Rook is very interesting, and I like the concept. My only question is as follows:

Say he copies Hannibal, does his weight remain the same (because Hannibal is around 800lbs) ? And if he does, does that influece how long he can keep up that form without exhausting himself?

Overall I like your character, and he checks out in my book. Im just curious on if there's a mass limit (like only taking shape to things his weight or less), and if not does he compensate for the lack of mass with his own bodily resources?