Monster: Wyvern Parasite

(06.09.2012: edited from original for typos and clarity)

An insectile nightmare that grows inside a person, consuming their organs and wearing the host's body like a shell. It looks sort of like smart, fast zombie, until 4' of glistening wet spines and legs and chelicerae reaches out of an empty eye-socket and latches on to your face.

Description and Biomechanics: 
Full grown parasites resemble 5-6' long black centipedes, with a cluster of long grasping claws and hooked chelicerae at their mouth and every other set of legs replaced by retractable tendrils. When inside a host body, they usually wind themselves around the spinal cord, or coil up inside the ribcage or the skull. Their tendrils branch out through the body and take over muscle control from the host nervous system. This gives the parasite reasonably good gross motor control, but fine motor control, facial expression and the like are beyond them.

The parasite cannot use the host body's mind or sensory organs. In any case, the eyes and brain are usually among the first organs to be consumed in human hosts. Instead, the parasite uses its own senses through convenient openings in the host body - often peering through an empty eye socket, open wound, or the host's mouth. If this is not practical, the parasite will push some of its tendrils through the host's skin and use them to pick up scent and as 'ears' to pick up vibrations in the air. Inside the host body, these tendrils regulate the flow of nutrients, replacing both the respiratory and circulatory systems. When severed, the tendrils will bleed a thick black fluid that clots rapidly on exposure to oxygen. Because of this, an infected body can only be 'killed' by killing the parasite or driving it out of the body. Superficial damage, including the loss of limbs, will not stop them. Parasites can survive outside a host, and will leave if the host body is no longer effective. By going into a dormant state, a parasite can last for decades or longer.

Wyvern parasites are always hungry - their growth and reproduction require large amounts of fat and protein. The parasites feed by stretching out of their host and using their flesh-dissolving venom and grasping mouthparts to devour the flesh and bones of anything they can catch or find. If food is scarce, the parasite will consume the muscle and fat of its host body. This hunger reduces the parasite's ability to think, and starved parasites lose all thought for risk or subtlety.

Parasites reproduce asexually, growing a small number of larva in a sort of fleshy bulge about a foot behind the creature's head. As the young grow, they starve the parent, causing it to become ravenous regardless of how much it eats. In this stage, the parent will mindlessly pursue live prey. The parent's head will shoot out of its host body and latch on to the victim. Once attached, the creatures tears into the victim's flesh and vomits one of its larvae into the cavity.  

Once inside the victim's body, the larva will tunnel to a good central location - like the ribcage - where it will consume tissue and begin working it's tendrils throughout the new host. The infection process is usually enough to kill the victim, but if it doesn't, the massive tissue damage from the larva will cause death in a matter of minutes. The larva usually gains limited control over the new host within an hour or two and it will reach maturity over the next couple of days.

Wyvern parasites communicate with each other through a complex mixture of volatile chemicals that they exude through tendril surfaces that are exposed to air. To humans, the smell of these mixtures is usually too faint to detect. However, large groups of infected or areas in which the infected live develop an acrid smell that has been described as a mixture of rancid meat and burnt plastic.

Enounter Notes:
Wyvern parasites are intelligent, but not particularly sophisticated. They are cunning, fast, and have no remorse or pity. Although they lack the fine motor control needed to use firearms and most tools, the infected have no trouble navigating crowded corridors, climbing ladders, or opening doors.

They will adapt to the strengths and weakness of their prey. Infected who are accustomed to hunting humans will tend to be most active at night, and will hunt in small groups in unfamiliar or dangerous areas to avoid causing a massive response from human authorites. They prefer ambushes and fast close range attacks from concealment. The more experienced parasites will try to use bait, such as a wounded and vulnerable human, or will drive prey into an ambush. Large masses of infected will usually be very hungry - sometimes starved to the point that they will rush prey without regard to personal safety.

In combat, they try to overwhelm and pin opponents to prevent them from using firearms and melee weapons. The infected are surprisingly strong, but have limited natural weapons. The infected tend not to punch or kick, preferring to gouge and tear with their hands. As a coup de grace or a last resort, the parasite may partially emerge from their host and bite their prey, inflicting damage with the long, hooked teeth that line their mouth and their venom.  

Mechanical Notes:
Outside of a host, the parasites themselves are not particularly strong or fast, though they are adept at hiding in small dark areas and are exceptional climbers. The parasite's bite does considerable damage, both from physical trauma and from the venom that they inject. When inside a host, the parasite is much more durable - the hosts body can usually take a fair amount of punishment before it will not longer function. Damage to the head or chest cavity can harm the parasite however. The host's speed and damage will depend on the condition of the body, but infected humans are usually slightly stronger and faster then they were before being infected.

Scenario: Slow motion apocalypse.
An low-intesity infection has taken root in the slums of Detroit (or some other failing metropolis). There are rumors of people disappearing from the streets at night. Locals talk in hushed voices about the screaming and the ragged gangs of men and women, half-seen in an alleyway or an open sewer grating as they watch for easy prey. The police won't get involved. Most of the missing are nobodies, and the cops can barely keep up with the crimes that matter. Right now, the infected are just a problem for people on the edges of society, but the infection is self-reinforcing. The more infected there are, the faster the infected population grows. They infected are already too numerous to contain. Entire city blocks have gone completely silent. If the infected are not stopped, they will rise up and devour the city.

The PCs may become involved when someone they need (or care about) dissappears, or when a small group of infected attack them. If nothing else, they will likely be caught up in the chaos of the first major outbreak, as the infection spreads through the streets, consuming everything in its path. 


  1. I will probably end up using these (with your permission, of course) in my Nwod campaign, or maybe even my Tundra setting for Pathfinder (there are a lot of bugs in it). Sweet write-up

  2. Thanks!

    No problem - it's here for people to use. I put it together for d6 game that was equal parts cyberpunk and survival horror, but it should work just about anywhere.