In the first time i did not like Fenris, nor his apperance, and nor his dramatic expressions. I found him tiresome. My absolute favorite was Anders. I had always choose Aveline as warrior. Later i tried Fenris, and I loved him. Why? For example: although he hates Anders, he refuses to betray him. (Anders would gave him to Danarius without remorse... i tried...No, I finally did not pass him Danarius...)
"Sebastian: It's our duty to tell the templars. Fenris: Then why haven't you done it? Sebastian: I guess I was hoping they'd come to it on their own. Fenris: And then you wouldn't have to betray Hawke's friends, right? Sebastian: That's not reason enough to allow a maleficar to walk free. (If Anders is in the party)
Anders: You think the templars don't know I'm here? They just haven't caught me yet. Sebastian: Which of us should do it? Shall we draw lots? Fenris: Uh-uh. You want to turn them in, you work it out with Hawke."
I like him for his loyality, and yes, his humour.
Friendship romance with Fenris is more imaginable, but i tryed rivalmance without hurting him (based exlusively on Hawke's mage-fury), and I found this to be acceptable and beliveable.
Anders preserved friend. This Fenris must be accepted. (Later maybe Anders will be executed... or not... and Sebastian can go to the abyss with his army...) I still like Anders. (I like his story, character, and understand his anger (I have inner-"Justice" too – just not as aggressive).