There's a fanfic titled 'Harry in Slytherin: Overcoming Abuse'. In it, Harry's sorting into Slytherin is a shock to many. But within Slytherin, he finds a sense of belonging. The house's values of ambition and self - preservation help him deal with his abuse. The story shows how he transforms his pain into strength with the support of his Slytherin peers. It's a story of redemption and growth.
It makes him more cynical. Harry, after experiencing abuse, is less trusting when sorted into Slytherin. He uses the house's cunning to protect himself from further harm.
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.
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 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.
Well, in Slytherin, Harry could end up being one of Snape's top students. This might lead to a more positive relationship. Snape might see Harry as a chance to redeem the Slytherin image. He could start to trust Harry more and share some of his knowledge about dark magic in a more open way, which was not possible when Harry was in Gryffindor.
His character would become more complex. He'd have to balance his own values with the Slytherin ideals. Harry would likely become more politically astute as he'd have to navigate the power plays within the Slytherin house.
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.
Draco Malfoy would be a likely character. Since they are in the same house now, they would have more opportunities to interact. Their relationship could start off as hostile as always, but then gradually change as Hermione shows different aspects of herself in Slytherin.