; artificially cultures plant-based organisms that are bonded with humans to produce a single organism that has it's own individual animal/plant ecology. They don't breathe or eat, and spend their time in open space, usually touring the rings of Saturn.
 * Likewise, the cave slug in F. Paul Wilson's Healer is believed to be 100% fatal, but the title character is one in a thousand and instead gains the "usual" benefits per the two examples above, along with a voice in his head (which he names "Pard", as in partner). His touch can also heal others of physical and mental illness, making him a figure of awe and legend.
 * The Binod Union in Atavar, so much so that they're considered a single race.
 * The Hitchhiker's Guide to the Galaxy's Babel Fish, a living plot device as a Symbiote.
 * The vampire-fungi from the Necroscope series technically fit here. The fungal-leech gets a host with sentience and opposable thumbs, the host gets enhanced psychic powers including shapeshifting), enhanced strength, enhanced senses, and a craving for fresh blood and human flesh...
 * The Kualkua species in Sergey Lukyanenko's The Stars Are Cold Toys duology are shapeless creatures able to split by mitosis. They are used by the Conclave for anything from translating speech in real-time to piloting suicide ships. At first, the human protagonist is horrified (but not surprised) as to the treatment endured by the Kualkua at the hands of the Conclave Strong races. Later, he is horrified after learning the true nature of the Kualkua (that of a ). This also crosses over into Commensalism and Reverse Parasitism.
 * The War Against the Chtorr. A characteristic of the invading Chtorran ecology. For instance Chtorran gastropedes are covered in neural symbionts (so-called 'worm fur') that vastly increase their senses, making them super-efficient predators. Shambler trees are host to over thirty different species of carnivore that can seek out and devour prey, passing on nutrients to the shambler via their waste products.
 * The K'da from Dragonback. Basically a tiger-sized dragon that can turn into a tattoo, and must do so at least once every six hours. The K'da gets a host, the host gets a powerful guardian, and both get the other's companionship.
 * In Soviet Russia, dragon rides YOU!
 * In Octavia Butler's Fledgling, vampires (or Ina) are like this with humans. In fact, the humans they feed on are called their symbionts. Ina feed on human blood, and humans are addicted to whatever chemical is in the Ina's saliva. The humans also get to live longer (but they can't be turned). There even is a Hemo-Erotic part, with Ina often having sexual relations with their humans.
 * This shows up at least twice in Poul Anderson's Technic History series: one encountered briefly by Nicholas van Rijn, and the the natives of Dido in The Rebel Worlds, who are a combination of three species--the "hands," the "wings," and the "feet."
 * The detective-creature in the books "Needle" and "Through The Eye Of The Needle" was a blob of protoplasm that entered a human host to survive and move around-bordered versions two and three, because the boy was not harmed at first but then became ill in the second book. There was also another creature, the hunted fugitive, who'd taken another body and was a Puppeteer Parasite type.
 * Hal Clement actually coined the word "symbiote" in Needle. He later apologized for this, after biologists pointed out to him that the correct word is "symbiont." But it was too late by then, as lots of other writers had copied him.

Live Action Television

 * The Vindrizi from "Exogenesis," in season 3 of Babylon 5. A race of living recorders designed to preserve the memories and knowledge of their creators, the Vindrizi seek out voluntary hosts who have nothing of their own left to live for.
 * The Goa'uld and Tok'ra in Stargate SG-1.
 * The Goa'uld surf between mutualism and parasitism, since the symbiosis can allow them to take over their hosts. The difference between Goa'uld and Tok'ra is largely the choice whether or not to do this.
 * Made a little questionable when there have been a couple of rare, but still present, instances of a Tok'ra taking a host without consent (maybe a misunderstanding) and even taking over their host (deliberate, if extraordinary). Hmmm.
 * The Trill in Star Trek: Deep Space Nine. The host humanoid body keeps the Trill alive while the host enjoys the cumulative memories, including the skills, of all previous hosts.

Tabletop RPG

 * Very similar to the Vindrizi, the Kergillians from the Over the Edge tabletop rpg (and related card game).

Video Games

 * Peacebringers and Warshades in City of Heroes. They're each a kind of Kheldian, Energy Beings from outside our galaxy who can merge with humans; the humans get powers, and the Kheldians get immortality as long as they have a host; their "natural" lifespan is only ten years. They're an unlockable playable class (well, two Archetypes to be precise), and their powers include Shapeshifting into their previous common forms, including a floating tentacled Glass Cannon and a large armoured Stone Wall, nicknamed the 'squid' and 'lobster' respectively.
 * In Knights of the Old Republic II, a psychic connection of this sort is formed between the player character and Kreia.
 * The fierce Harika and mouse-like Yorn in the third installment of Star Control.

Webcomics

 * The titular symbiotes in Gnoph live inside human lungs, and grant their hosts a variety of superhuman abilities.
 * The Accidental Space Spy: One of alien spies have this, the real body is just a oval. Rest of parts such as hands, eyes, etc were parasites but later adopted to mutual status.
 * Work Sucks: Epicena has a symbiotic monster named Hatch hooked to his...her...its back that has the ability to inhale and capture people Epicena wants. Epicena says Hatch is harmless unless (s)he tells it otherwise.

Western Animation

 * The Worms in the "Parasites Lost" episode of Futurama (see the page quote.)
 * Symbiotes in the Men in Black animated series. Basically, they were metamorphic heads which had to attach to other creatures to survive. Having one attached to you meant you got super strength, shape shifting, and highly powerful regeneration powers; unfortunately, the only one we see is ungodly annoying and clingy, and if you're bonded with one past a certain period of time, it becomes permanent.

Real Life

 * You've got some in your intestines right now, people. They're gut bacteria that eat leftover fiber from your food, and pay their rent with the vitamins they excrete. Lose them due to radiation therapy, high-dose antibiotics, or other causes, and your doctor will make you eat live-culture yoghurt until their population levels are restored.
 * A very particular case of real life symbiotes are mitochondria, which actually live inside the cells of practically all animals (including humans), playing an important role in the metabolism.
 * Although calling them "symbiotes" is giving them too much credit at this point. Mitochondria have been part of other organisms for so long that they are not independent lifeforms in any real sense anymore, but rather an integral organ of the cell they inhabit (which is why they're counted among the "organelles"). They still have their own DNA, though, which you do in fact inherit solely from your mother.
 * Plants have something not dissimilar in their chloroplasts, the organelles that photosynthesize. These too are theorized to have been symbionts at one point, and which are now completely interdependent.
 * It's also theorized that eukaryotic cells in general(cells with nuclei) are also the product of a symbiotic relationship.
 * Those white lumps seen in pictures of humpback whales are actually this trope, as they're giant barnacles that grow nowhere else but on the hides of baleen whales. The otherwise-immobile barnacles get a free ride into plankton-rich waters, at which point they start waving their net-like appendages to feed. The whale can hear which flipper's barnacles are scooping up plankton more rapidly, and turn towards the direction where food (for whale and passengers both) is most abundant.
 * Many "cleaner" species, such as tickbirds or cleaner wrasses, pick parasites (see below) from the surface of larger animals for a living. They get a meal, and the bigger animal gets a de-lousing.
 * Oxpeckers walk a fine line between mutualism and parasitism, since their main diet is their hosts' blood -- they get some of it from the fleas and ticks they eat off of their host, but they will also sometimes peck at their hosts, or reopen their wounds, to get them to bleed.

Anime and Manga

 * The Guyver units from Guyver.

Film

 * Arguably, midi-chlorians in Star Wars. The jury's still out on whether they cause Force powers (which would make this mutualism), or they're merely attracted to people who already have them.
 * A third theory is that the force is a mystical force and that midichlorians are simply what allow people to channel the power of the force (which would again make this mutualism).

Video Game

 * This form shows up in Knights of the Old Republic II as well:

Real Life

 * Truth in Television: Arguably Remoras. They get transported along by their host animals, benefit from their protection, and possibly eat their leftovers. But they don't seem to do anything for or against their hosts.
 * Definitely the Cyomatha exiguna. Sure, it kills the fish's tongue, but don't worry, as it replaces it. The fish is no worse for the wear, apart from now having its tongue having eyes and a brain. Well, they do use up a bit of blood, but usually not enough to matter.
 * You probably have a lot of these on your body without knowing it, such as dust mites that eat shed skin cells or amoebas that feed on the bacteria at your gumline (the latter being a double example).
 * Even a bird nesting in a tree can be considered this.

Anime and Manga

 * The Parasitic Beasts in Parasyte. They drill into people's heads and take them over by eating their brains. Shinichi, the protagonist, manages to get away with one taking over his right hand (it aimed for his head, but he pulled it away in his sleep and it took over his hand in desperation).
 * Although, since the Parasytes already killed the host, they're more like a parasite on the species, since they instinctually crave the host's species.

Comics

 * The Venom symbiotes in Spider-Man are oftentimes portrayed as this.
 * Incidentally, this was the original function of its species. Taking a host, driving them to an early death, and then finding another. The fact that the Venom Symbiote wanted to establish a life-time bond with one person made the rest of its race consider it to be psychotic.

Film

 * The Xenomorphs from Aliens, who utilize human bodies to reproduce via Face Full of Alien Wingwong.
 * The giant crab monsters in Cloverfield were initially parasites clinging to the big guy.

Literature

 * The Yeerks in Animorphs; who in their natural state are little more than breadloaf-sized gray slugs, who need our bodies to free themselves from their senseless prison. A branch of their species became the Iskoort (noted above) and it's stated that there is a chance they will follow that path as well in the distant future.
 * In The Dresden Files short story Day Off, two of the Alphas are afflicted with "supernatural fleas".
 * The Black Worm in John Connolly's The Cancer Cowboy Rides. An inhabitant of the Enemy to All Living Things, Buddy Carson, it grants its host the power to transmit fast-acting cancer at a touch- and enforces its use with agonising pain and the threat of infection. Though the Worm doesn't speak in the short story, Carson mentions a dream in which it tells him that his only purpose is to "Spread the Black Word."
 * In Infected (the novel), the parasites are extra-terrestrial in origin and cause the growth of a new consciousness that encourages the host to kill and maim as much as possible.
 * Lotus in Monster is one of these feeding off the universe.
 * In Peeps, vampires are due to a parasite living inside the body of a human host. The entire book is all about parasites, even with tips about real parasites at the beginning of each chapter.
 * Debatable. While the "parasites" do significantly alter your personality and body to aid themselves (you have strong cravings for meat, want to fight or sleep with everything you see, and hate everything you once loved), they do grant super strength, night vision, immunity to most other diseases, control over rats, and extreme longevity.

Live Action Television

 * Another example of the parasites turn you into vampires route is the dodo parasites in Primeval.
 * The original appearance of the Trill in the Star Trek: The Next Generation episode "The Host". They were given a makeover before DS9. The relationship wasn't as bad as usual, but the character in question did refer to itself as a "parasite".
 * Also, the host of the original Trill was apparently completely submerged - no sign of Riker in there when he was filling in as host. If the Trill hosts minded, it wasn't said, but the relationship between host and symbiote - symbiote is the person you're talking to, host is just a body it uses - is the same as with the villainous host-takers.
 * Then again, Trill symbionts aren't meant to be placed in humans, perhaps explaining this effect. It wasn't long before Riker's body began to reject it.
 * Star Trek II: The Wrath of Khan had parasitic eels native to Ceti Alpha IV, which Khan used to control several Star Fleet operatives.
 * After Man had a species of shrew-like mammals that evolved into a parasite, using their mouth to suck blood from their host like a giant mosquito.
 * The Black Oil a.k.a. Black Cancer a.k.a. Purity from The X Files is an alien virus that gets into your body through your eyes and mouth and assumes complete control over it,.

Video Games

 * The "Zombees" in Dead Rising. The cause of the zombie outbreak is a natural species of Colorado wasp that injects a host with larvae that travels into the brain and takes it over, turning the host into a zombie in which the larvae develops.
 * The Necromorphs in Dead Space.
 * The various types of headcrabs in the videogame Half Life.
 * The X Parasites in Metroid.
 * In Prototype, Alex Mercer gets infected with a virus-specific parasite, which debilitates him until he finds a cure.
 * The Magatama in Shin Megami Tensei III Nocturne. Notable in that, despite being in name a parasite, it has many beneficial effects and only few drawbacks that can be cured or outright prevented with some foresight.
 * Las Plagas in Resident Evil 4.
 * The Zerg Queens in Starcraft love this trope. They have two kinds of nasty parasites at their disposal, ones that crawl inside the host and feed information back to the Zerg, and another that grows inside a biological unit and then emerges Chest Burster fashion.
 * And a subtype of both that infects an entire terran command center, turning the humans inside into something between zerg and suicide fanatics.

Western Animation

 * The Big Tick in Ben 10, who is a parasite that eats planets. Unfortunately, the planet does not usually survive.
 * Parodied with "Brain Slugs" in Futurama; unlike most versions of The Virus, which are typically capable of a bit of subtlety, Brain Slugs are blatantly visible attached to the infectee, and make statements such as "Your mission for today is to go to the Brain Slug planet and stand around without wearing hats", in a stilted monotone.

Real Life

 * And in case you were wondering by this point, yes, you have these as well, although generally a lot less than the mutualistic/commencialistic symbionts as your immune system tends to wipe out the parasitic ones before they become too uppity. Most diseases are caused by parasitic symbionts and the immune response to them.