Luna Lovegood is also a popular character to be paired with Harry in these fanfictions. Her unique perspective and Harry's new - found knowledge from going back in time could lead to some really interesting adventures. They could discover new magical creatures or secrets about the wizarding world.
Sometimes, even Severus Snape is paired with Harry in a more positive light in 'harry goes back' fanfiction. Since Harry has the chance to go back, he might be able to understand Snape's motives better and they could end up working together against common enemies, changing the course of the wizarding world's history.
Obviously, Harry himself is the central character. Hermione is also often involved as she is Harry's friend. Ron too, as they are a trio. Dumbledore usually plays an important role as he is the headmaster. Snape is also a popular character in these fanfictions as Harry might try to change their relationship. And of course, Hagrid, who is always there for Harry in the original story and could be involved in new and different ways in the fanfiction.
Hermione is often paired with Harry. She could be the one helping Harry understand the scientific or magical theories behind his super speed. Another popular character is Ron. Ron might be in awe of Harry's new power and get into some comical situations while trying to keep up with Harry. And then there's Dumbledore. Dumbledore could be guiding Harry on how to use his super speed for the greater good of the wizarding world.
Hermione is often still a very important character paired with female Harry. Their friendship could be even more complex and deep, as they support each other through the challenges at Hogwarts. Ron is also a common character paired with her. Their relationship might develop in a different way, perhaps with a bit more of a romantic undertone compared to the original. Draco Malfoy is another popular one. There could be a more interesting dynamic between them, with Draco being both attracted and antagonistic towards her at the same time.
In many fanfictions, Neville Longbottom's son or daughter is paired with Harry's daughter. Given Neville's importance in the wizarding world, their children's relationship can be really engaging. They could be partners in a herbology project, and through that, develop a deeper connection. Also, the children of Luna Lovegood are sometimes paired with Harry's daughter. They might share an interest in the more esoteric aspects of magic and go on adventures to discover new magical creatures or phenomena together.
Hermione is often paired with female Harry in a strong friendship way. They can support each other through all the challenges at Hogwarts. Ron can also be part of their group, and there might be a more platonic relationship between female Harry and Ron. Dumbledore is always an important character in relation to female Harry, guiding her and protecting her as he did with male Harry.
As I mentioned before, Draco. The whole idea of a female Harry and Draco having some sort of relationship, whether it's a begrudging friendship or a full - blown romance, adds an interesting twist to the original story. Their family rivalries and different personalities create a lot of potential for interesting interactions.
Severus Snape could also be a character often paired with Bellatrix. They were both on Voldemort's side, but Snape had his own hidden motives. Fanfiction might explore a relationship between them, perhaps a power struggle or a secret alliance that also involves Bellatrix's relationship with Harry in some way.
Hermione Granger is often paired with Harry Potter's long - lost sister. Hermione's intelligence and knowledge of magic can complement the sister's unique abilities. They can form a strong trio with Harry, with Hermione providing the logical solutions and the sister bringing in her special powers.
Hermione is another common character. Since she is always so intelligent and resourceful, Harry might turn to her for help in understanding the implications of time travel. They could work together to change certain events, like preventing the release of some dark magic that they later had to face. And of course, Ron would also be around. His loyalty and friendship would be a source of support for Harry as he navigates this new timeline.
Gray is also a popular character to be paired with Natsu in these fanfictions. Their friendly rivalry can take on new dimensions when Natsu travels back in time. They could end up working together in unexpected ways in the past.