Symbiotes are an alien race that feeds on the negative emotions of its host. Also referred to as the Synoptic. They exist in a near liquid form. The Symbiotes were scattered across the galaxy after their home planet was devoured by the world-eater Galactus. For some reason, Galactus could not siphon the life-force from the symbiotes themselves; however, this event left all the symbiotes psychologically traumatized. The race is now nomadic and lives on various worlds throughout the cosmos.
Symbiotes often have a give and take relationship with their hosts, but usually take more than they give. When Spider-Man was first bonded to the Venom symbiote during the Secret Wars, it seemed too good to be true: he no longer needed web shooters or web-fluid, he was stronger, and he could morph the symbiote at will between street clothes and his costume. The negatives quickly became apparent, however, as Spider-Man became more violent and was constantly exhausted. He discovered that this was because the alien was taking his body out on patrol in his sleep. Spider-Man rejected the alien and it found its way to Eddie Brock. Since then there have been numerous other symbiotes; most are relatives of the Venom symbiote who were born on Earth.
Symbiote biology is a bit conflicted between generations, but the seemingly undisputed facts (except in the case of Anti-Venom) is that they amplify the physical strength, agility, and healing of their hosts, are vulnerable to sonics and fire, reproduce asexually, and seemingly grow stronger with each generation. Symbiotes also have an amazing camouflage ability, and it seems they can absorb the abilities of previous hosts (having bonded with Spider-Man, it gave later hosts wall-climbing abilities). They are empathic, usually drawn towards negative emotions, and feed heavily on the brain-produced chemical phenethylamine. The loss of phenethylamine is the very thing that leads the hosts of the symbiotes to become violent and mentally unstable, and is the largest drawback to being the host of one.
The discovery of a few dead symbiotes was only the beginning: Carnage, Venom, Scream, Hybrid and Anti-Venom have arrived on the scene. Along with the mysterious appearance of a new batch of Test Subjects, Spider-Man and S.H.I.E.L.D. look for help in the most unlikely places. It was revealed that the Green Goblin found a way to control the symbiotes by exposing them to one of his serums.
Known Symbiotes:
Venom
Carnage
Scream
Hybrid
Symbiote Related:
Agent Venom
Anti-Venom
