why not both? while its using the same black zodiac from the movie, a) they don't have to be ghosts and b) they can be any species otherwise. bobby's a wraith possessing another host and ~witheredlover is a living, but cursed human. the only requisite is to somehow fit whatever your choice zodiac is (bobby is the torn prince thanks to being cut apart in death and ~witheredlover got left at the alter).