One interesting plot twist could be that Harry uses his Slytherin cunning to reform the house's negative image. He might convince his housemates to abandon pure - blood supremacist ideas and focus on academic and magical achievements instead.
Well, one interesting plot could be that Harry, being in Slytherin, uses his natural leadership skills in a different way. He might form unexpected alliances within the house, like with the more cunning and ambitious students who are not as extreme as the pure - blood supremacists. This could lead to a new kind of Hogwarts politics where Slytherin is not just seen as the 'evil' house.
Perhaps a major plot twist is that the 'Prince of Slytherin' has a secret connection to Harry Potter. For example, they could be long - lost relatives. This would completely change the dynamic between Harry and the Slytherin character and lead to unexpected alliances and conflicts in the fanfic.
One interesting plot twist could be that Harry, in joining Slytherin, discovers a long - hidden family connection to one of the prominent Slytherin families. This changes his perception of his own identity and makes him question his place in the wizarding world.
In some fanfictions, a great plot twist is that the 'Prince of Slytherin' is not who everyone thinks he is. He might be under a powerful charm or disguise. And when the real identity is revealed, it turns out to be someone who has been working undercover for Dumbledore all along, which shocks both the characters in the story and the readers.
One interesting plot twist could be that Harry, being in Slytherin, forms an unexpected alliance with Draco Malfoy. Instead of the typical rivalry, they team up to uncover a dark secret within the Slytherin house that threatens the whole school. This changes the dynamic of the story as they have to work together despite their differences.
One plot twist could be that there's a prophecy about a Slytherin and a Gryffindor uniting the wizarding world, which is revealed to be about Harry and Ginny. This forces them to deal with a lot of attention and expectations from the wizarding community. It also makes their relationship a focal point of a much bigger plot, with dark forces trying to stop them from fulfilling the prophecy.
One possible plot twist could be that they go into Slytherin and are initially shunned by the other Slytherins. But then they discover a hidden group within Slytherin that has different values from the traditional Slytherin ones. This group is more inclusive and values knowledge and friendship over pure - blood supremacy. Harry and Hermione then work with this group to change the perception of Slytherin within Hogwarts.
Harry develops a different sense of loyalty. In a Slytherin environment, loyalty is often more conditional. So he learns to balance his own values with the more self - serving loyalty that exists in Slytherin. He may still hold onto his core beliefs of right and wrong, but he also understands the need to look out for himself and his housemates in a more Slytherin way. This could mean being more selective about who he trusts and how he shows his trust. He also becomes more aware of the power dynamics within the house and the wizarding world in general. He has to use his new - found Slytherin skills to survive and thrive, which changes his character in a more calculating and politically - aware way.
One great fanfiction could be 'Time's Twist in Slytherin'. In this story, Harry's time travel leads him to be sorted into Slytherin. He has to navigate the complex politics and relationships within the house. It shows a different side of the Slytherin characters and how Harry's presence changes things. He forms unexpected alliances and discovers secrets that were long buried.
One interesting plot twist could be that Hermione, as a Gryffindor in the original series, starts to question the values of her own house because of her newfound admiration for Slytherin. Maybe she discovers a long - lost family connection to a Slytherin family, which makes her more empathetic towards their ways. Another could be that she uses Slytherin - like cunning to solve a problem that Gryffindor bravado couldn't handle, causing a rift between her and some of her Gryffindor friends.