One way Hermione could switch sides in fanfiction is through a major misunderstanding. For example, if the wizarding world turned against her for some false accusation, she might feel betrayed and be pushed towards the 'dark side'. Maybe she discovers that the so - called 'good guys' have been hiding some dark secrets that go against her moral code.
It could also be due to a strong emotional connection. Suppose she falls in love with someone on the 'opposing side'. Love has the power to make people change their loyalties. In this case, she might start to see things from their perspective and gradually switch sides as she tries to reconcile her newfound feelings with her old beliefs.
In a 'Draco switches sides' fanfiction, it might start with Draco being disillusioned with his family's long - standing loyalty to Voldemort. His experiences at Hogwarts, especially his interactions with some of the more morally upright students like Hermione or Harry, could gradually nudge him towards the other side. He might first resist the idea but then, after a major event, such as seeing an innocent person being brutally attacked by Death Eaters, he decides to switch sides and use his position within the Death Eaters to undermine them from within.
Harry Potter would surely be one of the key characters. His relationship with Draco, which has always been a mix of rivalry and grudging respect, could play a huge role. As Draco switches sides, Harry would be initially suspicious but then come to accept and work with him. Hermione Granger is also likely to be important. Her intelligence and strong moral compass could influence Draco further and she could be the one to first recognize his change of heart.
Well, one possibility is that Naruto, in Sakura's body, might struggle with her medical ninjutsu skills at first. Since he's used to more combat - oriented jutsu. He could accidentally mix up some of the medical herbs or misdiagnose a patient in the hospital. Meanwhile, Sakura in Naruto's body would likely be eager to show off his strength, but might find it a bit harder to control the Nine - Tails' chakra than she expected.
Obviously, Harry Potter himself is the central character as the title implies. Voldemort is also often involved as the main figure on the 'dark side' that Harry might switch to or interact with differently. Then there's Snape. His complex relationship with Harry could be a key factor in the story. In some fanfictions, he might be the one who either tempts Harry to switch sides or tries to prevent it depending on his own motives.
One interesting scenario could be Harry realizing that the so - called 'dark side' has been misrepresented. Maybe he discovers that the Death Eaters have some valid grievances against the Ministry's corruption, which makes him question his allegiance. Another could be that he's influenced by a powerful dark magic artifact that makes him see things from Voldemort's perspective, at least temporarily.
Another plotline could involve Harry being betrayed by the Order of the Phoenix. Feeling hurt and lost, he decides to side with Voldemort out of revenge. However, as he gets closer to the dark side, he realizes that Voldemort's true nature is far more evil than he thought and has a change of heart.
Obviously, Harry Potter himself is the central character as the story revolves around his switching sides. Hermione and Ron also play significant roles. When Harry starts to show signs of siding with the dark side, Hermione might try to use her intelligence to figure out what's wrong and bring him back. Ron, on the other hand, could be more impulsive in his reactions, either trying to fight Harry if he becomes a threat or trying to persuade him to return to the good side.
Well, it could be that a dark wizard uses a powerful charm on her to make her believe she's in love with someone and agrees to marry. Maybe he manipulates her memories so she doesn't remember who she really is or who she truly loves.
It could be that in the fanfiction world, Hermione was the victim of a spell gone wrong. This spell could have made her pregnant and also somehow cut her off from her usual support system, leaving her alone. Or perhaps she made a choice to distance herself from others because she didn't want to endanger them while she was dealing with this unexpected pregnancy.
In these fanfictions, Hermione's character often develops a more nuanced view of the wizarding world. She no longer sees things in the simple black - and - white way of Gryffindor vs Slytherin. She realizes that Slytherin has its own merits. So she becomes more open - minded and less judgmental. She also might develop a more complex social network, befriending Slytherins who have different outlooks from her old Gryffindor friends.