One possible scenario in this fanfiction could be Naruto having his unique ninja skills in the Highschool DxD world. His godlike abilities might make him stand out among the devils and other supernatural beings. He could use his shadow clone jutsu for various strategic purposes, like infiltrating devil strongholds or getting out of tricky situations during the school's chaotic events.
There could well be. Fanfiction writers often like to explore crossovers and unique concepts. However, not all fanfic writers might be interested in combining Naruto with 'Highschool DxD' in a certain way, so there are likely to be some that fit the 'Naruto not a devil highschool dxd fanfiction' idea. You might have to dig a bit through different fanfic archives to locate them.
One characteristic could be that the story remains true to the Naruto universe's tone and themes. It would likely have Naruto dealing with his own set of challenges like fighting against the Akatsuki or protecting his village. It wouldn't introduce the harem - like or devil - based elements from 'Highschool DxD'. Also, the characters would be from the Naruto world, with their own personalities and abilities intact, without any 'Highschool DxD' - influenced changes.
Issei could be a likely hero in such fanfiction. Even though he has a devil side, his human side might make him conflicted about the actions of some devils. He could turn against the devils who are causing harm and use his powers to bash them in order to protect his friends and the school.
Obviously, the third devil would be a main character. But also, characters like Issei could still play a major role. They might interact with the third devil in various ways, such as training together or getting into conflicts. Another potential main character could be a new character that you introduce specifically for this fanfiction. Maybe a mysterious transfer student who has some connection to the third devil's past or powers.
One idea could be exploring a new power that the third devil discovers. For example, a unique ability to manipulate time on a small scale during battles, which would add a whole new dimension to the fight scenes. Another idea is to focus on the third devil's relationships with other characters in a different way. Maybe the third devil forms an unexpected alliance with a group that was previously an enemy, leading to some really interesting character development and plot twists.
Rias Gremory is also a fan - favorite. Fanfictions could focus on her leadership skills within the devil community at Kuoh Academy. For instance, stories could be written about how she deals with new threats to her peerage or how she tries to strengthen her position among other devil clans.
One idea could be a new devil character arriving at Kuoh Academy with a unique power that challenges the existing power dynamics among the devils there. For example, a devil who can manipulate time in small increments during battles, which would make for some really intense and strategic fight scenes.
Well, the plot could center around Naruto being a godlike figure who decides to attend the high school in the DxD world to understand the devils better. He ends up getting involved in a conflict between different devil factions. His Naruto - like determination and his unique powers, which are a blend of his original ninja powers and new devil - like abilities, help him to resolve the conflict and bring peace to the school. He might also make some good friends among the devils and other supernatural beings, which changes his perspective on them.
First, you need to know the characters well from all three universes. Naruto is a determined ninja with a big heart, Dante is a cool and cocky devil hunter, and the characters in Highschool DxD have their own unique supernatural abilities. Then, think of a good plot. It could be a simple story like they all team up to fight a powerful enemy that threatens all their worlds. Or it could be more complex, like a mystery that involves the different power systems of each universe.