Well, one possibility could be that drunk Harry starts casting random spells all over Hogwarts. He might accidentally turn the Great Hall into a giant ice rink or make the portraits start singing opera. Another idea is that he thinks he's on a wild adventure and tries to 'fight' imaginary enemies, causing chaos in the corridors.
Neville could be in it too. He might be initially shocked to see Harry in such a state but then tries to help by using some of his herbology knowledge to make a potion to counteract the drunkenness. And Malfoy could show up, taking the opportunity to mock Harry until Harry, in his drunken craziness, does something that scares Malfoy off. Also, Hagrid would surely be around, being concerned about Harry and trying to get him to rest in his hut.
In some fanfictions like this, Harry Potter could go crazy because of a powerful dark magic curse. This curse might make him see his friends as enemies and vice versa. He could then start a series of chaotic events at Hogwarts, like trying to attack his best friends. Another idea is that Harry discovers a new type of magic that is so different from what he knows that it drives him to the brink of madness as he tries to understand and master it.
Obviously, Harry Potter himself would be the central character as the title implies. Hermione and Ron would most likely be involved as well, since they are Harry's closest friends. They would probably be the ones trying to figure out what's wrong with Harry and how to fix him. Dumbledore could also play a big role, as he often has the wisdom and power to deal with strange situations.
One interesting plotline could be that Harry's 'going crazy' is due to a powerful dark magic spell that was secretly cast on him. He starts seeing strange visions and having out - of - control magic surges.
Well, Harry could be really confused at first. Ouran is a very different world from Hogwarts. He might be shocked by the opulence of Ouran Academy and the strange club system there. Maybe he'd try to find a way to fit in while still being true to his wizard self.
Well, obviously Harry Potter himself is the central character. Hermione and Ron are almost always involved too. They would be the ones trying to figure out what's wrong with Harry and how to fix him. Dumbledore might also play a major role, as he often has deep knowledge about magic and could potentially help Harry regain his sanity.
One common theme is chaos. When the characters are drunk, spells go awry, and there are often comical situations. For instance, a drunk wizard might accidentally turn his friend into a strange animal. Another theme is self - discovery. The characters might act differently when drunk and learn something new about themselves. For example, a shy character could become more confident.
He might meet international aurors. These are highly skilled wizards from different countries who are experts in dark wizard catching. They could teach Harry some new combat spells.