@Carl867 I see, like I said it is an interesting concept, I just recommend you try to figure out what direction you want to take the story, also how would the Doctor feel about there capabilities of dimension hoping. Also think about how you are going to integrate your characters into the story will this Y/N be just as capable as any other or as much as C-132? Also a recommend not to have you characters overshadow the original characters by making them too op. Then again it is the Doctor, and I've learned he can do the most insane things so that wouldn't be a problem, I what I'm trying to say is have a balance between your characters and original characters importance.
