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.
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.
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.
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.
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.
Perhaps Harry discovers some long - hidden family secrets that make him believe that the so - called 'good side' has been wrong all along. He might find out that his family has a connection to the Dark Arts that was misrepresented by Dumbledore and others. This newfound knowledge could cause him to change sides and try to rewrite the wizarding world's view of good and evil.
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.
Another plot could involve Harry being influenced by a family connection he discovers to a Death Eater. This newfound relation makes him reevaluate his beliefs and he starts to see the Death Eaters as more than just pure evil. He might think that by joining them, he can reform them from the inside.
Well, some might involve magical creatures with furry characteristics in new adventures at Hogwarts. For example, a werewolf character could have a unique story arc that intersects with the main Harry Potter plot. Maybe they are trying to find a cure or dealing with the prejudice within the wizarding world in a different way than what's in the original books.
One possible plotline could be a comical take on baby Harry's magical mishaps. Maybe he accidentally makes his diapers levitate or turns his crib into a mini Hogwarts. Another could be about how the other characters like Hagrid or Dumbledore interact with baby Harry in this unique situation, perhaps trying to figure out how to handle his early magical outbursts while he's still in diapers.
Perhaps a plotline where the ogre has some sort of special power that the wizards in Harry Potter are interested in. This could lead to a whole series of events where they try to either control or cooperate with the ogre.