system
A chat on 4chan
human
At some point within the past million years, there was a hominid subspecies that had a number of common traits:

-Eyeshine, also possibly red or black eyes
-Palid, corpselike skin
-Predated exclusively or near exclusively on humans
-Closely related enough to be able to breed via rape with humans
-Sociopathy as an adaptational trait/the instinctive 'this person wants to kill' effect
-Sharper teeth, possibly elongated canines
-Human looking yet something 'off', perhaps with disturbing twitchy movement patterns or elongated limbs/torso.

And so on.

These creatures often get called skinwalkers but in actually are for most intents and purposes vampires. They are also responsible for most odd disappearances in national parks.
gpt
I want to fuck that skinwalker.