One plot idea could be that Naruto is somehow transported to the world of Final Fantasy 13. There, he meets the characters and due to his unique abilities and charm, a harem starts to form around him. He could use his ninja skills to help the characters in their battles against the fal'Cie. Another idea is that the characters from Final Fantasy 13 are brought to the Naruto world. The different cultures and powers collide, and as the FF13 characters adjust, they are drawn to Naruto, creating a harem situation. The harem members could then team up with Naruto to protect both worlds from common threats.
In a harem fanfiction of Naruto and Final Fantasy 13, the story could start with Naruto being summoned by a powerful being in the FF13 world. The female characters there see him as a strange yet powerful ally. Lightning, for example, might be initially skeptical but gradually come to respect Naruto. Fang could be intrigued by his physical strength. As they interact more, a harem dynamic develops. Naruto's goal could be to find a way back home while also helping the FF13 characters with their fight against oppression. Along the way, romantic and comical situations can occur within the harem.
A great Naruto Final Fantasy fanfiction idea is to combine the magic systems. In this story, shinobi could learn to use Final Fantasy - style magic, like black magic for offensive spells and white magic for healing. Or perhaps a plot where the Akatsuki is after a powerful crystal from the Final Fantasy world that could grant them ultimate power. Also, a fanfic about a character from Naruto traveling through different worlds of Final Fantasy, facing the challenges and enemies in each world.
One idea could be exploring the backstories of the minor characters in more depth. For example, the story of the civilians in Cocoon who were affected by the events. Another could be a what - if scenario, like what if Lightning had made different choices at certain key moments. And a third could be focusing on the relationship between Fang and Vanille before they became l'Cie.
The OC could be a descendant of a powerful clan that was thought to be extinct. Their presence in the Naruto world stirs up interest among many characters. The OC's knowledge of ancient jutsu and their kind heart draw in characters like Kakashi, Shikamaru, etc. into a harem. The OC then has to navigate the complex relationships while also trying to keep their clan's secrets safe.
Perhaps the fanfiction could explore how the daimyo's harem affects the political situation in the Naruto world. The different members of the harem might have connections to various factions, and the daimyo has to balance these relationships to maintain peace.
Maybe Naruto was born blind in this fanfiction. However, his determination and positive attitude attract a group of girls. They see his inner strength and beauty, and as the story progresses, Naruto trains hard to become a powerful ninja in his own way, and the harem girls are there to cheer him on and help him out in battles.
Perhaps in this fanfiction, Haku survives and Naruto, through his unique ability to see the good in people, helps Haku fully integrate into the village. As a result, more female ninjas are attracted to Naruto's inclusive nature, and Haku becomes a central figure in a harem - like scenario where they all share a special connection with Naruto. This connection could be based on mutual respect and admiration for Naruto's growth as a ninja.
One idea could be Naruto forming a unique bond with each member of the harem in different ways. For example, with Konan, he might discover her love for art and they could bond over creating origami together. Another could be Naruto teaching his harem members some of his ninja techniques, which would lead to interesting training sessions and character development.
One plot idea could be that Naruto somehow gets transported to the world of Arrancars. He then starts to form relationships with different Arrancar characters, leading to a harem situation. Maybe he uses his ninja skills to protect them from other threats in their world, and in the process, they all fall for him.
Perhaps in the fanfiction, Naruto and Ayame start a mission together that leads to them getting stranded in a strange land. There, they gradually form a harem as they meet various characters who are attracted to their unique qualities and the bond between them.
One idea could be that the main character, who has traits from both Naruto and Yugioh universes, accidentally creates a portal that brings together characters from both worlds into a shared space. In this new space, a harem starts to form around him as characters from different backgrounds are intrigued by his unique abilities. Another plot could involve a tournament where the rules are a mix of Yugioh duels and Naruto - style battles, and the winner gets to be part of a special harem.