Well, you said he starts as 8 or 9, so, the first time would be when he's 12 or 13, and the second time he would be 16 or 17, depending on what you pick. I'd say he could sorta tell his situation is a little off because other children where he was raised are raised by their own race, and eh's the only one around with a demon for a parent. But, yeah, he wouldn't find it too weird I think. 

The only other thing I could think of is a base outline for the world he's raised on. Das classic middle ages fantasy world sounds good to me. You?