These are not your ordinary, run-of-the-mill beautiful, seductive beings of romance and hunger you read about everywhere. No, the vampires of this world are very different, and very alien than anything anyone would suspect.
The Y’vrr (pronounced ih-vear) are ancient beings of an extra-dimensional nature that stole into our world at the start of the Shadow Wars. In order to survive in our world, the Y’vrr had to find hosts to dwell in, and after several unsuccessful tries, they finally tried humans. Humans, it was found, were perfectly suited to their needs and they made themselves right at home. The Y’vrr also needed sustenance, and found that the same life force sustained humans suited them, the life energy found in blood, though they found they did not actually need to eat their victims to attain the energy. All they need is the blood.
The Y’vrr have powerful psionics and mind-altering powers which they used to lure and subdue their prey. They may alter what you perceive them to be, and can call you to them by putting you in a trance-like state. They can control minds and cause you to do things you would never do. However, the Y’vrr are an alien race, and one that does not understand humans. They do not think to seduce and romance, they simply control. They may make themselves appear more appealing by appearing to be a normal human, but they do not think to make themselves appear handsome or beautiful, because the majority of the human population is simply not that way. They will appear to be an average person, but one who behaves incredibly strangely. They are singularly intent when on the hunt, often just standing and staring, and always with a blank expression (for they do not understand facial expressions). They do not respond to human interaction, they only stare, and when they capture your eyes you are theirs. While the Y’vrr do not understand individual languages, they can easily pick out the meaning of what is being said by reading the mind, and can talk to one another via telepathy, so they have no use for language or speech. So imagine an almost painfully average person, ordinary but pleasant to look at, in average but pleasing clothes, just standing on the street corner, arms hanging limply at his or her sides, staring straight into you and not interacting with anyone or anything else around them. Just staring. And then suddenly you cannot help but to walk towards them, and everything else in the world is meaningless. And then there is darkness, and pain, and finally, nothing.
That is what you will see.
The Awakened, however, can see something much different. A shell of a human being, wasted and bone thin with leathery, sagging skin, lank, thin hair, and milky white eyes, usually naked, standing and staring, the world moving around them as if they weren't there. That is, until the Y’vrr is provoked, or attacked. Then the Yvrr changes in hideous ways, sprouting many long, needle-like teeth, razor claws, bone spurs, extra limbs, and can end up looking like something out of "The Thing". Their wasted form is a lie, as they are capable of great strength, speed, and agility when they need it.
The Y’vrr themselves are a nasty little spider-like being that live within the host. Their transitory state is a black ichor that usually enters the victim through an orifice, or directly into the bloodstream via an open wound. Once inside their victims, they begin sucking all of the essence, energy, and soul out of their host until they are little more than a walking corpse, then they may alter their host form as they see fit. They cannot abide strong light, and so they must hide during the day in underground lairs and come out when darkness falls. Because they are so alien, and utterly inhuman, they see no need to surround themselves with luxury and decadence. An abandoned building, basement, tunnel, cave, crypt, sewer, etc will suffice. Anywhere where it is dark. The Y’vrr also do not sleep. They simply curl up into a ball, milky eyes wide open, and enter a trance-like state until the sun goes down, then they venture out to hunt.
Because they live off of life energy, and are constantly preserving their host bodies with this energy, the Y’vrr are essentially eternal. Once the Y’vrr has completely taken over it's host and assumed it's natural form in the chest, the Y’vrr is bound to it's host body forever. Using life energy, it can repair most damage done to the host, however burning their host body, or cutting off it's head, ripping the chest open and extracting the Y’vrr itself, or otherwise inflicting severe trauma to the host or Y’vrr will cause it's death.
The Y’vrr reproduce by injecting a human (or other creature, but humans are preferable) with it's reproductive fluid, a black ooze that it either vomits into the victims mouth, or bites and drools all over the open wound. The black substance absorbs into the bloodstream through the tissue walls, and begins eating away at the human from the cellular level up, eating away at their life force and forming itself in the chest until there is nothing left of the human, and the Y’vrr is complete. The process usually takes a few weeks to complete. During that time, the human's health will deteriorate, and he/she will begin acting strangely, almost psychotically as their minds and souls battle against the Y’vrr, but it is always a lost fight. They start being afraid of sunlight, and alienating themselves from their loved ones. They no longer go to work, and after a week or so will start killing and eating or otherwise mutilating their pets and other creatures in the area. Often the newly changed will be institutionalized, but any drugs they are given have no effect, and eventually, as they waste away, they become stronger, and will eventually break free of any bonds and either escape or go on a rampant killing spree until the Y’vrr can completely subdue and destroy the host spirit and claim full control of the host.