Let them obsess with whoever they want. If you don't like it, don't talk to them.

I'm going to get hated on for this . . .
I dislike it for my own personal reasons, but I suppose I can't change anyone's opinions.

^ You're not alone, I find it just dumb

To an extent... Obsessing can be either simply: "I adore *Character X* so much! He/she is awesome!" or "ASDFGHJKL DO NOT TOUCH MY BABY!!!! THEY WILL KILL EVERY OTHER CHARACTER IN EXISTENCE!!1!" The second one is kinda... meh, especially when you know more about the character than the other person (like that one chick I met irl that was all like "I know more about Lelouch than anyone else evar!" and couldn't even name 5 other CG characters.)
However, if you're tactful and decent about your obsessions, then yeah. I liked Junko Enoshima long before I watched Danganronpa. She's not my favorite from the series now that I'm watching it, but still. If you want to love a character, go for it. But for the love of Alchemy, don't say you know more than anyone else.

sorta? its okay to say.... "I think I'd love the character if I watched the show..." but downright their amazing without even at least a clip. I like bojiggler from bobobobobo (don't know how to spell the show's name) because I saw a clip but I don't have the slightest inclination to watch the show