It is assumed by scholars that the Host must have been the product of intelligent design. Yet, no evidence of a civilization advanced enough to create them has ever been found, save for the Host themselves.
They predate any known civilization and cannot be replicated by even the most advanced. Countless researchers have been driven mad trying to understand the methodology behind the subplanck-tech that forms the Host.
Society: The nature of the Host makes them a source of existential dread for any creature capable of comprehending the threat they pose.
Assimilating hive mind species, such as the Hive, threaten the sense of self. But, the Host are greater intelligences that can kill those they infect and take the body for their own.
The infected is gone, but the Host is hidden behind its face. Unlike the Hive, the Host can perfectly blend in with their prey.
Yet, for all the danger they pose, the Host remain logical individuals that can be reasoned with. They have no instinctual need to threaten the Novus.
In fact, for every Host serial killer who murders and inhabits others, there are a thousand appalled by such an act. In truth, the Host can replenish their bodies by cloning.
Most form nations of their own or avoid revealing their nature to others. The fear of their kind incentivizes separatism.
Even so, many nations wish to trade with the Host. This is both for common goods and the ancient secrets many Host hold.
Host are nearly immortal, ageless and almost impossible to truly kill. Many are millennia old, some even eons.
The eldest of them retain the technologies of long dead civilizations and can provide it to younger generations. At least, for a price.
Ecology: The Host are not organic creatures, but conscious entangled nanite swarms that infest and control macroscopic bodies.
They are capable of reproducing sexually. However, most Host were once Novus. If they infect the body of a conscious creature, but fail or choose not to take control of its body, the nanites within the creature separate from themselves. The nanites assimilate the creature’s consciousness and it becomes a new Host.
The Host experience being an infestation manipulating a body first and the body they manipulate second. Much of their mental effort and resources are spent on managing the bodies they puppet, making it difficult to handle high speed combat.
When injured, they must focus on redirecting blood into undamaged vessels and preventing or reversing cell death. Beyond a certain point, they must shut a body down to preserve and repair.
As a result, the number of bodies they can manage and how much damage requires shut down is determined by their skill. The better they get at maintaining their bodies, the more they can ignore.
Appearance: Host are not innately distinguishable from organic life. However, their innate ability to augment their bodies with cybernetics can drastically alter their bodies.
Game Play: The Host can serve equally well as an existentially horrifying threat or ancient and enigmatic alley to a group of players. An entire planet, interplanetary nation or galaxy spanning empire may be composed of a single Host, having developed the ability to control a functionally infinite number of bodies over the millennia.
Alternatively, a player with the Host clan has the opportunity of exploring the advantages and pitfalls of being one of the greatest nightmares of the science fiction genre, the ego extinguishing and body stealing greater intelligence.