"Because there are much worse people to be spending detention with. Trust me, I'd know," Sirius said, tossing her an amused look. He shut the transfiguration book he'd been flipping through and sat it on top of the shelf.

He hummed, shelving another book that was part of his stack into its correct place. "Being a wanker is part of being a Black. It's our first lesson, in fact." Sirius picked up the transfiguration book again and walked over, sitting down in a chair close by her stack. Is he deflecting? Probably. "I just know I'm the reason I'm keeping you away from your studies."

Although he said it, Sirius wasn't going to deny (if only to himself) that he liked spending time with her. One on one and without James around.