I am watching this thread because it is interesting XD  I have to say that I really like Smile's suggestion regarding Blood Witches and Devil Children; it would make for a more interesting line-up if there are more hierarchies in the witch/warlock society.  Also, would it be possible for a child of magical parents to be born without powers?  I was planning to make a character who functioned as a keeper of a witch coven (in that, he cleans and does the menial chores) but he has no powers.  Or, something to that extent.