I just had an experience with the Companion's glitch in which Vilkas thinks he's a guard, notices you have a bounty and runs up to arrest you with weapons drawn, but alas as he has no guard dialogue all he does is force an ordinary conversation on you again and again and again. Yeah I know, a pretty common glitch, but I still felt this experience was worth sharing as it began not in Whiterun where the Companion's live, but in the Reach as the random encounter generator decided to have him and Ria kill a Sabre cat together. Not to worry, thinks I, I'll just get rid of him. So I start sprinting, cross a river, climb a few mountains and eventually reach my destination of Valthume. So I start talking to the ghost about the terrible evil about to break out and what we can do to prevent it... ...And then Vilkas opens the door because it was really important he tell me: "You're a talkative one aren't you?" He followed me halfway across the Reach to tell me that. I had to reload because he wouldn't let me talk to the ghost about the terrible evil, rushed through the dialogue in about twenty seconds and raced into the dungeon. Vilkas eventually caught up to me and had to be console code killed to make him shut up and leave me alone, but he managed to kill an awful lot of monsters before he reached me.