Okay but what if Sam and Dean didn't regularly talk early Stanford era? What if there happened to be a case at Stanford, like on the school's grounds. What if one sunny California afternoon, Sam is killing time with some of his friends at the art museum on campus and he turns a corner and thinks he's dreaming or lost his goddamn mind because there's Dean. Dean in a fucking art museum. And it's so ludicrous, so ridiculous, Sam just kind of stops for a second.
The guy he's looking atā Dean, because he knows it's Dean. Could never mistake or not know from any angle after any amount of time, Deanā turned away from him, staring with an intent Sam immediately recognizes at some art piece. Immediately knows it's a case. Instinctually begins running through any and all possible relevant information. Within seconds Sam recalls he does know the artist, that they died recently. He knows where every camera is. He knows the security guards, some of them by name. And that jerks him to a stop, because this isn't some case for him. Sam is known here. Dean is not. And that could blow Dean's cover. It could blow up Sam's entire life here.
So Sam does a crappy job of it, but he manages to balance keeping Dean in his peripherals while not drawing too much attention from his friends. He knows Dean's seen him. He knows Dean knows what he's doing. He can, peripherally, see the way Dean's smile has in some ways lit up, and in other ways gone mechanical. He can see the second Dean is able to cut his conversation short, and makes up some reason to excuse himself from his friends.
He knows Dean follows him like a shadow, trusting that Sam knows where to go for a private conversation. There's a side entrance and patio area that isn't at all private, but has a blind corner they can talk without being filmed and not be suspicious about it.
Sam helps Dean get in and out that night and gets the job done. Of course he does. Dean insists on their being no chick flick moments, and it drives Sam up the wall. There's so much Sam wanted to say. He's somehow even less capable of saying it now than he was before, because now he's aware of what he has to lose now. And he knows, deep down, that if Dean just fucking asked him, he'd break. He'd ditch Stanford and his friends and his apple pie life in Palo Alto if his big brother only asked.
But Dean doesn't do that. In fact, in hindsight, Dean seemed. Well, Sam isn't really sure how to describe the weird mix of emotions Dean insisted on bottling up. But he didn't ask Sam to come home. Was cagey about John. Almost seemed sad. Almost, maybe, seemed a little happy. Sam probably imagined this entirely, but Dean almost seemed proud of him. If it was all buried under about twenty years of sarcasm and deflection and macho bullshit, that is.
It didn't have to be their last conversation. Sam knew that. But it felt like goodbye anyway. It felt like the best goodbye they could bear.