One common theme could be the exploration of Hermione's French heritage. It might involve her having a different family background in France, with perhaps Pureblood relatives who have their own set of traditions and values. Another theme could be her interaction with the French wizarding community. Maybe she attends a French wizarding school for a while and has to adapt to different teaching styles and social norms there.
Often, there are plotlines where Hermione as a pureblood princess has special powers or abilities that come with her status. For example, she might have an innate magical ability that is unique to pureblood princesses in the fanfiction world. This could then be used to save the day in various situations, like fighting against dark wizards or solving complex magical mysteries.
One common theme is the clash of cultures. Hermione, being Muggle - born, has her own set of values and beliefs which often conflict with the pureblood traditions. Another theme is her growth as a character. As she learns about pureblood ways, she becomes more understanding and adaptable. Also, the exploration of forgotten or hidden pureblood magic is a theme. For example, she might discover ancient spells or rituals.
Redemption is also a theme. There are fanfictions where Bellatrix has a chance at redemption through her relationship with Hermione. Maybe Hermione sees something in Bellatrix that others don't and tries to bring out the good in her. It's an interesting way to explore the character of Bellatrix beyond her villainous role in the original books.
Often, these fanfictions might also focus on the flaws of Ron that are exaggerated. This is done to contrast with Hermione's pureblood - associated positive traits. It could be about Ron's insecurities being blown out of proportion, like his jealousy issues, which are then used to make Hermione look better in comparison. And sometimes, it might be about exploring how Hermione's pureblood status could have changed the power dynamics in her relationships throughout the story.
In these fanfics, a common theme is the re - writing of Hermione's social standing. Since she's now a pureblood, she might be thrust into a different social circle. This could lead to themes of social climbing or resistance to it. Another theme could be the exploration of the pureblood culture. How does Hermione adapt to the traditions, values, and expectations of the pureblood society? And of course, there's always the theme of self - discovery. As she learns about her new identity as a pureblood, she also discovers new aspects of herself, her magic, and her place in the wizarding world. It can be really fascinating to see how different authors handle these themes in their fanfics.
Power and responsibility. Since Harry is a pureblood lord, he often has to deal with the power that comes with his new status and the responsibility to use it well. Another common theme is identity. He has to figure out how this new identity fits into his existing self.
A common theme is the clash of different magical worlds. Hermione comes from the world of Hogwarts and wizarding Britain, while the Mikaelsons are part of a very different supernatural world. Fanfictions might explore how Hermione adapts to this new world. There could also be a theme of love interests. Maybe Hermione falls for one of the Mikaelson siblings, which would be a big deal considering the Mikaelsons' dangerous and alluring nature. This could lead to a lot of drama and conflict as she tries to balance her feelings with the chaos that often surrounds the Mikaelsons.
One common theme is acceptance. Hermione often has to accept the werewolf side of the characters she encounters. Another is the struggle against prejudice, as werewolves are often discriminated against in the wizarding world.
A prevalent theme might be a love story. Hermione could fall in love with a mermaid or a merman. This would involve overcoming the differences between their two species, such as the fact that she is a witch and he/she is a mermaid. There would be cultural clashes as well as the physical limitations of their relationship, like how they can be together considering one lives on land and the other in water. Their love story could also be intertwined with a greater plot, like saving the mermaid population from a threat or something similar.
A common theme is the struggle with identity. Hermione, as a vampire, has to figure out who she is now. Another theme is the relationship with her friends. Since she's different, it might change how they interact. For example, they could be scared of her or try to help her.