Story Cafe

It really could be open to anything. You might want to think about whether or not the person being taken over is actually kicked out of their own body or if they coexist but have lost control. The idea of it being souls that are taken over and not consciences makes it seem like you looking at this with some religous idealogy. If that's the case maybe looking through some different religious stories might inspire you, be it from the christian faith or any other. Do a little research behind it and may be something will inspire you. It's hard t give any more adivce than that without more information. What's the tone of the story? Do you want it to be a epic action/adventure type or maybe something more comical? Work on developing a charcter and a life for them and then think about how being possessed by another person would cause conflict. Good luck!!