Dean watched Sam carefully. His brothers movements seemed more frustrated. Antsy. Shakey. It was on the tip of Dean's tongue to comment but he reminded himself that getting into an argument with his brother wouldn't be the smart thing to do at the moment. Sam was right. Neither knew how long the demons would stick around and making a move on now would be the smart thing to do. Grilling Sam. They'd have time for that. Maybe.
Yeah. They would. Because no matter how bad the feelings were between them. How busy things got. How worried on other things Dean was ... Sam was a priority. Sam was important to him. And as suspicious as he was, and angry as he was ... irritated with his brother. He was really, very worried. Getting involved with a demon was tend kinds of stupid. But this, Dean suspected was different. He wouldn't be surprised if it was something directly involved with Lilith and something that Sam would probably come to regret, if he didn't already. Because that was what they did. The stupid stuff, so the rest of the world didn't have to. To make sure that the rest of the world came out alright. To make sure that one of them, if not the other, made it out alright.
Dean followed Sam around the side, entering and keeping to the shadows when they made it into the building. He walked a little away from Sam. Not too far but straining to get a better sound. His current position at a point where he could step in front of Sam - what it was automatic thinking - if need be or veer into another direction to hide behind something, and choke the enemy as they made their way out.