Arc 9The Map and the Dementors
Douglas trained Hogwarts students through dangerous practical lessons while helping Sirius and Lupin and preparing to uncover the truth about Scabbers. After Dementors disrupted a Quidditch match, Harry learned about the Marauder's Map and spent his money trying to win it through George and Fred's prize draw.
- Douglas encouraged academic competition, advised Hermione on using her Time-Turner, and helped launch the Charon Detective Agency, where Draco hired the students to investigate Sirius Black's case.
- Douglas developed Wolfsbane potions with Lupin, tested a Homorphus Charm during Lupin's transformation, and trained younger students on a hazardous obstacle course.
- Harry suspected Sirius was a werewolf, but the students found weaknesses in the case against him, and Douglas kept the investigation moving while protecting Scabbers in an enchanted cage.
- Lavender's rabbit died, prompting discussion of Trelawney's predictions, while Douglas explained that her genuine prophecies were rare.
- Dementors invaded during a Quidditch match, but Harry's crane Patronus and the students' defensive magic drove them away, and Douglas questioned Fudge and Umbridge about the breach.
- After George and Fred heard that Douglas's dog was called Padfoot, they gave Harry the Marauder's Map and revealed its prize-draw ritual.
- Harry spent his Galleons on repeated draws, ran out before completing the map, and went to Douglas's office for money, where Sirius stopped Wangcai from reclaiming Dobby's pouch.