Another possibility is an ancient evil that has been awakened. This entity might see Hermione as a threat because of her potential power. So it curses her to stop her from growing stronger. In this case, the antagonist would be very powerful and mysterious, and Hermione and her friends would have to do a lot of research and exploration to find a way to defeat it.
One common theme is the struggle against the curse. Hermione, being a strong - willed character, is often shown fighting to break free from the curse's hold. Another theme is the impact on her relationships. For example, her friendship with Harry and Ron might be strained as she tries to deal with the curse.
One possible plotline could be Hermione trying to find a way to break the curse on her own. She might use her vast knowledge of magic from the library. Another could be her friends, like Harry and Ron, going on a dangerous quest to find the antidote for the curse. And perhaps there's a plotline where the curse has some unforeseen side effects that change her relationships with other characters.
She might find it in an old, forgotten wizarding attic. There could be a whole collection of strange and dangerous magical items, and the cursed knife stands out among them.
There's also 'Hermione's Cursed Adventure'. In this fanfiction, Hermione gets cursed during a dangerous encounter in the Forbidden Forest. The author does an excellent job of showing how Hermione struggles with the effects of the curse while still trying to use her intelligence to find a solution. It has some really exciting plot twists.
Well, perhaps the cursed knife has some special powers that Hermione discovers. It could be that she uses it to break a powerful dark magic spell. For example, the knife might be the only thing that can cut through a magical barrier protecting a dark object.
Cursed fanfiction is a type of fan - created writing that often contains very strange, disturbing, or unconventional elements. It might involve combining characters from different universes in really odd ways, or putting them in situations that are completely against their normal character traits. For example, making a cute and friendly cartoon character into a villain in a very dark and twisted story.
One popular 'Ron Hermione Cursed Child' fanfiction is 'The Unforeseen Bond'. It explores their relationship further after the events of 'The Cursed Child'. It has great character development and interesting plot twists.
The origin of the cursed sword could be from an ancient and evil clan. Maybe they used dark magic to create it, and it was lost over time until Naruto discovers it by chance. For example, it could have been buried in a forgotten tomb that Naruto stumbles upon during a mission.
You can start by looking on fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. Just type in 'Ron Hermione Cursed Child' in the search bar and a whole list of relevant fanfictions will come up.