I really like the peter pan idea, conceptually. But I don’t want Peter Pan to be the grown up August, with a BEARD. That is just so wrong! The real Peter Pan would be horrified just to loose one baby tooth!
So I’m leaning more toward InfinityPalm’s Baelfire theory, which I must say is very well thought out! I really like that one. The only questions I have are 1) how do you explain his age only changing a bit over so many centuries and 2) why exactly would Baelfire escape to our world?