Love and manipulation could also be a common theme. In these fanfictions, the relationship between female Harry and Voldemort is likely to be a complex mix of love (or something like it) and manipulation. Voldemort is a master manipulator, and seeing how he uses his skills on the female Harry, and how she either succumbs to or resists it, is a theme that can add a lot of depth to the story. Also, the idea of redemption or the lack thereof for both characters can be an important aspect in these types of fanfictions.
One common theme could be power dynamics. With Harry being female and in the role of Voldemort's queen, there would be a complex play of power between them. Voldemort is a very powerful and dark wizard, and how the female Harry navigates this relationship in terms of power is often explored.
One common theme is identity struggle. Fem Harry has to grapple with being the daughter of the most feared dark wizard while also having her own sense of self. Another theme is redemption. There's often an attempt to show that, despite her heritage, she can choose the path of good. And of course, there's the theme of family. It explores what family means when your father is Voldemort, and how that affects her relationships with other characters like the Weasleys who represent a more traditional, loving family.
Well, finding such a specific type of fanfiction might take some time. You can also look into Tumblr. There are a lot of Harry Potter fans on Tumblr who share and discuss fanfictions. They might have some posts about 'fem Harry is Voldemort's queen' fanfictions or know where to find them. Just be aware that not all content on Tumblr is organized in the most straightforward way, so you may need to dig a bit.
Common themes in such fanfictions include identity crisis. Hermione is no longer the same person she was, and she has to reevaluate her identity as Voldemort's queen. Another theme is the clash of ideals. Her own beliefs about good and evil are in direct conflict with Voldemort's. This can lead to some intense internal and external conflicts within the story. Additionally, the theme of sacrifice might come up. She might have to sacrifice some of her own principles or relationships in order to survive in this new role or to achieve a greater good in the long run.
The theme of forbidden love also often appears. Given their status as enemies in the original story, the idea of them having some sort of romantic or deep emotional connection in fanfiction is a popular one. It adds an element of drama and tension to the story.
The theme of trust is often present. Given that Harry and Voldemort are usually enemies, when it's a female Voldemort, the story might focus on how they learn to trust each other or not. And the theme of changing fate. They might try to change the fate that would usually lead to their enmity, for example by working together to prevent a greater evil.
One common theme is the struggle for identity. When Harry is Voldemort's possession, he often has to fight to retain his sense of self. Another theme is power imbalance. Voldemort is extremely powerful, and Harry's new position as his possession creates a huge power gap that the story often explores.
One common theme could be power dynamics. With Voldemort as Harry's master, there would be a complex play of power, dominance, and submission. Another theme might be redemption. Maybe the story could explore if Harry can somehow redeem Voldemort or if Voldemort can find a different path despite being in a position of power over Harry. Also, identity confusion could be a theme, as Harry has to deal with being under the control of his archenemy in a new and unexpected form.
One common theme is identity struggle. Harry would be in a turmoil trying to figure out who he is in relation to Voldemort. Another is the reaction of the wizarding world. How would they accept or reject Harry given his new family connection.
Love and hate are also common. The complex relationship between fem Harry and Voldemort can be filled with both love and hate. It could be a romantic kind of love or a more platonic love - hate relationship. Identity is another theme. Fem Harry may have a different identity in the wizarding world compared to male Harry, and this affects how she deals with Voldemort.
The theme of redemption can also be found. There are stories where Voldemort might be on the path to some form of redemption through his interactions with fem Harry. Also, the idea of forbidden love or a strange attraction sometimes pops up. It's a very different take on the original relationship between Harry and Voldemort. It challenges the traditional view of good and evil. And in some fanfictions, there's the theme of sacrifice. Fem Harry might have to sacrifice something dear to her in order to defeat Voldemort or change his ways.