A quick shadow of confusion passed over James's features. He had vague memories, of course, of waking up, next to Regulus. Slowly, it came back to him that he was not seventeen. That they were not at Hogwarts and that James was not dating Lily Evans. He was married. To Lily Potter.
"Must have been terribly disorienting, seeing as to how you're usually the one running off in the middle of the night." Incidentally, that hadn't been anything near what he'd intended to say. Sure, maybe it was true. Regulus had done it for months-- years. Though maybe it wasn't the time to ponder the length of their... 'interactions.' But it had always been Regulus who slipped out of bed, fleeing the Gryffindor Tower just as soon as he could. Never mind that James had been as brilliant at wards as he had been at everything else. But surely, he was leading himself away from the point.
"I was still sloshed when I woke up-- it's a sodding miracle I made it home. What were you expecting? That I'd snuggle on the beach with you all evening?" Really, Regulus constantly-afraid-of-getting-caught Black was in a huff because James had gone home? To his wife? And besides, what would he have said? No, James knew himself. He'd have just taken Regulus up on his offer. And he could hardly even have blamed his drunk self; Regulus had gotten rather clever with that mouth of his.