Severus laughed and finally turned back to Sirius. "I insulted Lily before he tried to figure out what I was doing staring at you." He ripped open his collar. The bruises had been barely hidden by the cloth. "Or figured out who gave me these. Potter--" Disgusting, terrible, annoying Potter!-- "is a devastatingly clever boy."

Sirius was a bit dense. He went off to have fun knocking boots around the school and Severus got himself punched senseless to protect him.

"You think I came up here to be fucked, Black. And you're wrong." Well. Not really. Severus just needed his tantrum.