Snape stared out the window, trying not to look like he wanted to kill someone.
"You're more than welcome to share the fire with me, you know, Severus."
Snape scoffed. "My job here is done, so if you will excuse me." And he stepped out into the howling wind, but before he could even comprehend it, he was back indoors, slamming the heavy oak door shut behind him, Lupin patting snow away from his hair.
With a knowing smile, Lupin sat him down at the table nearest the fireplace, and Snape couldn't protest when a pint of hot Butterbeer was set before him.