There could be a group within the Ministry of Magic itself that is corrupt. They might not like Hermione's progressive ideas about the treatment of house - elves and other non - human magical creatures. So they conspire to put her in Azkaban to silence her and maintain the status quo.
Maybe a jealous wizard or witch within the Ministry of Magic. They might be envious of Hermione's popularity and influence among the younger wizards. So they fabricate evidence against her to get her locked up in Azkaban.
One possible plot could be that Hermione was wrongly accused of a serious crime against the wizarding world. Maybe she was framed by a dark wizard who wanted to silence her for her intelligence and knowledge. She might be struggling to prove her innocence from within Azkaban while her friends on the outside, like Harry and Ron, are desperately trying to find evidence to free her.
Harry Potter, of course. His friendship with Hermione is a crucial part of the original story, and in a fanfiction, their bond can be explored even deeper. Maybe Harry discovers a new side of Hermione during the events of Prisoner of Azkaban.
Another possibility is a jealous student at Hogwarts. There are always students who might be envious of Hermione's academic achievements. They could set up a prank or a trap that goes wrong and ends up hurting her. For example, a student who is tired of Hermione always getting the top grades in Potions might tamper with her cauldron during a class experiment, resulting in an explosion that hurts her.
It could be Orochimaru. He has always been interested in Naruto's power. Maybe he locked Naruto in a cage to study his chakra or to use him in some kind of dark experiment.
One interesting theme is the power of friendship. In the 'Prisoner of Azkaban' setting, Harry and Hermione already have a strong bond. Fanfictions often explore how this bond can be deepened and transformed. For example, they might face challenges together that make them realize their feelings for each other are more than just friendship.
One idea could be Hermione discovering a hidden spell in the Prisoner of Azkaban events that helps her protect Harry in a more unique way. For example, a spell that can temporarily freeze time around a small area, allowing them to escape from danger more easily.
One common plot idea is exploring Sirius Black's life more in - depth. Maybe a fanfiction could focus on his time in Azkaban before his escape, showing his mental state and how he coped. Another idea is changing the roles. For instance, what if Hermione was the one who was wrongly accused instead of Sirius? It would create a whole new dynamic.
You can try some popular fanfiction websites like Fanfiction.net or Archive of Our Own (AO3). On Fanfiction.net, you can use the search bar and type in 'Prisoner of Azkaban' to get a list of relevant fanfictions. AO3 also has a great collection and advanced search options to help you narrow down to the exact type of fanfiction you're looking for based on tags such as characters, relationships, and genres.
In the fanfiction, they could be forced to work on a difficult school project together during the events of the Prisoner of Azkaban. As they struggle to complete it, they start to understand each other's strengths and weaknesses better. Ron might realize how brilliant Hermione is not just academically but also in solving real - life problems, and Hermione could see Ron's loyalty and determination in a new light. This new understanding could lead to a deeper connection between them.