Harry Potter and the Prisoner of Azkaban
"This house" – Lupin looked miserably around the room, – "the tunnel that leads to it – they were built for my use. Once a month, I was smuggled out of the castle, into this place, to transform." (18.36)
"Sirius Black showed he was capable of murder at the age of sixteen," he breathed. "You haven't forgotten that, Headmaster? You haven't forgotten that he once tried to kill me?"
"My memory is as good as it ever was, Severus," said Dumbledore quietly. (21.61-62)
He was thinking about his father and about his father's three oldest friends [...] Moony, Wormtail, Padfoot, and Prongs [...] Had all four of them been out on the grounds tonight? (21.259)