Roughhousing with an angel is really different from his brother, even when Sam hit his growth spurt, but Dean's enjoying himself even when he finds himself underwater. His lungs are hungry for air, but he opens his eyes when Cas starts to shake him. His eyes seem even bluer down here, which is a pretty big accomplishment, considering.

Oh. He doesn't really care about breathing anymore. He grins slowly, and then tugs on Cas's tie, half to confirm and half because he's feeling playful now, giddy, giddier than normal but who wouldn't be after being pulled out of their worst nightmare?

He slides his hand down Cas's arm to get a grip on his sleeve, and then tugs. Might as well see what's on the bottom, or if they can get there, right? And if something happened, Cas would save him. Or Dean would save Cas.