An interesting idea is that when Madara is sealed, his chakra is spread across the ninja world. Naruto has to go on a journey to collect all these fragments of chakra to prevent Madara from ever being resurrected. Along the way, he meets different clans who have been affected by Madara's actions in the past and they either help or hinder his quest.
Perhaps in the fanfiction, Madara is sealed but his consciousness lingers. He starts to communicate with Naruto in his dreams, trying to persuade him to release him. Naruto, being the kind - hearted person he is, is tempted by Madara's words which seem to offer solutions to the ninja world's problems. But he has to resist as he knows the danger Madara poses. This would be a great internal conflict for Naruto to deal with.
One plot idea could be that the seal on Madara contains a hidden power that starts to leak out and affect the surrounding area. This causes strange phenomena, and the characters have to figure out how to stop it without fully releasing Madara. Another idea is that a character has a vision of Madara breaking free from the seal in the future, and they embark on a journey to prevent it by strengthening the seal in the present.
In some Naruto fanfictions, Madara might be sealed through a powerful jutsu created by the main character. For example, the protagonist could combine different elemental chakra natures to form a unique sealing technique specifically designed to counter Madara's power.
One interesting idea could be how the sealed hatred affects Naruto's relationships. Maybe it makes his friends more cautious around him, or it could create new rivalries. For example, if the hatred seeps out in small ways, it might cause misunderstandings among his comrades in the Hidden Leaf Village.
In some 'naruto sealed gender fanfiction', the story might focus on how the ninja world reacts to Naruto's new gender. For example, some characters might be more accepting while others could be more hostile, which would create new plotlines and tensions.
One interesting idea could be the combination of Naruto's world with another popular anime world. For example, if it's crossed with One Piece, Naruto might use his sealing jutsu on Devil Fruits to prevent their misuse. It could also involve Naruto being sealed in a different realm from another anime and having to find a way back while facing new challenges.
One idea could be exploring how Hashirama's sealing affects the balance of power in the ninja world. For example, other villages might see it as an opportunity to gain an edge over Konoha.
One interesting idea could be exploring the power dynamics between Madara and Naruto. Since Madara is a very powerful and experienced shinobi, and Naruto has his own unique strength. Their interactions might lead to some intense and unexpected plot developments.
One idea could be a story where Madara and Hashirama are reborn in the modern ninja world and have to navigate the new technologies while still having their old grudges and loyalties. They might initially be confused but then slowly adapt and perhaps even find a way to resolve their age - old differences.
One idea could be that Madara takes Naruto under his wing to train him in a different style of combat, leading to Naruto having a unique set of skills. This would change Naruto's relationships with his friends as they might be initially skeptical.
A fanfiction could focus on a character who is immune to the effects of Madara's Sharingan. This character could be a new type of ninja from a far - off land with a unique chakra nature that counteracts the Sharingan's genjutsu and other abilities. The story could be about how this character challenges Madara and changes the power dynamic in the Naruto universe.