I dont think i have ever seen a character with such expressive eyes. Fenris speaks a whole lot louder with his expressions than his words. I understand everything he is feeling just from a look so its strange to me that other characters find him hard to read. People dont know how to listen unless you yell.
You know the whole twin au that's going around? Well, just picture Felix getting a crush on Marinette, because she's being nice and kind to him and doesn't have a motive.