"So what if we sparkle? At least we're fucking fabulous." --One incredibly fabulous Vampire.Vampires, which surprisingly enough don't sparkle, are a disturbing and mutated by-product of a parasitic worm having taken residence in a person. No known cases of vampirism have been observed in Nymphs or Beast-races. This presents itself as interesting, as all species of man and elf can contract vampirism. At present, it is unclear as to why this is the case.
The Parasite Edit
These worm-like creatures are long and thin hemophages, feeding on the host's blood. Under normal circumstances, this would be an incredibly unsustainable process, killing the host rather rapidly. Somehow, these worms have developed a way to counteract this, mutating the host to suit their needs. This is why vampires drink blood and seemingly cease aging all together upon finishing their transformation.