Ron would probably be a character who is deeply conflicted. He might initially try to bring Harry back to the light but then be forced to choose between his friendship with Harry and his family's values. Snape, too, could have a very different role. Instead of hating Harry, he might see Harry's new - found power as a threat to his own secrets and motives in the wizarding world.
Hermione would be one. Instead of being Harry's loyal friend, she might be one of the first to oppose Harry's turn to the dark side. Or, in a more complex take, she could be torn between her loyalty to Harry and her belief in the right way of magic.
Dumbledore is a key character that would be portrayed differently. In an 'evil lord harry potter fanfiction', Dumbledore might be seen as more of a manipulator. Harry could view Dumbledore as someone who has been using him all along and this could be a major factor in his turn to the dark side. Also, characters like Draco Malfoy could either become Harry's ally in his dark plans or still be an enemy but for different reasons than in the original story.
Harry Potter himself is often portrayed differently. He might be more of a tough - guy, with a rougher edge to his personality. Instead of just being the hero against Voldemort, he could be dealing with gangster - like threats within the wizarding world. Hermione can be shown as a shrewd negotiator, using her intelligence to make deals with different gangs to protect her friends. Ron might be turned into a more street - wise character, perhaps having connections to some of the less - reputable parts of the wizarding community.
The relationship could be shown as a mentor - mentee type in some fanfictions. Maybe the Dark Lord, in an alternate reality, decides to teach Harry some of his dark magic knowledge not to corrupt him, but to make him stronger to face other threats in the wizarding world. This would completely change the dynamic between them. They could also be shown as reluctant allies, forced to work together to stop a greater evil that is emerging in the wizarding world. This would involve a lot of tension and distrust between them at first, but gradually they could start to understand each other more.
In some fanfiction, inquistors are shown as more corrupt than in the original books. They might take bribes or abuse their power for personal gain. For instance, an inquistor could let a known dark wizard go free in exchange for a valuable magical artifact.
Sasuke is often a popular character to be portrayed differently. In 'Naruto Evil Within' fanfiction, he might be even more of an anti - hero or fully embrace the dark side, perhaps being more ruthless in his pursuit of power. He could be shown as having a different relationship with Naruto, more adversarial and less likely to be redeemed.
Obviously, Harry Potter himself is the central character. Then there are often female characters from the original series. Hermione Granger could be one of them. In the harem scenario, her relationship with an evil Harry would be a major focus, as she might be conflicted between her old friendship and his new evil ways.
In some fanfictions, Avada Kedavra is used as a way to explore the darker side of characters. For example, a character who was previously seen as good might be forced to use it in self - defense, which then causes them to struggle with guilt. It can also be used to create alternate universes where the spell has different effects or consequences.
They could be portrayed as having a bit of good in them. For example, they might be under some sort of dark spell that forces them to act as they do, and if that spell is broken, they could be more like guardians of the wizarding world in a different way.
In fanfiction, dark creatures can be more sympathetic. For instance, a vampire might be shown as a victim of his own condition rather than just a menacing figure. This gives readers a new perspective on these usually feared beings.
Common characters he could meet include an au Ginny who is a powerful seer. There might be a Hagrid who is a tiny, timid man instead of the large, boisterous one we know. He could also encounter an au Sirius Black who is a Death Eater, which would be a shocking twist. Additionally, he may run into an au Professor McGonagall who is more of an artist than a Transfiguration teacher.
Well, in such fanfiction, Harry Potter could meet different versions of Dumbledore. In one universe, Dumbledore could be a dark wizard instead of the wise mentor we know. He may also come across alternate versions of Sirius Black. Maybe in some universes, Sirius is still in Azkaban for a crime he actually committed. Additionally, he could meet different versions of Luna Lovegood, some of whom might have no interest in the strange and wonderful things she loves in the original universe.