"Thanks." Crowley held the books, because shoving them into his own bag might inspire a crisis in Aziraphale. His bag wasn't exactly in pristine condition and there were rather more pentagrams drawn on it than he suspected Aziraphale might be comfortable with. So he just walked with him, arms around the two books, heading out of the school at long last.

"Crowley! What are you doing tonight?"

Based on the accent, Crowley knew it was Nicolas before he spotted him, so he wasn't overly alarmed. He doubted Nicolas would care who he was with. The other boy stood there, of course close to Spike, smoking right outside of the school. All right, maybe Aziraphale would mind this.

"Dunno yet. Why, what's up?"

Nicolas did notice Aziraphale now, but he just shrugged as he blew out some smoke. "Got a gig."