Well... There's still a lot I don't know. I'm just a novice, as far as being a vampire goes. The way it was explained to me, though, is that "vampire" just means any kind of blood-sucking monster. A Dead Apostle is a vampire who started out as a human and got transformed somehow... Um, like squares and rectangles!

I guess you could think of it as something like a virus. When a Dead Apostle sucks the blood of their victim, it's possible for them to pass a little of their own back. If they do, the blood will revive that person as an undead monster. There are some Dead Apostles who used magic to become the way they are, too, but I don't really understand that as well...