A great fanfiction idea could be that the squinting Death Eater has a special power related to his squinting. For example, he can see hidden magical auras that others can't. This power could put him in a unique position within the Death Eater ranks. He might use this power to either further the Death Eaters' goals or, if he has a moral awakening, to undermine them.
Well, there's a fanfiction where a Death Eater has a change of heart after falling in love with a Muggle - born witch. This creates a whole new dynamic as they struggle between their loyalty to Voldemort and their new - found love. Then there are those that focus on the backstories of Death Eaters. For example, how they were recruited, what made them turn to the dark side in the first place. It gives a deeper understanding of their characters rather than just seeing them as pure evil minions. There's also a fanfic that imagines a world where Death Eaters take over Hogwarts and how the students resist them.
One interesting Death Eater Harry fanfiction could be 'The Dark Path of Harry'. In this fic, Harry is somehow drawn into the world of the Death Eaters, exploring a darker side of his character. It might show his internal struggle between the light he was brought up with and the allure of the dark magic associated with the Death Eaters.
There's a fanfic I've heard of called 'James Potter's Dark Path'. In this story, the author might take a different approach to James' character development. Maybe he was seduced by the power that the Death Eaters seemed to offer. It could also show how the other characters in the wizarding world react to this new, dark James Potter. They might initially not believe it or be in denial.
There might be a fanfiction where Harry's squint at Nagini occurs during a tense moment in a battle. He's squinting because he's trying to anticipate Nagini's next move, as she's a dangerous weapon in Voldemort's arsenal. This could lead to a series of events where Harry uses his knowledge of Nagini to gain an advantage in the fight against the Dark Lord.
One interesting fanfic could be 'The Redemption of a Death Eater'. It might explore a Death Eater's journey to break free from the dark side. Another could be 'Death Eater Alliances' which delves into the relationships and power plays among Death Eaters. There's also 'A Death Eater's Secret' that might reveal hidden motives or pasts of these dark wizards.
There's also 'The Lost Magic' in this genre. This fanfiction takes the idea of squinting hard at the existing magic in the Harry Potter world and expands it. It shows how there could be whole new areas of magic that the characters are just on the verge of discovering. It's really exciting as it combines the familiar elements of the series with new and innovative magical concepts.
There might be a fanfiction where Voldemort's death isn't as final as it seems in the original books. In this story, his followers find a way to bring him back in a more powerful and terrifying form, and Harry has to face this new threat with the help of his friends and some unexpected allies. Also, a fanfic could focus on Fred Weasley's death and how George struggles to cope, eventually finding a way to honor his brother by creating a new magical invention.
One interesting Sirius Black as a Death Eater fanfiction could be 'The Darkened Path of Sirius'. In this story, Sirius might be forced into the Death Eater ranks due to some dark family secrets. Another could be 'Sirius's Fall and Redemption'. It might explore how being a Death Eater changes him and his journey back to the good side. And 'The Alternative Sirius' could show a world where Sirius is a Death Eater from the start, changing the whole dynamic of the Harry Potter universe.
There might be a fanfiction where Harry Potter is at a Quidditch match without his glasses. He's squinting to try and spot the Snitch. This could lead to some interesting situations, like misidentifying other flying objects as the Snitch at first, and his team having to cover for him while he struggles without his proper vision.
There is a fanfiction where Death adopts Harry Potter and takes him on a journey through different magical realms. Along the way, Harry meets various magical creatures and beings that are not part of the normal Hogwarts curriculum. He gains knowledge about the true nature of magic and how it is intertwined with life and death. This knowledge helps him to become a more powerful and wiser wizard.