"Reasonable. So, I am a vampire, which is a type of demon. Most nonhumans are demons. Some are gods instead. I suspect you are not properly a demon and you certainly don't appear to be a god. Degree of mortality varies widely but I haven't heard of anything that cannot theoretically die, just things whose destruction would be difficult to accomplish in practice. This planet is called Earth and it is where most humans live, and nearly all vampires since vampires are all former humans; demons who don't live here live in any number of other places categorically known as 'hell dimensions', accessible by various means but most relevantly by the Hellmouth located in the school library of this very town."