Sharing this here as I fiddle with it, feel free to chime in with comments. For eventual working up into an article for Threshold. There is a risk I might go TOO nerdy with the microbiology, so hoping y'all will restrain me.
The Strange Vampiric Bloodlines of Mystara
by Cab DavidsonFrom the Journal of Averyx, Immortal of Time, Finder of Lost Gods and Scholar of the Mysteries of the Multiverse
What is Vampirism?
Vampirism isn’t just about being undead. It is much worse than that. Vampirism is the synergy of deadly disease and the curse of undeath, and it is the most perfect form of living entropy. But that’s perhaps an overly poetic way of describing what is actually a very, very simple living thing.
We don’t entirely know how or where in the multiverse vampirism came about. Yes, I know, we could find out, but we’ve come to a sort of gentleman's agreement with the Entropic chaps not research it. Sometimes our schemes go awry, sometimes theirs do, and perhaps it is enough that we acknowledge this and work within the new norms that these cockups create rather than go back and try and clean up the mess.
Most diseases come about on their own without any immortal help. They’re either caued by how living things live, how they age, or more often by tiny living or almost living things around them. Cholera, goblin pox, the common cold, harpy clap, these are examples of diseases that came about by entirely natural processes. Lycanthropy in all of its myriad forms did not, it was created by human mages “playing god” (and why not, I say, that is after all in the finest traditions of Alphatian wizardry!). But vampirism seems to have been created by an immortal, it has specific traits that cannot be formed of mortal magic or science.
To get down to specifics, vampirism is caused by a virus. I shan’t bore you with the specifics of how a virus works, but its sort of like the smallest of animalcules, the smallest, swarming forms of life, but simplified to a point where it can only exist in association with its victim. And quite uniquely it exists in a form that touches not only the body of its victim but also the link between that organism and the entropic forces that link the soul of the victim to the time of their own death. And the result is catastrophic – the victims soul can no longer enter Limbo, it is bound to the body and merely killing the body no longer severs the link. They cannot die, but they are no longer ‘alive’ in terms as would be recognised by any creatures of the positive planes either.
And thus they are stuck between worlds, trapped by a metaphysical virus in a strange existence that deprives them of any normal means of sustenance. To exist they must still feed, but being neither alive nor dead they need to tap in to the very essence of living things to do so.
Like most viruses, the vampire virus (Orthohepadhavirus sanguinum, if you must know) has a limited range of hosts. But on occasion it may infect creatures that perhaps are not associated with vampirism. And being such a strange virus, one that exists in metaphysical as well as physical space, the list of creatures that can be infected is more broad, more complex, than anyone would have imagined. I shall outline the means by which these infections occur in various new hosts, and what the implication of this is, presently.