(There are also spoilers in this reply!)
It is worth noting... once you beat him, you have several options on how to deal with him.
He remains /quite/ pissed off at you if you fuck him, a fact he makes extremely clear... but mellows a bit if you have a joint jerk-off with him. The tone is very different and could conceivably result in him being more for realsies friendly in the future despite you beating him.
I really /like/ that interaction as it's so clearly fitting with his personality. He's a lot like Logan in that respect - he has emotional baggage he's carrying with him and doesn't really want to open up, but if you're willing to put in the mileage, then just maybe...
Definitely true - I didn't mean to imply that he and Logan were the same, haha. Nor that Gunnar is the most, um, stand up moral individual :P
But hey. Maybe Gunnar just needs someone he can actually trust in!
(Or, alternately, maybe he's just always going to be a jerk, haha)
(Also I'm curious what precisely his connection to Scar is, haha, but that's neither here nor there at the moment.)