James was watching her from across the room, catching every little glimpse she had sent in his direction. Good. So then his knickers were doing just the job they were supposed to, coupled by his Quidditch-playing muscles. He knew he had to look smashing. He was James Potter, after all. He never looked anything less than perfect on most occasions.
But the moment she started to gulp down the alcohol, his stoic stance quickly melted away, and he sighed heavily out of disbelief. He crossed the space between them again, and placed one hand on her hip, the other gently pushing her hand down to place the cup back down. "You shouldn't do that, Lily. Trust someone with experience, you'll regret it, and I'd rather you not get that sick," he uttered, pulling her closer to him, a bit protectively this time.
Oh, he knew. Boy did he know, but he wasn't going to be stupid and try something. Not here, at least. With Lily.. he was a more private person. With any other lass, he was public about it. Why? Because he wanted Lily to pay attention. But now? Now his attention would be solely focused on her for the evening, and for all eternity for that matter.
Besides, he was determined to earn her trust back, and not allowing her to get sicker than a dog seemed like a jolly good start to him.