I'm not really sure if there are popular ones specifically. Fanfiction can cover a vast range of really odd and unique concepts, but the idea of male Death Eaters in diapers is rather strange and not a common mainstream fanfiction theme. It might exist in some very niche corners of the fanfiction world, but it's not something I've come across frequently.
Some writers might use it as a way to explore the characters in a non - traditional way. The Death Eaters are often seen as one - dimensional villains in the original series. By creating this strange scenario of them in diapers, it allows the writer to delve deeper into their personalities in a more unconventional and humorous manner. It could also be a reaction to the often - overly - serious nature of fanfiction related to the 'Harry Potter' series, a way to add a bit of light - heartedness and absurdity to the mix.
Voldemort himself, of course, is the most prominent in a sense. But in the fanfiction, his relationship with the other Death Eaters could be different. He might be more distrustful or have different expectations of them. And then there's Barty Crouch Jr. He could be a major player in the fanfiction, with his skills in disguise and dark magic. His actions could drive some of the major plotlines in the fanfiction.
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.
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, 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.
One great fanfiction with Hermione and multiple Death Eaters could be 'The Dark Encounters'. In this story, Hermione finds herself in a situation where she has to outwit several Death Eaters at once. It shows her intelligence and bravery in the face of danger. Another one might be 'Hermione's Trials Among the Death Eaters' which delves into how she uses her magic skills in a unique way to deal with them.
Perhaps there is a prophecy that the Death Eaters misinterpret at first. They think killing Harry is the right thing, but later they discover that saving him is actually crucial for their own survival or for some greater good in the wizarding world. So they decide to go against Voldemort's orders and save Harry. For instance, they find out that Harry has some power that can prevent a much greater evil from emerging, which would also threaten the Death Eaters.
Another theme is power struggle. Hermione, with her knowledge and magic skills, often has to face the power - hungry Death Eaters. It creates a lot of tension in the stories.
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.