Personally, I don't like it when Snape is forever calling Lupin 'wolf' in an insulting way. What's wrong with calling him 'werewolf'? That's a worse thing to be. I don't get it. It seems off for Snape to be inaccurate like that. As for canon, I don't remember him using either. It's been a while since I read all of canon, though, but obviously the slur didn't stick in my brain, one way or the other. I prefer Snape to simply use 'Lupin' in a way that suggests something one would scrape off the bottom of one's shoe. And then they fuck. *g*