One possible plot could be that Harry is manipulated by a powerful dark force. Maybe Voldemort manages to find a way to break Harry's spirit through a series of cruel and deceptive events. For example, Voldemort could use false visions to make Harry believe that the Order of the Phoenix has betrayed him. Then, Harry, feeling lost and angry, starts to be drawn to the Death Eaters' ideology which offers him a sense of power and belonging that he thinks he has lost on the 'good' side.
The plot could develop in a very dark way. Harry might start hunting down the Order of the Phoenix members. He would be using his knowledge of the good side to help the Death Eaters. For example, he could lead them to the secret passages in Hogwarts.
In this fanfiction, Harry might become death in a symbolic sense. He could be the one who decides the fates of others, like a sort of Grim Reaper figure in the wizarding world. He might gain the power to see the life threads of people and has to make difficult choices about whether to cut them or not. This would put him in a very complex moral situation, as he has always been a hero who tries to save lives, but now he has this power that is closely related to ending lives.
In such a fanfiction scenario, it would completely颠覆 the original story. Harry would be on the side of evil, which means he might be involved in dark magic practices and attacking those he once considered friends and allies. It would be a very dark and扭曲的 version of the Harry Potter universe.
Another idea could be that she is somehow brainwashed. There could be a dark spell or a powerful magical object that alters her perception and makes her believe in the Death Eater ideology. In this scenario, her friends would have to find a way to break the spell and bring her back to her true self.
One possibility in this fanfiction could be that Hermione is forced to become a Death Eater due to a powerful dark magic spell that controls her mind. This would lead to a great internal struggle as her original values clash with the cruel and dark ways of the Death Eaters.
It could be about Hermione facing challenges from a Death Eater while dealing with the slur of being called 'mudblood'. Maybe the Death Eater tries to capture her for some dark purpose, and Hermione has to use her intelligence and magic skills to outwit the enemy.
It could be about Hermione somehow influencing a Death Eater to change their ways. Maybe she uses her intelligence and magical skills to show the Death Eater the error of their beliefs. For example, she might expose the true nature of Voldemort's regime which is based on fear and oppression, making the Death Eater question their loyalty.
The wizarding world would be in chaos. Harry has been seen as the 'Chosen One' to defeat Voldemort. If he becomes a Death Eater, the hope that the wizarding world has placed in him would be shattered. People would lose faith in Dumbledore's judgment for believing in Harry all this time. The Order of the Phoenix would be severely demoralized as they have been fighting for Harry's cause.
One consequence could be a distortion of the characters' original identities. Harry is a symbol of good, and a Death Eater is a symbol of evil. This pairing would muddle the clear - cut moral lines in the original story. Another consequence might be that it offends fans who love the original series for its values. It could also give a wrong impression to new readers or fans of the fanfiction, leading them to misunderstand the essence of the Harry Potter universe.
One common plot point is Harry's initial indoctrination into the Death Eaters. This might involve him being influenced by a powerful Dark wizard or some dark magic. Another is his struggle with his former friends, like Hermione and Ron, who now see him as an enemy. There could also be a plot about him trying to rise in the ranks of the Death Eaters while secretly having doubts about his new path.