Aside from one broken quest early on, I've actually had a pretty care-free time with skyrim (360 for those asking). Sure dead dragons have a habit of falling out of nowhere and I can run around with a stuck arrow in head for a week. But nothing really bothered me, until...

I beat the main story line and as a good way to wind down I decided to have my character get married. I knew I wanted to wed Aela from the Companions for a sure, so I marched over there with my amulet of Mara. (Now, to clarify I had completed their quest line a while ago) I get into Jorrvaskr and start looking around and Skjor greeted me at the banquet table. I flipped my shit screaming "DEMON!", because if you decided to not heed the spolier warning, Skjor dies fairly early on in the companions missions. Yet I'm gazing upon a man returned from the dead, even did a quest for him, hah!