I'm trying to do the Dawnguard quest "A New Order", and am currently trying to recruit Gunmar. I located him near Clearspring Tarn, but he is insta-aggro on me. I wasn't sure if this was part of the quest at first - perhaps I need to defeat him to get him to talk? Prove my worth in combat or something?

But that didn't work. Trying to yield to him didn't work. I can't Calm him. I can't get him out of combat to talk to him in any way. He's locked on aggro on me.

I haven't seen anything on UESP about him being bugged.

I'm on X-Box 360.