The brief delay before the door opened had Dean even more on-edge than he had been, torn between slinking away, and kicking the door in to make sure nothing had gone wrong... which was a slightly irrational response, probably, since he didn’t even know the kid, and he didn’t think anything could have gotten into the complex, but it wasn’t like Winchesters and those close to them didn’t often get themselves in trouble, or anything. Plus, he’d already been killed once before, which meant ... well, it didn’t actually mean anything in particular, but it wasn’t like it was completely unlikely that something had gone wrong.
Not that he was sure he even cared, aside from he’s a person, people shouldn’t be monster chow, because for all that they were related, he had no actual connection with the kid. Which was the whole reason this was going to suck out loud.
Anyway, that didn’t matter, because Adam opened the door quick enough that Dean hadn’t done either of those things, just shifted uneasily in place for a second while he tried to decide what to do, and he offered a bright grin that probably looked mostly genuine to anyone who didn’t really know him. It was the kind of smile he often used on-the-job, all acting - but he was good at what he did, so it didn’t look as fake as it was. One point in his favor, but not many others, because unlike Adam he didn’t even have anything basic to say, just an awkward “Uh, thanks,” that was practically a mumble as he moved inside.
...right, inside and now he had no idea what the hell he was doing. He wasn’t used to things like this; it would have been easier if they’d been somewhere else, out in public - a restaurant, or a bar, or something. Then he’d be able to be a little more relaxed, a little less feeling like he was walking that thin line between intruder and guest, both roles which he wasn’t very good at playing.