In the Hogwarts hierarchy, things would change. Hermione is often seen as a bit of an outcast by some Slytherins because she's a Gryffindor. Draco, now in her body, would face a different kind of discrimination or at least a lot of strange looks from his own housemates. He would also have to deal with Hermione's reputation among the teachers. Some teachers might expect the same level of knowledge and participation from 'Hermione' (who is actually Draco), and he would struggle to meet those expectations.
Another way could be through a potion gone wrong. In the wizarding world, potions can have all sorts of strange effects. If Draco was trying to brew a potion for some other purpose, like trying to gain an advantage in a competition or something, and made a mistake in the ingredients or the brewing process, it could result in him being transformed into Hermione. This would force him to experience life from her perspective, which could be a huge character - development opportunity for him.
One possible fanfiction scenario could be that Draco and Hermione are forced to work together on a school project in Hogwarts. At first, they are at odds due to their different houses and backgrounds. But as they dig deeper into the project, they start to see each other's intelligence and determination. Draco realizes that Hermione is not just a 'Mudblood' but a brilliant witch, and Hermione sees that Draco has more to him than just his Slytherin arrogance.
A possible fanfiction plot could be that Draco, now a girl, discovers new magical abilities that were suppressed in his male form. These powers could be related to a more intuitive connection with magic, something that is often associated with femininity in the wizarding world. This newfound power could put her in a position where she has to choose between using it for the benefit of Slytherin or for the greater good of Hogwarts, creating a moral dilemma for her character.
In some fanfictions, there could be a time - travel element. What if Draco and Hermione are sent back in time? They might have to work together to ensure the future they know doesn't change. This could lead to some interesting character development as they are forced to rely on each other in a completely different time period, and they may see each other in a new light as they face challenges together.
Well, first of all, a good understanding of the original characters is crucial. The fanfiction should stay true to their personalities. For example, Draco's pride and Hermione's intelligence should be intact. Also, an interesting plot that forces them to interact in new ways. Like, a mystery they have to solve together or a situation where they are on the same side against a common enemy.
One possible motive could be to gain an advantage over Harry Potter. Hermione is Harry's closest friend and a very intelligent witch. By kidnapping her, Draco might think he can use her as a bargaining chip to make Harry do something or to get information from her that could be useful to the Death Eaters. Another reason could be jealousy. Draco has always been in competition with the Gryffindors, and Hermione's intelligence and skills might make him envious to the point of doing something drastic like kidnapping.
His personality might become more empathetic. As a girl, Draco could start to see things from a different perspective. For example, he might be more sensitive to the way others are treated, especially other girls in Hogwarts.
In terms of his relationships with his Slytherin peers, some might look down on him. But others could be intrigued. Pansy Parkinson, for example, might see Draco as a girl as a threat to her status as the 'queen bee' in Slytherin. However, some of the more open - minded Slytherins could befriend Draco and help her deal with the challenges of being a girl in a very traditional and often misogynistic wizarding society.
One possible scenario could be that Draco has a change of heart at Malfoy Manor. He might secretly try to protect Hermione from the other Death Eaters. Maybe he uses his knowledge of the manor's secrets to hide her or mislead the others. For example, he could tell them she escaped through a certain passage when in fact he has her hidden in a secret room.