Over spring break, I read the book A Brief History of Cults by Peter Haning. One group he mentioned in particular from Tennessee had, believing they were vampires, sucked the blood out of their victims. They thought that by drinking their blood, they absorbed some of their soul. I found this concept fascinating: what if the human spirit was in our blood? Would we die a bit every time our cat scratched us? Would new blood cells contain our soul as well, or only the original cells?
(I'd like to say, that I mostly just wanted to experiment with fake blood. Please don't be concerned.)