Power and its proper use is also a common theme. Slytherin was known for valuing power. The descendants in fanfictions often have to figure out how to use their power in a positive way. Some might have unique magical abilities passed down from Slytherin, and they need to decide whether to use them for self - gain or for the greater good of the wizarding community.
One common theme is redemption. Since Slytherin has a somewhat dark reputation, the descendants often have to prove that they are not evil. For example, they might fight against dark wizards to show that they are on the side of good. Another theme is identity. Discovering they are a Slytherin descendant makes them question who they are and how they should act.
One common theme is the struggle against prejudice. Since Slytherin has a reputation for being the 'evil' house, Harry often has to fight against the preconceived notions of others. For example, in many fanfictions, the Gryffindors are initially suspicious of Harry being in Slytherin.
One common theme is the exploration of a different Hogwarts experience for Harry. Since Slytherin has a different reputation than Gryffindor, Harry might face different challenges and prejudices. Another theme could be the discovery of a hidden Slytherin heritage, which might involve uncovering long - lost family secrets.
One common theme is identity. The fem Harry has to grapple with being the heir of Slytherin while also being the 'Chosen One' in a way. Another theme is prejudice. The wizarding world may be more suspicious of a female Slytherin heir compared to if it were male. And then there's the theme of power. She has to learn to control and use the power associated with Slytherin's heritage.
A common theme is the discovery of hidden Slytherin powers. Harry often has to learn to control and use these powers in unique ways.
A lot of these fanfictions explore the concept of family. How does her being in Slytherin affect her relationship with Harry and other family members? Also, the theme of acceptance. The sister has to deal with the fact that Slytherin has a bad reputation in the wizarding world, and she has to find acceptance within that house and from others. For example, in some fanfics, she has to prove that she's not like the 'evil' Slytherins people expect.
One common theme is identity. Since the female Harry is the Slytherin heir, she has to figure out who she really is in relation to this new identity. Another theme is acceptance. She often has to gain acceptance from both the Slytherin house, which may be skeptical of her at first, and from the other houses that might be distrustful of Slytherin. Power is also a theme. As the heir, she may have special powers or a connection to ancient magic, and the fanfictions often explore how she uses or is tempted by this power.
One common theme is the struggle for acceptance. Harry, being in Slytherin where he is abused, has to fight to be accepted not only by his housemates but also by others in Hogwarts. For example, in many such fanfictions, he has to prove that just because he's in Slytherin doesn't mean he's like the abusers.
One common theme is the idea of isolation. Since Harry is cold and in Slytherin, he often isolates himself from others, whether it's his old Gryffindor friends or new Slytherin acquaintances. Another theme is redemption. His coldness might be seen as a negative trait at first, but as the story progresses, he might start to show more warmth and redeem himself in the eyes of others.
Friendship and loyalty are also big themes. A female Harry in Slytherin has to find true friends within the house. Sometimes, she might have to break through the barriers of Slytherin's traditional cliques to find those who will be loyal to her, and in turn, she has to show her loyalty in unique ways, different from how the male Harry showed loyalty in Gryffindor.
One common theme is identity crisis. Harry has always identified as a Gryffindor, so finding out he's Slytherin's heir makes him question who he really is. Another theme is prejudice. People in the wizarding world often have negative views of Slytherin, so Harry has to deal with that when his heritage is revealed.