They often change the story by making Harry's character more morally ambiguous. Instead of being the pure - hearted hero, he might be tempted by the dark side. For example, he could start using some of the dark magic that the Death Eaters are known for.
These fanfictions usually change the relationships in the story. Harry's relationships with his friends like Ron and Hermione might become strained as he gets involved with the Death Eaters. His interactions with the villains, such as Voldemort, would also be completely different, perhaps more of an equal footing rather than pure enmity.
Fanfictions about Sirius Black as a Death Eater can change the original narrative significantly. For example, it can change the perception of the Marauders. Instead of being the group of friends we know, they might be more divided if Sirius is a Death Eater. Also, Harry's view of his father's friend would be completely different. He might not trust Sirius at all.
These fanfictions can change the power dynamics. In the original story, Harry has certain roles and responsibilities. But in 'Harry and male harem' fanfictions, his relationships with the male harem members can give him different kinds of power or influence. For instance, the male harem members might support Harry in different ways, which could change how he deals with Voldemort or other threats. They also might change the social standing of Harry within the wizarding world, making him more of a central figure in a different way than in the original story.
These fanfictions can also change the relationships between characters. If a pregnancy occurs between two characters who were previously just friends, it can create a more complex dynamic. For instance, Ron and Luna getting together and having a pregnancy could lead to a completely different kind of friendship within the group. It might also introduce new sub - plots related to how they deal with the news, how their families react, and what it means for their future in the wizarding world. The original story was mainly about fighting dark forces, but in these fanfictions, the focus shifts to more personal and family - oriented matters.
Often, they change the original story by allowing characters to avoid tragic deaths. For example, if Harry gets a second chance, he might be able to save his parents or Sirius. This then has a ripple effect on the rest of the story, like changing the relationships between characters. Harry might not be as bitter towards Snape if he can prevent certain events.
They usually change the story by removing Harry as the central figure. For instance, the balance of power at Hogwarts may shift. Without Harry, the Gryffindors might not have that one hero to look up to. And Voldemort's reign could be much more dominant. Also, characters like Neville often become more important as they may be the ones to take on the fight against the Dark Lord.
These fanfictions usually change the original storylines in multiple ways. Firstly, the relationships between characters are redefined. An arranged marriage between Neville and Pansy, for example, would mean that Neville, who was once a shy and overlooked character, has to step into a more prominent role as a husband in a relationship with a Slytherin. This alters the way the houses interact with each other. Secondly, the power dynamics shift. If a less powerful character is arranged to marry a more powerful one, it can lead to a struggle for equality within the marriage. This struggle can then spill over into the wizarding society as a whole, changing how different families and factions interact, which is very different from the original story where the main focus was on the fight between good and evil.
They often add a layer of modern - day realism. In the original story, things like child abuse at the Dursleys' are more in the background. But in these fanfictions, it becomes a central issue. For example, they might have the Dursleys face legal consequences much earlier in the story.
Well, if James is a Death Eater in fanfiction, it completely alters the dynamic at Hogwarts. James would no longer be part of the group fighting against Voldemort. This would mean that many of the events that happened because of the Marauders' resistance to the Death Eaters wouldn't occur. For instance, the creation of the Marauder's Map might not have been for good reasons. And Lily's relationship with James would be much more complex. Maybe she was initially trying to save him from the dark side, but failed.
They change it a great deal. For starters, Harry wouldn't be an orphan. He would grow up with his parents, which would completely change his personality. He might be more confident and less brooding. Also, the whole dynamic of the wizarding world would be different. There would be no need for Dumbledore to have as much control over Harry's life. James and Lily could have their own influence on how the wizarding world is run.
Often, they change the original story by giving Harry a fresh start. For example, if in the original he lost someone important, in the fanfic with his regeneration, he might get a chance to save that person. His relationships can also be different. Maybe he becomes closer to some characters he was only acquaintances with before.