It was a theory that a barber surgeon in Paris had, that you could change a man's temperament by giving him the blood of something else. Say you had someone who was angry, who couldn't be calmed by other means, you could drain their own blood from them and replace it with the blood of a lamb, and they'd take on the attitude of the lamb instead.

It didn't work that way, of course. But the Renard branch of the family - one of Leon's daughters. Returned to France. Family of her own, all of that - they were interested in it. Thought that because turning is a process that begins in the blood, and because only humans can be turned, perhaps the risk of turning could be averted by filling someone up with blood from a cow or deer. An animal that doesn't hunt. It didn't quite work. It did make that side of the family really fucking weird.

[ Look he's not going to say that the Belmonts aren't weird about dogs. But at least they're not also weird about literally all animals. ]