Hi, Henry,
My goodness, "about" 15 books? That's amazing. Why don't I know you? What are the titles and what is your full name?
Idea are very personal, as you probably know, Henry. I've written and published 107 books at this point, and not duplicating my characters and ideas is a real problem too!
Ideas? Well, for one thing, I think exotic pets (and you don't mention how exotic they are) can get into a lot of trouble in a home and neighborhood atmosphere that is really foreign to them. How about keeping them a secret because he feels it might be illegal to be keeping them (dependng on what they are, and if they present any kind of danger to the community.) And there can be a lot of personality in certain exotic pets, like monkeys, for instance.
Sorry, but except for that vague observation, that's all I've got a the moment. Good luck!
-----Gordon Korman-----