Harry gained a father figure

After learning Sirius Black was his godfather in Prisoner of Azkaban, for the first time ever Harry had a confidant akin to a parent. Unfortunately, Sirius was still at large for the murders he didn’t commit, so the pair resorted to sneaky letters, codenames and occasional and quite literal fireside chats, with Sirius using Floo Powder to pop his head in the Gryffindor common room fireplace.

As the events of Goblet of Fire proved extra stressful, Harry sought Sirius’s advice a lot, which was heartening to see. Especially considering the closest thing Harry had to a fatherly chat with Vernon Dursley was… well, there was nothing even close, really.