After Jessica's death, it was difficult for Sam to come to his senses, but Dean tried to help him with this. In his own ways.

"Come on, Sammy, let's go!" — Dean stopped the Impala at some second-rate bar, drumming his fingers on the steering wheel, already figuring out how his night would go. "Dean, I've told you a thousand times, you dumb oaf. I don't want to." — Sam said so flatly. He looked out the window and squinted. "What.. What is it?" — Sam stared at a figure hunched over a body around the corner, where the streetlight didn't reach. "Huh?" — Dean tried to see what Sam was looking at.