Swinging across burnt bridges
After the complete catastrophe that was fourth year - you know, triwizard tournament, death of a friend, the general fickle loyalties of the wizarding world - it's safe to say that Harry is nowhere close to being okay. Trapped and alone in a house that had never been his home, our favorite boy hero simply cannot resist opening the package his godfather gave him.
What follows is a series of events including, but not limited to: the revelation of a long lasting crush, several parties, therapy, and one strangely happy goblin - not exactly in that order.
Whatever the matter, Hogwarts, and the rest of the wizarding world, could never have prepared itself for a Harry Potter who embraced every facet of his personality - including the Slytherin bit.