I did the main questline for the Imperials. I am the hero of the Empire! I was walking by some lady's farm and saw a Stormcloak going against an Imperial. I didn't want to get involved since I've gotten my share of blood, so I just watched. I noticed the Imperial was taking a beating, and went down. So I whipped out my Healing Hands spell and started healing him. He got back on his feet and came back. After a few more bits of healing, he killed the Stormcloak. I wait for a few hours because I needed to talk to the farm owner. I wait about three hours. When I come to, the very same guard is all "OMGWTF WHO DID THIS??!?" he then proceeds and forcegreets me and asks if I did this, or if I saw what happened. I told him no, I didn't know what happened. So he keeps patrolling around the body all inquisitive-like.
Seriously, what's up with that? You killed the guy, idiot! I helped you kill him, remember???