One character that is frequently paired with Harry in such fanfiction is Sirius Black. Sirius, being Harry's godfather, could be training Harry to use his super speed in combat situations. Also, Luna Lovegood might be paired with Harry. Luna could have some unique insights about Harry's super speed, believing it to be related to some other - worldly magic that she has read about. And of course, Ginny. Ginny could be Harry's love interest who is both impressed and a bit worried about Harry's dangerous new ability.
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.
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.
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.
There might be a forgotten or background character from the original series who is given super speed in the fanfiction. For example, Neville Longbottom could be an interesting choice. His growth throughout the original series could be further enhanced with super speed. He could use it to protect his friends and Hogwarts in unexpected ways, becoming a hero in a different sense compared to his original character arc.
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.
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.
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.
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.
Tony Stark is often paired with Peter Parker in super genius fanfiction. Given Stark's own super - intelligence and technological prowess, they can have great interactions. They can collaborate on projects, with Stark mentoring Peter in some aspects of advanced technology and Peter impressing Stark with his fresh and creative ideas.
Hermione is often paired with Harry. She might help him study and understand the animagus transformation better. Also, Ron could be there, providing his usual comical relief and loyalty. They could get into all sorts of adventures together with Harry as an animagus.