Perhaps in the fanfiction, Hermione turns into a centaur because she enters an enchanted forest that has a curse on it. As a centaur, she discovers new magical abilities that are unique to centaurs. She might use these newfound abilities to help Hogwarts when it's in danger, all while trying to find a way to turn back to her human form.
In this fanfiction scenario, Hermione could be turned into a centaur by a powerful dark wizard who wants to use her new form against Hogwarts. But instead of being a victim, Hermione, in her centaur form, uses her intelligence and knowledge of magic to outwit the dark wizard. She could also form an alliance with the centaur tribe in the Forbidden Forest and together they fight against the dark forces.
One idea could be that Hermione turns into a centaur as a result of a misfired spell during a Defense Against the Dark Arts class. She could then struggle to adapt to her new form, having to deal with the physical differences like running on four legs and having a horse - like body. Meanwhile, her friends Harry and Ron would be trying to find a way to reverse the spell.
Well, as a centaur, Hermione would likely gain some centaur - specific magical powers. She could use her enhanced speed and strength to explore areas that were previously difficult for her as a human. And she might communicate with other centaurs in a way that reveals new magical secrets about Hogwarts or the Forbidden Forest.
Another possibility is that Hawkeye is on a mission in a world where magic exists on the fringes. He meets Hermione, who is researching ancient magical artifacts that could have an impact on the Muggle world. They start off distrustful of each other but as they learn more about their respective worlds, they form a bond and work together to protect both worlds from a common enemy.
One idea could be that Hermione turns into a Nunbu as a result of a magical experiment gone wrong. Maybe she was trying to study a new form of transformation magic and accidentally triggers this strange transformation. Then she has to figure out how to reverse it while dealing with the unique abilities and limitations of being a Nunbu.
One idea could be Hermione discovers she's the Chosen One when she stumbles upon an ancient prophecy in the restricted section of the library. This prophecy was hidden away for centuries and she realizes it speaks of her. She then has to face a series of trials alone, without the support of Harry or Ron at first, as they are skeptical. This could lead to her growth as a character and show her independent strength.
One idea could be a crossover where Jasper Hale, with his vampire abilities, senses Hermione's powerful magic. They meet when the Cullens move to the UK for some reason. Jasper is intrigued by Hermione's intelligence and her ability to handle complex situations. They start to form an unlikely friendship which gradually turns into a deeper relationship as they learn more about each other's worlds.
One idea could be that when Hermione turns into a boy, she has to deal with different social dynamics in Hogwarts. For example, she might be treated differently by the boys in Gryffindor. Some might be more competitive with her, while others might befriend her in a new way. In the fanfiction, it could explore how she uses her now - male identity to her advantage in magic studies, perhaps being able to participate in all - male magical dueling clubs or something similar. And she could also have an interesting time trying to hide this transformation from her professors, especially McGonagall who is very perceptive.
One great pairing for Hermione Granger in crossover fanfiction could be with Doctor Strange. Their intelligence levels are quite high. Hermione's magical knowledge combined with Strange's mastery of the mystic arts would make for an interesting dynamic. They could solve complex magical - mystical problems together.
One idea could be that Hermione is raised in secrecy by someone who knew Voldemort's true identity but didn't want her to follow his dark path. She discovers her true parentage through a series of mysterious events, like finding an old diary of Voldemort's that reveals secrets. Then she has to struggle with her own identity, whether to embrace the part of her that is related to Voldemort or completely reject it and continue to fight for good.
Another could be a cross - over where Hermione stumbles upon Forks while on some sort of international magical research. She meets Edward and they start to exchange knowledge about their different worlds, like Hermione teaching Edward about complex spells and Edward sharing vampire lore.
A popular idea is a post - war fanfiction where they help to rebuild the wizarding world. They could be involved in projects like restoring Hogwarts or creating new magical educational programs. This gives a chance to show their growth from students to leaders in the wizarding community.