Initially Gabriel had mostly agreed to join the the Winchester's and his brother to prove to himself he could still have at least a little bit of fun. He hadn't dressed up, although when he'd initially seen Sam he'd wondered if he'd missed the memo and should have. He'd only just started feeling more like himself after Asmodeus shortly before Michael had ganked him so suddenly being alive again felt a little like starting over. Gabriel didn't have quite the same uphill battle, but still. He'd always been pretty damn good at masking most of his real feelings but the sad and curious glances Sam had shot his way now and then as alcohol made him less guarded made him wonder if he was more out of practice than he thought. The last thing he needed was pity. Mostly because he didn't deserve it but especially because he never wanted to play the victim as his crutch. Lucifer had a mess of their family doing that and he wasn't interested in walking down the same path.
The casino was pretty fun, at least. Pretty people, booze, and gambling was right up his alley. The old him would have probably picked up a cocktail waitress or two after cheating his way through the tables before the evening was even finished but he was content with his usual brand of flirting and just absorbing the atmosphere around him. The company wasn't all bad either even if he was reasonably sure that Sam was the only one who had pushed for his invite. He still had a soft spot for the kid, so declining had never been an option anyway. Having something to do was also a lot better than being idle.
As a bonus, drunk!Sam was pretty damn amusing. He'd exploited Sam's guilt for the appropriate amount of drinks for himself but nothing to extreme. If he really wanted to rage he'd just find some time for himself to take advantage of the endless bar he'd been told so much about. At the moment being sober was far more entertaining. He'd lost track of when Castiel and Dean had drifted away at some point. Maybe while he'd been throwing down at that Texas Hold Em' table. Regardless, he wasn't leaving a drunk Sam to his own devices in a place with so many ghosts. He'd felt them ever since he'd arrived and just because they hadn't seen them get all murderous yet didn't mean they might not.
"Sure, Samsquatch. I'll relieve you of your parental responsibilities a little longer if you want." He smirked, and made sure to put a steady hand on Sam's back as they made their way through a particularly crowded portion of hallway. As much as watching him tumble might have been amusing he didn't actually want him to get hurt.
"I'm pretty sure you don't need to find another bar and if we do find a pool you are so not getting in. Your brother would probably find a way to kill me again if you drowned. Do you really think we can out creep this creepy place?"