Arc 19The Ravenclaw Championship
William investigated Sirius Black’s claims that Scabbers was Peter Pettigrew while organizing a House-elf delivery service and helping Sirius remain hidden. Ravenclaw won the Quidditch championship, and the students moved into their end-of-year exams.
- William concluded that Peter Pettigrew was hiding as Scabbers and later helped Hermione and Anne find Sirius, who confirmed that Peter had betrayed James and Lily and framed him.
- William and Hermione told Sirius that Scabbers had died, helped him stay hidden, and withheld the story from Harry until they could find proof against Peter.
- William organized Kiki's Delivery Service, hiring unemployed House-elves to deliver orders and arranging for Mars to train them.
- Harry and Ron helped Hagrid prepare to appeal Buckbeak’s sentence, while Hermione slapped Malfoy after he mocked Hagrid.
- Professor McGonagall punished Harry, Wood, and Ron for sneaking to Hogsmeade, leaving Gryffindor with a severe points deficit before its final against Ravenclaw.
- William scored for Ravenclaw in the final, and Cho helped Harry reach the Snitch, but Harry caught it too late to prevent Ravenclaw’s 160-point victory.
- William completed his exams with full marks in Transfiguration and Potions and finished Lupin’s Defence Against the Dark Arts course first.