https://www.youtube.com/watch?v=uaZReXrzj1gSaw this video uploaded to youtube, and I definitely buy into it more than any other theory.
His explanation for why Aang appears the way he does, absolutely lines up with why I thought Aang was the kind of parent he ended up being.
I criticize LOK for a lot of things, but I thought the way they portrayed Aang as a parent, was extremely realistic and well thought out considering his character in ATLA. But I think this video explains it better than I ever could.
I definitely recommend you watch this video.
The theory that Avatar past lives appear how they were, at what they view as the most significant moment in their lives (Video)
