One idea could be exploring the backstory of the 'Prisoner of Sand' character in more depth. Maybe they have a hidden past related to a long - lost shinobi clan in the Sand Village. Another idea is a rescue mission where Naruto and his friends try to free the 'Prisoner of Sand' from some powerful enemy who has captured them for their unique abilities. A third idea could be a story where the 'Prisoner of Sand' has to team up with Naruto to stop a greater threat to both the Leaf and Sand Villages, and in the process, they learn to overcome their differences.
Well, a plot could revolve around the 'Prisoner of Sand' being wrongly accused of a crime in the Sand Village. Naruto, being the one who believes in justice for all, decides to help prove their innocence. Along the way, they discover a conspiracy within the village's leadership that is trying to frame the 'Prisoner of Sand' to gain more power. It could be a story full of mystery, action, and the building of an unlikely friendship between Naruto and this character. Also, perhaps the 'Prisoner of Sand' has a special power that is the key to solving a much larger problem in the ninja world, and Naruto helps them unlock it.
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.
One idea could be exploring what would happen if Sirius Black was recaptured before Harry could prove his innocence. Another could be a story where Peter Pettigrew managed to frame someone else entirely. Or perhaps a fanfic where Hermione uses her time - turning device to go back and prevent Sirius from being sent to Azkaban in the first place.
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.
A great plot could involve Kairi finding an unexpected ally within the prison of darkness. This ally could be someone who was once an enemy but now has a common goal with her. She could also start to understand the true nature of the darkness and find a way to use it to her advantage, rather than being completely overpowered by it.
One idea could be that Ron and Hermione accidentally stumble upon a secret passage in Hogwarts while investigating the mystery of the Prisoner of Azkaban. This passage could lead them to a hidden chamber where they find clues about Sirius Black that no one else has discovered yet.
One idea could be exploring Sirius Black's life more in depth during his time on the run. Maybe he had some secret encounters with other magical creatures that he never told Harry about.
Perhaps the ancient prisoner is actually a wronged hero from the past. Percy discovers this and has to fight against the forces that want to keep the prisoner locked up, all while dealing with the internal politics of the demigod world. The prisoner could hold the key to a new kind of magic or weapon that the demigods need to defeat an upcoming evil. It could also be that the prisoner has a connection to Percy's family history, and by freeing him, Percy learns more about his own heritage and powers.
One interesting plot idea could be a new character being introduced who has a special connection to the Shield in the story. Maybe this character has the power to enhance the Shield's abilities and uses it to protect Hogwarts in a different way than expected.
A great idea for a 'Naruto of the Sand' fanfic is to create an alternate universe where Naruto was actually born in the Sand Village. This would change a lot of the dynamics in the story. He could have different friends, different training methods, and a different relationship with the Kazekage. Also, you could write about a fanfic where the Sand ninjas have to adapt to a new technology that Naruto somehow brings to the village. It could be something like a new type of weapon or a way to enhance their chakra control. Another idea is to make a story about a Sand ninja who goes on a journey to find Naruto in Konoha for a special mission that only Naruto can help with.
One idea could be exploring Prisoner Zero's backstory before being imprisoned. Maybe he was wrongly accused and the oc in the fanfic could be on a quest to prove his innocence.