I really liked 'Harry in Slytherin: A New Path'. It explores how Harry's values and actions might be different if he were in Slytherin. He has to deal with the Slytherin house's reputation and the prejudices that come with it. The author does a great job of showing how he might use his intelligence and cunning in a more Slytherin - like way.
One common theme is identity crisis. Harry has always been seen as a Gryffindor, so when he's sorted into Slytherin, he struggles with who he really is. Another theme is friendship. He has to form new friendships with Slytherins who have different values from his Gryffindor friends. For example, he might have to learn to trust Slytherins who are known for their cunning.
Another plot could involve Harry discovering some long - lost Slytherin secrets. Maybe there are hidden chambers or spells that only Slytherin students are supposed to know about. Harry, being the curious and brave character he is, delves into these secrets. This could put him in a dangerous position as some Slytherins might not want him to expose or use these secrets, but it also gives him a chance to prove himself to his new housemates.
At first, Harry might be confused and a bit out of place. He's used to the Gryffindor way of thinking. But in Slytherin, he has to adapt. He becomes more cunning in a positive sense. He learns to think on his feet and use his wits in different ways than he did in Gryffindor. For example, instead of charging into a situation like he might have in Gryffindor, he starts to plan more carefully.
One great fanfic could be 'The Slytherin's Albus'. It shows Albus's journey in Slytherin, his struggles with the house's reputation and how he forms unique friendships. It's really interesting as it gives a new perspective on Albus compared to the original stories.
Well, he might face a lot of challenges. In Slytherin, he'd be surrounded by students with different values compared to Gryffindor. He could have a tough time making true friends at first. But it might also give him a chance to change the perception of Slytherin from within. He could use his Gryffindor courage to influence the more cunning and ambitious Slytherins towards a more positive path.
One interesting fanfiction could be 'The Slytherin Prince Harry'. In this story, Harry's sorting into Slytherin changes his whole Hogwarts experience. He has to deal with the prejudice from the Gryffindors while also trying to find his place among the Slytherins. It shows a different side of Harry, more cunning and politically aware.
One great fanfiction in this vein is 'The Slytherin Heir' where Harry, having endured abuse, is sorted into Slytherin. It delves into his complex relationships with his housemates and how he overcomes the stigma associated with Slytherin. The story shows his growth and development as he uses his Slytherin cunning to face the challenges in the wizarding world.
One common theme is redemption. Harry, having been abused, often finds a way to redeem himself or be redeemed in the eyes of others through his actions in Slytherin. Another theme is identity. He has to grapple with his new identity as a Slytherin, which is different from the typical Gryffindor image of him.
One idea could be Harry having to deal with the prejudice from his Gryffindor friends. For example, Ron might be initially very suspicious and distant, which forces Harry to prove that he's still the same person. Another plot could involve Harry using Slytherin's more cunning and ambitious traits to fight Voldemort in a different way than in the original story. He might form alliances within Slytherin that were previously unthinkable.