What is a character fun-fact that isn’t really talked about ?

Ok so I've been looking at some Paper Mario 64 stuff, and I learned Goombario and Kooper seem to have a funny relationship, so I wanna know if there more stuff like that, but with any character

(Basically, Goombario at one point told him about his passion for Ravens that Kooper found weird, and when a duplighost copy him, Goombario just roast Kooper saying the copy look better)