And for the first time, the cowboy had an image of something inside of himself, like a great black worm that had found purchase within him. It lay in his bowels, feeding off him, slowly turning his cells to black, simultaneously destroying all that was human about him while keeping him alive, pumping its unknown poisons into his system. If it had a consciousness, then it was beyond the cowboy's capacity to understand. All he knew was that it had chosen him as its host, and if he did not do what it wanted then it would destroy him.
Thibor Ferenczy: In the beginning, all things were equal. The primal vampire was a thing of Nature no less than the primal man, and just as man lived on the lesser creatures about him, so too lived the vampire. We both, you see, were parasites in our way. All living things are. But whereas man killed the creatures he fed upon, there the vampire was kinder: he simply took them for his host. They did not die indeed they became undead! In this fashion a vampire is no less natural a creature than the lamprey or the leech, or even the humble flea; except his host lives, becomes near immortal, and is not consumed as in the normal manner of massive parasitic possession. But as man evolved into the perfect host, so evolved the vampire, and as man became dominant so the vampire shared his dominance.
Boris Dragonsani: Symbiosis.
Thibor Ferenczy: I can read the meaning of the word in your mind, and yes, that is correct - except the vampire soon learned to keep himself secret! For along with evolution came a singular change: where before the vampire could live apart from his host, now he was totally dependent on him. Just as the hagfish dies without its host fish, so the vampire must have his host simply to exist.
A Guardian's power makes a rich feeding ground. Do not be revolted. There are parasites that may benefit the host... teeth sharper than your own.
—Description of the Whisper of the Worm, Destiny