A possible plotline could be that a Death Eater discovers Hermione has knowledge of a powerful spell or magic item that could help them overthrow Voldemort. So, they save her to get that information. For example, she might know of a way to break a powerful curse that Voldemort has placed on them.
One possible plotline could be a story of redemption. Maybe a Death Eater starts to question their beliefs after getting to know Hermione on a deeper level. For example, they could be forced to work together on a mission and gradually see the good in her, leading to a change in their ways.
A possible motive could be self - preservation. If they believe that Voldemort's downfall is inevitable and that by saving Harry, they can gain some form of leniency from the side that opposes Voldemort. They might think that Harry has enough influence to spare their lives if they help him.
Well, it could start with Hermione being kidnapped by the Death Eaters at a young age. She might be forced to attend their dark magic lessons. However, she uses her intelligence to learn about their weaknesses. For instance, she could discover a flaw in the security spells around their lair. And then, as she grows up, she could start to subtly manipulate the Death Eaters into fighting among themselves, all while pretending to be a loyal follower.
She could face legal issues in the wizarding world. Killing is not taken lightly, even if it's Death Eaters she's killing. There might be a trial to determine if her actions were justified. If the wizarding authorities are corrupt or influenced by the wrong people, she could even be wrongly convicted.
A plotline could involve Hermione being in a situation where she has to negotiate with two Death Eaters. Through the negotiations, they start to see her intelligence and strength. They form an unlikely bond where they end up protecting each other from other threats in the wizarding world. This bond could be written in a way that explores the idea of a threesome in terms of their connection and how they function together as a unit, without any sexual connotations. It could be about breaking down the barriers between the 'good' and the 'evil' in the context of the Harry Potter universe.
A fanfiction involving Hermione and Death Eaters could focus on a moral dilemma. For example, if Hermione has the chance to save a Death Eater's life, would she do it? This could explore her character's sense of right and wrong. It could also be about how she endures the psychological torture that the Death Eaters might inflict on her, showing her strength and resilience.
Well, in some fanfictions, Hermione might use her superior intellect. She could outwit the Death Eaters by setting up elaborate magical traps. For example, she could use transfiguration magic to create objects that suddenly turn into something dangerous when the Death Eaters approach. Another way could be through her extensive knowledge of potions. She might create a potion that incapacitates or kills them when they come into contact with it.
Maybe the Death Eaters save Harry, but then they try to use him as a bargaining chip. They think they can trade Harry's safety for something they want, like amnesty or a powerful magical artifact. However, things don't go as planned and they end up having to truly protect him.
One consequence could be that she is forced to perform dark magic against her will. This would be a huge moral struggle for her, as Hermione is a firm believer in the light side of magic. It could also change her perception of herself and her magic abilities in a very negative way.
One possible reason could be Hermione's intelligence. In the Harry Potter series, she is extremely smart, and the Death Eaters might be intrigued by someone with such powerful intellect in a fanfiction scenario. They could see her as a valuable asset or a challenging target.