Reincarnation. Well, he supposed it was better then being trapped as a ghost forever under a lake, or just ceasing to exist entirely. Besides, he had some things to do that he couldn't in the after life.

In Lily's attempt to save her daughter from disaster, she cast a charm to change the baby girl into a boy. In order to keep spells from her daughter, Lilly never gave her a true name for her daughter's form, and so she never had one, until a boy in the abandoned bathrooms picked one for her.