"Son of a bitch--" He hissed out as Sam bit him, and that was when Dean decided he wasn't going to play nice anymore. Maybe what they really needed was to punch the crap out of each other, or they needed to get laid, but Dean was pretty sure Sam was laid recently anyway. Then he decided to come back to him. It was a complicated mess.
Digging blunt fingernails into Sam's bicep, Dean bit down on the inside of Sam's arm, trying to get him to jerk it back down so he could get his keys. He wasn't quite able to ignore how worked up he was getting, though.