I've googled and it seems the only way I "should" be able to turn others into vampires is via choice, and yet several NPCs I've drained the plasma of (one of which was as recent as the same night) have become Vampires. I've not chosen to turn them nor am I running any mods. Vlad accidentally died near the start of my game (didn't know he wouldn't enter my starter shack with permission and burned to death) so it couldn't have been him, unless it's his ghost which I prominently keep his urn on his mantle after purchasing his then-vacant home. It may be important to note I also "Woo-Hoo"ed both of them, if that makes a difference. Could it be because it was in a coffin?
On a side note, either they happen to be hanging around me at night (possible given my character never sleeps) or they are immune to sun damage. Figured since they were hanging around my house I may as well use them to snack on, but if this is an issue which Google had failed to point out I may need to go strictly vegan and/or deal with all NPC vampires to ensure there can be only one.
I'd planned my vampire to be a crime lord by now, but it seems I've ended up becoming something of a Marceline with the reapers guitar.
