Well, it could make for some really interesting dynamics. For example, Oliver might be more protective of Hermione, and Hermione could have an easier time getting involved with Quidditch related things since her brother is so into it. It could also change how the Gryffindor team views Hermione, seeing her as more of an insider since she's related to their captain.
One common theme is the exploration of their different personalities coming together. Hermione's studious and logical nature with Oliver's more athletic and competitive side often creates an interesting dynamic.
If Hermione was Oliver's sister in fanfiction, they could have all sorts of adventures. For one, they could team up to investigate strange happenings around Hogwarts that seem to be affecting the Quidditch games. Since Hermione is smart and Oliver is observant in the Quidditch field, they'd make a great team. They might also go on a quest to retrieve a lost Quidditch trophy that has some sort of magical power. And perhaps they'd get involved in a mystery involving a cursed Quidditch broom that is causing trouble for the players. Their combined skills would surely help them solve these problems.
Oliver Wood in fanfiction might interact with Hermione's family by being very respectful of their Muggle ways. He could ask a lot of questions about their lives, showing his genuine interest. At the same time, he would share his own experiences at Hogwarts, like his training sessions for Quidditch. He might also be a bit shy at first, but as the conversation goes on, he becomes more comfortable and starts to joke around a bit with Hermione's siblings if she has any.
In some fanfictions, it's possible for the author to create a fictional relationship where Hermione is Molly's sister. However, in the original 'Harry Potter' series, there is no such relation.
One possible fanfiction plot could be that with Hermione being Harry's sister, it adds a new layer of family drama to the relationship between Hermione and Draco. Maybe Draco has to face his own prejudices in a different way because she's not just a Muggle - born witch but also related to 'The Boy Who Lived'.
In some fanfiction, creative liberties are taken to create unexpected relationships. If Hermione is depicted as Lucifer's sister, it could be a very interesting take. It might be used to explore themes of good and evil in a new context, with Hermione's intelligence and moral compass clashing or interacting with Lucifer's more devilish nature. However, this is a far - fetched concept when considering the original Harry Potter and Lucifer - related canons which are from completely different fictional universes.
Well, if Hermione was Harry's sister, it would likely impact the way they approach challenges and adventures. They might have more shared family concerns and a deeper sense of loyalty. Also, their interactions with other characters could be different as their family status has changed.
The contrast between their personalities. Hermione is studious and intellectual, while Oliver is passionate about Quidditch. When they come together and share a kiss, it's like two different worlds colliding in a very exciting way.
You can find 'Oliver and Hermione' fanfiction on Fanfiction.net. It has a large collection of stories related to various fandoms, including Harry Potter where these two characters are from. Just use the search bar and type in 'Oliver and Hermione' to see a list of available fanfictions.