So much happened that I can't cover everything. Harry receives a Firebolt (first seen while he was in Diagon Alley) only for it to be temporarily confiscated to make sure Sirius Black was trying to kill him. Hermoine and the guys have a falling out over two issues (Harry's broom and Crookshanks' presumed killing of Scabbers), which results in Hagrid giving Harry and Ron a talking to. Harry notices Crookshanks out and about, including with a Grim. And Lupin teaches Harry the Patronus Charm to fight off dementors, both real and fake.