The thing James didn't understand was why people didn't prepare themselves. The people who were flat out lousy while drunk in the midst of a crisis were mere those who didn't have enough experience being drunk in the midst of a crisis. When Regulus made that... that sound, a cold wash of adrenaline crashed through his veins and along his gut. Certain pitches just resonated. The bad kind of trouble. The not so fun sort of danger, the sort that tangled up somebody else. The same way that in the Forbidden Forest, some snapping twigs rang a bit too ominous.
Conveniently, James didn't both to spend much time thinking about the fact that Regulus was being alarmed by a wave. (Though, maybe could have been a... shark. A death shark. A deathy, Death Eater-eating deathshark.) Somehow, he found himself on his feet, his hands snatching at Regulus's shoulders, dragging him in a mostly vertical direction. Or at least it felt vertical, until he was stumbling backwards. But at least he did the important thing, and hung onto Regulus, pulling him along until James found himself mostly sort of grabbing at Regulus to keep them both upright.
He was clearly a little out of practice on this drunk-crisis thing. Not to worry, though. It was like riding a broom. Just gotta get back on. Or up. Or something. Oh, fuck, his feet. One hand curled around the back of Regulus's neck, the other wrapped around Regulus's upper arm, James managed to get them both to be kind of stationary. At least, he hoped they were stationary. Because everything still felt a bit spinny. But he could talk and spin at the same time.
"Hey. Hey- hey. Hey, you're okay," James finally got around to saying. "Okay? You're all right." He paused to chuckle a bit, the moonlight making it all too easy to see how wet and sandy and mussed Regulus was. "I mean, you're a mess, but you're all right, yeah?"