Often, it changes the original plot by allowing Harry to prevent certain deaths. For example, he might go back in time to save Sirius Black or Dumbledore. This alters the emotional landscape of the story significantly.
In 'Harry back in time fanfiction', it usually changes the plot by giving Harry a chance to correct his past mistakes. He could go back to when he first started at Hogwarts and be more confident, make better friends, or study magic more effectively. This in turn affects how he faces Voldemort later on. Also, he might be able to change some of the early misunderstandings between different houses, like Gryffindor and Slytherin. This can lead to a completely different Hogwarts environment and a different outcome in the battle against the Dark Lord.
These fanfictions change the plot by introducing new relationships. Since Harry is back in time, he might form different bonds with characters. For instance, he could befriend characters who were initially his enemies or have a closer relationship with characters he only knew casually in the original story. This new dynamic can then impact how events unfold. Harry might also be able to influence the development of magic at Hogwarts. He could introduce new spells or magical concepts he learned from the future, which would completely change the magical world as it was originally presented in the books.
The fanfiction might also change the original plot by introducing family - centered subplots. Since Harry has a sister, there could be more focus on the Potter family history and legacy. Maybe the sister discovers something about their parents that Harry didn't know before. This can lead to a whole new set of quests and revelations, as they try to understand their family's past better. Also, the sister's existence can influence the way Voldemort views the Potters. He might see her as another threat or as a means to get to Harry, which changes the nature of their conflict.
Well, a 'Harry raised by Andromeda' fanfic can completely transform the original story's plot. Andromeda, being a Black, has her own connections and knowledge of the wizarding world. She can introduce Harry to different aspects of magic and magical families that he might not have known otherwise. His growth as a wizard is different. He may not rely as much on his friends for emotional support as he gets it all at home. This can change the dynamics of his friendships at Hogwarts. Also, in the battle against Voldemort, Harry may have different resources and allies due to Andromeda's influence.
In many 'harry potter super powerful fanfiction', the power - up of Harry (or other characters) often changes the power dynamics in the story. For example, if Harry is super powerful, he might not need the help of his friends as much, so the strong bond of friendship that was central in the original story could be weakened. Also, the villains would have to be much stronger or use different tactics to oppose him. The challenges he faces become different, not just the typical duels and mysteries but perhaps more on a cosmic or world - changing scale.
The fanfiction might change the plot in terms of Harry's relationships. Maybe his new ability with the Nuibari makes some of his friends jealous or in awe of him. Also, it could attract the attention of new characters or factions who are interested in the Nuibari. This could create new alliances or rivalries for Harry. For example, some dark wizards might want to steal the Nuibari from him, leading to new conflicts. And in his journey to master the Nuibari, he might have to visit new places or seek help from unexpected sources, thus diverging from the original plot.
Well, it can change the relationships in the story. Harry's relationship with Sirius, for instance, might not be as father - like as in the original. Since Lily is back, Harry has his real mother, and Sirius may take on a different role. Moreover, it can also affect the power balance. With Lily's return, the Order of the Phoenix could have a stronger magical force at their disposal, potentially changing the outcome of battles.
The Time Turner can completely change the plot by allowing characters to redo actions. For instance, if a character fails a mission in the original plot, with the Time Turner, they can go back and try again, which might lead to a different outcome for the whole story.
It adds a new type of creature. The werepire concept changes the magical world by introducing a different kind of threat or ally. Harry might have to face different challenges related to this new entity.
A fanfic with Cedric and Harry as brothers would change the Hogwarts experience for both of them. They could share a dormitory or have special family - related privileges at school. Their bond as brothers would likely make them more of a united front against the likes of Voldemort. Instead of Harry being the sole focus of Voldemort's attention, Cedric would also be in the crosshairs. This would lead to different strategies and plot developments. The Weasley family might interact with them differently too, as they would be related to Harry in a different way. And the relationship between Harry and Cho Chang (who was Cedric's girlfriend) would be completely reimagined, adding a whole new layer of complexity to the story.
In a 'Harry Potter Dies' fanfiction, the plot often takes a dark turn. The hope that Harry represented is gone. This could lead to the Ministry of Magic falling apart, as they had put so much faith in Harry. Hogwarts might also become a more dangerous place as the students lose their sense of security. The Death Eaters could become bolder, and the remaining good characters have to scramble to hold things together. It can also lead to new alliances being formed as characters who were once on the sidelines are now forced into the fray.
Often, it changes the power dynamics. Instead of growing up with the Dursleys, Harry might grow up in a completely different environment, which gives him different skills and knowledge. For example, if he's raised by magical creatures, he could have a deeper understanding of nature magic.