I can never get into the whole 'drown the world in blood' thing with Anders. It makes me want to go, 'okay, chill dude.'
As to the Fenris romance on the friendship and rivalry paths...I tend to lean towards the rivalry path simply because I love how it plays out. I agree that it seems a little more appropriate as a mage to rivalmance him, but in my current walkthrough, Temperance is trying her best to make everyone happy and is Fenris's friend. She doesn't see some of her actions as being anti-mage; she honestly believes that mages need to be taught to control their powers responsibly. Despite the many atrocities committed by templars, the Circle has helped mages.
Now Samia Hawke, my rogue, loves making mischief for Fenris. She's the sort of person I can see sneaking into Fenris' mansion and putting bright decorations all over the place, maybe prop up the dead bodies to look like they're in the middle of a dinner party. She does not agree with the Circle, thinking that many many improvements can be made. I actually think she's trying to see how many times she can get on Fen's nerves before he pulls out that lovely white hair of his XD
I have a question, however. During 'A Bitter Pill' after he kills Hadriana and asks what has magic touched that it does not spoil, does Hawke make any remark if he/she is a mage? I've played the part several times, but never chose one the options that may bring it up, and I'm curious.