Dean was a little tired and sore from a hunt, and he had a fair few bruises and a scabbed over scrape on his jaw but he was in a good enough mood, and condition, to be out in the yard working on cars. He had music playing from the radio of the one he was working on, and while he was used to working in Singer Salvage Yard, he'd never be comfortable with it when he knew Bobby was dead and wouldn't be coming to bring him beer or a sandwich or some surly comment about something.
He heard the glass shatter and lifted his gaze in that direction. His hand was on the shotgun filled with salt rounds before he even realised it and he headed for the source of the noise, lowering the barrel of the gun when he saw the trenchcoat.
"I thought you were a demon, I almost shot you, dammit, Cas." His tone wasn't angry, just full of relief he wasn't suddenly at the center of a demonic onslaught.