I dunno. Go write the fanfic.
Go watch old episodes and find what separates 9 from 11, and see how they interact with Amy.
Actually, I do have something less meta to say: no fish fingers and custard. 9 knows what he's doing a lot more than 11, even at that point, so he probably jumps straigh to investigating the wall.
edited 4th Oct '11 4:39:41 PM by Yej