Severus bared his teeth in a soundless sort of sneer, fingers flexing into fists at his sides because it was a better option than going for his wand which he knew beyond anything else was in his belt. That he had it was enough for now — it was possible to use it if need be. Sirius would probably deserve it.
Later though.
“Oh, I’m sorry, Black,” Snape said his name like ie was an insult, focusing his attention on stepping away again — this time with more intelligence, testing where he could and could not be in this room without the painful pull returning. “By all mean, you keep laying there like the useless blight you are then, because that’s obviously just as helpful.”