Harry Potter and the Prisoner of Azkaban · Chapter 21
Lupin Resigns and Sirius's Farewell
Lupin resigns after his werewolf secret is exposed; Sirius sends Harry a letter confirming his safety, revealing he sent the Firebolt, and offering to be Harry's guardian.
Outcome
Harry gains hope for a future with Sirius; Lupin gifts him the Marauder's Map before departing.
