Sam needed to be here with Dean just as badly as Dean needed to have that bottle sitting in front of him. He was worried. A person didn't just up and lose over a year and some change of their life and walk away perfectly okay. It was probably a difficult enough situation for normal people who went through it. To think of how incredibly frustrating it had to be for Dean - who was finding out that various members of his family were back from the dead while the Apocalypse was rearing their way after having been murdered - made Sam wonder exactly how much Dean could actually take. That was part of why Sam had insisted on spending some time with him. The other part was mostly centered on the simple fact that Dean's killer was still out there somewhere. Sam didn't want him running around and doing too much on his own until they figured out who was responsible for placing that bullet in the back of his head. And judging from the way that Dean was going at that bottle? It was probably for the best that he stuck with Dean anyway. If his killer came back for round two, Dean probably wouldn't have been able to so much as lift a finger to defend himself. Not if he got himself stupid drunk, which Sam was kind of counting on at this point.
Another thing to concern himself with. The drinking wasn't new. When Dean had first gotten out of Hell, it seemed that was what he had spent a majority of his time doing. But that had been a year ago and, since then, Dean had progressed a tiny bit. Now it was like he was fresh from the pit all over again. Sam ran a hand over his eyes, the other gripping at his own drink. He was drinking a lot more slowly than Dean was, pointedly doing so in order to ensure that at least one of them stayed sober. Designated driver would be his excuse if Dean pressed him about it. It was a good excuse. One that Sam didn't think Dean would really question - after all, someone did need to make sure that they got home in one piece. If they had been going out for drinks like they used to, then the designated driver thing wouldn't be an issue. Going out for drinks had once meant a couple beers, easy. Now...Sam eyed the bottle in front of his brother warily, then dropped his gaze down the neck of his own. Whoever had said that change was a good thing could take that quote and stick it right back up their ass.
"You haven't gotten any memories back yet?" Sam inquired, pushing his drink aside. He wanted to talk. To make sure that everything was okay, even though he knew that things were far from it. If Sam knew Dean, that was probably the last thing in the world that he wanted to do right now. That didn't mean Sam wasn't going to try and check up on things anyway.