Maybe they remind you of the good old days.

Something similar happened to me a while ago. I replayed an old retro game, and there were some *ugly* characters that my big brother used to tease me by saying I resembled them. That led to an argument or fight between us. Now, as an adult, replaying the game fills me with nostalgia whenever I see these characters. Eventually, two of them even became my favorites.

There could be other factors though.