He doesn't realize he visibly perks up until Tony grins. "You like this song? JARVIS, make it louder." And it's already loud enough to feel like an assault, but somehow it doesn't actually bother him; Bruce just laughs, leaning back in his chair and letting the music vibrate through him, waking him up. Too-late nights and too-long days and finding ways to startle yourself awake aren't exactly new to him, even if he usually has slightly more healthy routines than Tony Stark (but everyone has more healthy routines than Tony Stark).

This, though -- the shouted questions over too-loud music and stealing sips of each other's drink and someone peeking over his shoulder -- this he hasn't had in a while. Ever, if he's honest, and it's not just because Tony Stark's lab is not quite like anyone else's lab; he's had friends, even friends at work, but never this level of easy camaraderie before.