Perhaps a fanfiction where Naruto becomes a ronin after some kind of political upheaval in Konoha. He then has to decide whether to return and fight for his village or continue his solitary journey, while also uncovering secrets about his past along the way.
One idea could be a story where Naruto, as a ronin, travels the world to learn new jutsu from different hidden villages. He could encounter unique characters and face challenges that test his skills and beliefs.
One plot idea could be a crossover where the Naruto characters are somehow transported to the era of the 47 Ronin. They could use their ninja skills to help the Ronin in their quest, like Naruto using his shadow clones to gather information. Another idea is that the spirit of the 47 Ronin could possess some of the Naruto characters, leading to changes in their personalities and abilities as they carry out a similar mission of revenge in the Naruto world. A third idea might be that a new character inspired by the story of the 47 Ronin joins the Naruto universe and has to prove themselves among the ninja.
In Naruto Ronin Ninja fanfiction, the concept of Naruto losing his connection to Konoha and becoming a ronin can lead to some great character development. He could struggle with feelings of loneliness and identity. Maybe he meets other lost souls on his journey, and together they form an unlikely bond, facing challenges that are different from what he faced in Konoha. This could also explore how Naruto's view of the ninja world changes when he's not tied to a particular village.
One idea could be to cross them over with a modern superhero team. The Ronin Warriors could learn new fighting techniques from the superheroes and vice versa. It would be cool to see how their different powers and armors interact.
One interesting idea could be the combination of Naruto's ninja skills with mecha technology. For example, Naruto might use his chakra to power up the mecha in unique ways. Another idea could be the new enemies that are created specifically for this mecha - Naruto concept, like robotic shinobi that require different combat strategies compared to normal foes. Also, the design of the mecha Naruto itself can be really cool, perhaps with features inspired by the Nine - Tails.
One common theme is the clash of cultures. The samurai and ninja cultures are different, so in fanfiction, there's often exploration of how they interact. For example, a ronin trying to adapt to ninja ways or vice versa.
Often, in these fanfictions, there are new character relationships. For example, Naruto characters might form unexpected alliances or rivalries with the Ronin Warriors. This can lead to some very interesting plot twists and character development. Also, the fanfictions can explore different moral and ethical concepts as the two different cultures collide. The Ronin's honor - based system might contrast or complement the ninja's way of life in Naruto. Another aspect is the new combat styles that emerge when the powers of Naruto characters and Ronin Warriors are combined. This can make for some really epic battle scenes.
Another idea is that Aizen somehow ends up in the Naruto universe during the time of the Fourth Great Ninja War. He could try to manipulate both sides for his own gain. But Naruto, with his ability to see the good in people, might try to reason with Aizen and show him a different path. It could be a story of redemption or a great battle if Aizen refuses.
In a 'Naruto Mermaid Fanfiction', the mermaids could be in danger from an evil organization that wants to capture them for their precious scales. Naruto teams up with a mermaid princess to stop this threat and in the process, they learn about each other's worlds.
One idea could be a crossover where Naruto and Pucca end up in the same world due to a strange ninja jutsu gone wrong. Naruto is confused by Pucca's constant chasing of Garu, and he tries to help Garu escape in his own Naruto - style way.
Well, you could write a fanfiction where the Nine - Tails in Naruto has some sort of connection to a powerful entity in the Seraphim universe. This connection could lead to a series of events that require Naruto and the Seraphim characters to work together. Or perhaps a character from Seraphim is reincarnated as a ninja in the Naruto world and has to adapt to the new way of life while still having some of their Seraphim abilities.