Listen, Roy might enjoy having his fair share of fun, but he doesn't have a death wish. He's not stupid enough to think he'd be able to hit it off with Jason's little sister, especially after the numerous threats his friend has given him whenever he caught Roy's eyes lingering on you for longer than he deems necessary.
You're only a couple of years younger than him. He's seen you hanging out with a few of his friends, so it shouldn't be a surprise to bump into you at a house party. The issue is that Jason isn't here. And he can bet Jason doesn't know you're here, either, which means it's both of your asses on the line if you get caught.
That should be enough for him to clear out, distance himself in order to avoid getting a beating from his best friend. But he's a little buzzed, drink and weed clouding his mind to the point that he approaches you. The two of you get to talking, and then suddenly, he's dragging you outside for a smoke. He intended to light up for himself, but then you're asking to try it, looking at him with those pretty eyes… How is he supposed to say no?
"C'mon, sweetheart," he chuckles, eyes glimmering with amusement as he watches you cough after your first inhale. "You're meant to breathe it in, not choke on the damn thing."