[Sirius drapes an arm over her calves because, well. Why not? If she's going to invade his personal space, it's going to happen right on back.]

Shaking in my knickers, Tonks. [Part of him finds it amusing, but mostly there's just part of him that thinks that, no matter how terrifying she is, Molly is no Azkaban. Then again, Molly is tangible. That's terrifying.] You a bad influence on me? I'm surprised she hasn't yet confronted me about corrupting the morals of the youth. [No wait. That's actually happened. Carry on.]

Were you clever enough to keep it hidden from them? [Because that would be a damn bloody tragedy.]