phantoms lines to fill for this slayer who is on a course towards self destruction.
Someone she's gotten 'involved' with who is a supernatural species of some sort who she probably should have put down but for whatever reason she won't/can't. (I have some wanted PBs for this particular line)
People she's tracked and then let go instead of killing like she's supposed to.
Someone who knew her before she went off the rails who she hasn't seen for a while to maybe try and get her back on the straight and narrow.