By the way, I thought of a slightly different origin story for vampires. (Though they can still turn others.)

Vampires are humans that have been 'claimed' by the devil. He usually picks people that have a high potential for evil. These humans will live their lives as vampires, until they are deemed 'ready'. At which point they will 'die' and be reborn as a new demon in hell. Sound like an idea? Or should be stick with something more standard?