I just found the weirdest glitch.
I was using whirlwind sprint to get to the Companions' Blacksmith for some buying and selling. After I was done, Farkas ran up to me with his weapon drawn. But instead of threatening me, he just had his basic conversation. I went through all the options and walked away, only for him to follow me and continually initiate the conversation.
I left Whiterun and ran down to the farms, then tried to fast-travel to Riften for more trading, but it told me I couldn't when guards were pursuing me. Well, I approached a guard, seeing if I had accidently p***ed someone off, but he just greeted me and walked away.
I turned around and suddenly saw Farkas running toward me, weapon drawn, again. And again, he kept with his basic conversation. I had to stab him before I could get away (Luckily, I didn't get a bounty for it.). I could then FT, but when I returned to Whiterun, he was at it again.
I'm thinking the game accidently flagged him as a guard, and the only way I can get him away from me is to gut him.