In this fanfiction concept, the storylines would be drastically altered. Hermione's character arc could be completely different. She might not be as close to Harry and Ron if she was part of the Malfoy family. There could be family secrets and politics involved. For example, the Malfoy family might try to use Hermione's intelligence for their own gain in the wizarding world. Draco would also have a new responsibility towards Hermione. He might be more protective or even try to manipulate her into following the Slytherin way. And the Hogwarts sorting hat might have a really hard time deciding where to place Hermione, given her family ties to Slytherin but her own Gryffindor - like qualities.
Well, if Hermione was Draco's little sister in fanfiction, it would completely turn the story on its head. For one, the Gryffindor - Slytherin dynamic would be super messed up. Hermione, being a know - it - all Gryffindor, and Draco, the snobbish Slytherin, their relationship would be full of internal conflict. Instead of being enemies, they'd have a family connection. This could lead to some really interesting scenarios where Hermione might be torn between her Gryffindor friends and her Slytherin family. Also, Draco might have to protect Hermione from the more evil Slytherins like Bellatrix, which would be a strange role - reversal. And it could change the way the whole wizarding world views blood purity because Hermione, as a Muggle - born, being related to a pure - blood Malfoy would shatter some long - held beliefs.
It would change a great deal. Firstly, Hermione's upbringing might be different. Maybe she would have been raised in a more privileged environment rather than as a Muggle - born in a non - magical family. This could affect her personality. She might be less of an over - achiever as she wouldn't have to prove herself as much. Draco, on the other hand, would have to deal with having a sister who is friends with his enemies. It could also change the way the war is fought. Hermione might be able to use her connection to the Malfoy family to broker some sort of peace or at least gain some inside information. In the end, it would create a whole new set of relationships and power dynamics within the wizarding world.