Sirius had been only half focusing on his work, and after a quick Nof from Roxanne followed Peter out of the classroom. He wanted to believe that Peter was just here to say hi, but he wasn't an idiot and he knew Remus likely told Peter. So Peter was here to check up on him. He would have been annoyed by it if he could find that emotion. But he was operating solely on faked enthusiasm and didn't have room for anything else.
"You know me and sun," he said, walking with an extra swing in his step. "How was your day?" He knew Peter didn't technically have a job right now. "I hear that whole department of mysteries thing is getting off the ground. That's great! Did you get to talk to Padma?"