y'know, i don't think there's any possible nicknames for Winter aside from one that's a very bad idea

@azushark One could go with Winnie. I hope that's not what you were thinking of since I'd have no idea what would be bad about it... (personal taste aside)

If they happen to be the right colour they can be Winnie the Blue for extra obviousness! :3

(Also I should make a list of characters like you did.)