(Spoilers for Persona 4 follow) I don’t know if it’s canon and I don’t think it was addressed directly in the game, but I like to think that Teddie was a Shadow born from the thoughts of a young child, specifically Nanako. I know they said that she didn’t have a Shadow while trapped in the other world because she was still too young to have a serious identity crisis, but I think it also makes sense that she’d just have a Shadow that wasn’t tainted by as much darkness and inner turmoil as an adult or teenager’s. I feel like there’s a connection between Nanako’s enthusiasm about Junes and the fact that, of all the places you could have entered the other realm from, it’s the TV at Junes that ensures your safe return with the presence of Teddie since Nanako’s positive thoughts are concentrated there. It’s also telling how Teddie ends up being Junes’ lovable mascot, and how, unlike the normally corrupt Shadows who take away life from their host, Teddie ends up returning life to Nanako if you achieve the good ending.