Board Thread:General Discussion/@comment-24.52.159.247-20160217032300/@comment-6881629-20160217101142

If you look at Galmar's bugs list he can apparently become aggressive if you have a bounty, it's says Whiterun but just in case make sure you no bounty in any of the holds. Otherwise if a npc is attacking you for no reason you could try leaving them (and the area thieir in) alone for a few days.