Scorpius was taken completely by surprise at the kiss. Which was kind of pathetic, considering how she'd been coming on to him in the kitchen (not that he'd been any great observant person in there. He'd been so oblivious he didn't realize she came onto him at first). He responded to the kiss, though it landed halfway on his lips and halfway on his chin, and returned it out of sheer force of habit. It probably said something about him that the alcohol on her breath didn't really register with him.
"Woah..." He said when she pulled away. "Okay, that was... weird."