Chapter 4 of thewholeofthemoon's Harry Potter and the Two-Way Mirror

Series Summary:
A re-telling of GOF in the Hope's Cottage AU where it was not the Full Moon that night in POA so Peter Pettigrew was brought to justice and Sirius was exonerated. Harry Potter moved in with Sirius Black and his former professor, Remus Lupin, the summer after POA and is now entering his fourth year of Hogwarts.