In this type of fanfiction, Harry being in Slytherin can completely change the power dynamics at Hogwarts. His presence could split the Slytherin house into two factions: those who support the old - fashioned ways and those who are influenced by Harry's more inclusive views. This could lead to some intense rivalries and competitions within the house. Also, his new Slytherin friends might introduce him to different types of magic or spells that are more on the sly or cunning side, which would give him a whole new set of skills to use against the Dark forces.
One interesting plot could be Harry struggling to fit in with the Slytherin ideals at first. He might be constantly at odds with some of the more traditional Slytherin values like pure - blood supremacy. But then he could gradually change the house from within, making his Slytherin peers see that not all Gryffindor traits are bad and vice versa.
Well, in such fanfictions, Harry could form unexpected alliances. For example, he might team up with Draco Malfoy in a way that was never possible in the original books. Their combined skills and knowledge could lead them to uncover secrets about Hogwarts or the wizarding world that were previously unknown. And his time in Slytherin could also lead to a different kind of relationship with Snape. Maybe Snape would be more of a mentor to him than in the original story.
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.
One possible plot development could be that Harry has to face a lot more internal conflict. He would be associated with a house that his friends might view with suspicion. Also, he might discover new magical abilities or powers that are related to the Slytherin heritage.
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.
There are various plot ideas. Some fanfictions might explore the idea that the heir of Slytherin is not a single individual but a group of people who have been secretly working to change the reputation of Slytherin house. They could be working against dark wizards within the house who are trying to revive the old ways of pure - blood elitism. Or perhaps the heir has a connection to an ancient magic that is tied to Hogwarts itself, and in order to save the school from a new danger, they must unlock this magic. It could also be a story where the heir is in a love triangle with a Gryffindor and a Hufflepuff, adding a romantic element to the plot while still dealing with the challenges of being the heir of Slytherin.
Another development could be her relationship with the other houses changing. The Gryffindors might initially be suspicious of her new Slytherin status. However, Hermione could use this as an opportunity to bridge the gap between the two houses. She could show that just because she's in Slytherin doesn't mean she's abandoned her Gryffindor courage and loyalty.
In some of these fanfictions, Harry might gain god - like powers and use them to reshape the wizarding world. For example, he could end all forms of dark magic at once. Maybe he uses his newfound divinity to bring back lost loved ones, like his parents, in a way that doesn't disrupt the natural order too much.
In some of these fanfictions, Harry might start exploring the dark art of necromancy secretly. He could be driven by a desire to bring back his lost loved ones, like his parents. This often leads to him having to hide his newfound interest from his friends at Hogwarts, creating a lot of internal conflict as he struggles between what he knows is right and his longing for his family.
One interesting plot development can be that Harry levels up his Occlumency skills to an extraordinary level. This would mean he can not only block Voldemort from invading his mind but also be able to read the minds of others to some extent. This would give him a huge advantage in battles and in uncovering mysteries. For instance, he could use this skill to figure out the true intentions of some of the more ambiguous characters in the wizarding world, like Snape. And it would completely change the dynamics of his relationship with other characters, as they would be more cautious around him knowing he can peek into their thoughts.
In some fanfictions, Harry inheriting a fortune could lead to him having more political power in the wizarding world. He could use this to change laws that are unfair to certain magical creatures or groups. For example, he might fight for the rights of house - elves. He could also use his money to fund research on dark magic prevention, making the wizarding world a safer place.
One interesting plot development could be the exploration of Harry's relationship with Sirius Black outside of prison. Maybe they go on adventures together, hunting down remaining Death Eaters. Another could be Harry's improved skills in Defense Against the Dark Arts, as he now has Sirius as a more regular mentor. And perhaps there are new magical creatures introduced that Harry and his friends encounter during their post - Azkaban adventures.