In a fanfiction where Hermione is captured by Death Eaters, it could be a very dark and tense plot. The Death Eaters might torture her to get information about Dumbledore's Army or the whereabouts of Harry Potter. Hermione, being strong - willed, would resist as much as she could. Her friends would be desperate to find her, and there could be a lot of internal struggles within the wizarding community about whether to negotiate with the Death Eaters for her release or fight back directly.
Well, in this kind of fanfiction, perhaps Hermione is captured because she was on a solo mission to retrieve some important magical item. The Death Eaters could use her knowledge to try and break into the secrets of the Order of Phoenix. Meanwhile, Hermione could be using her wits to delay them and send out hidden signals for help.
In this fanfiction, Hermione could rehabilitate Death Eaters by showing them the error of their ways. She may expose them to the harm they've caused to both the Muggle - born and the wizarding community at large. By making them face the consequences of their actions on a personal level, like the families they've torn apart, she might start to change their views.
The story could develop with Hermione trying to escape on her own. She might use her intelligence to find weaknesses in the Death Eater's security. For example, she could figure out the patterns of their patrols and use her magic to create distractions.
Well, she could end up in a duel with a powerful Death Eater. Hermione is a very skilled witch, so it would be a great show of her magical abilities. Maybe she discovers a new spell during the fight that helps her gain the upper hand.
One way it could develop is through the use of dark magic coercion. Maybe a powerful Death Eater discovers Hermione's intelligence and decides to use Imperius Curse to make her his slave. He could force her to use her magic skills for his evil purposes, like brewing dangerous potions or stealing valuable magical artifacts.
Perhaps in the fanfiction, Hermione has something that the Death Eaters are after, like a powerful magical artifact. They fight over who gets to take her prisoner first in order to extract the location of this artifact from her. It could also be that they are under the orders of Voldemort to capture her alive, but they start fighting among themselves due to personal rivalries and the desire for glory within the Death Eater ranks.
Hermione could resist the Death Eaters with her vast knowledge of magic. For example, she could use protective spells and charms she has learned from her studies. She might also use her quick thinking to outwit them in verbal exchanges, not giving them any information or advantage.
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 Hermione discovers that one of the Death Eaters training her has a change of heart. This Death Eater then starts to help Hermione escape or undermine the other Death Eaters from within the group. It adds an interesting layer of complexity to the story.
One possible motivation could be that she's been tricked. Maybe a powerful Death Eater has cast a spell on her to make her believe their cause is just. Another could be that she's trying to protect her friends. She might think that by joining the Death Eaters, she can keep Harry and Ron out of danger.