There's really two ways that Sirius can approach his situation, treating everyone as a potential enemy or being polite. Considering his innocence and that he's had some time to think about it, the latter is likely more effective. He doesn't want to arouse any more suspicion than he already has. He keeps his wits about him though.

"A few things. The portraits at least."

It's hard not to be reminded of his own family in a place like this.

"But no, I don't think we have, miss..."