Severus bristles visibly at Sirius's laughter, and his determination to end this and leave waivers. Rage squirms under his skin and he knows it would be easy, so easy to do any number of horrible things right now. Sirius doesn't look quite seventeen anymore - and there's no sign of James, so he questions the Potter boy's information (surprise surprise, a Potter being an uninformed idiot) - but he can tell that's where his experience ends. He can feel it, the lack of finesse, of war-honed practice. For a moment, glaring with enough vitriol to make some students burst into tears, he imagines not making him hurt or bleed but grasping his mind and making him leave politely. That, he thinks, would sting the worst.

"Somehow your offer seems less sincere than your godson's," he spits, spiteful, and knowing that the idea (even a false one) of Snape being friendly with James's son is going to piss him off - not caring if he gets hit again for it. Not caring, either, what Sirius knows and doesn't know. "I'm not going to give you the satisfaction of anything. Go find your playmate, I don't give a damn."