A possible crossover could involve the plotlines of both worlds. The threat of Akatsuki in Naruto could be related to some of the power struggles in Highschool DxD. For instance, if the Akatsuki were after the Sacred Gears for some reason. This would force the characters from both universes to team up, leading to some exciting battles and character development as they learn from each other's strengths and weaknesses.
One popular crossover might be the exploration of the unique powers. For example, Naruto's jutsu in the Highschool DxD world could create interesting scenarios. His shadow clone jutsu could be used in battles against the devils or fallen angels in the Highschool DxD setting. Another aspect could be the character relationships. Naruto's friendly and determined nature could form unique bonds with the characters in Highschool DxD like Issei. This could lead to new storylines where they team up to face common enemies or help each other grow in power.
The female characters from Highschool DxD, like Rias, would be intrigued by the unique personalities of the Naruto characters. Rias might see potential in some of them to join her peerage. And the Naruto girls, like Sakura, would be a bit shocked at first by the more revealing outfits and flirty nature of some of the Highschool DxD characters. But over time, they would bond over things like protecting their friends and the school. The Naruto boys would respect the power of the Highschool DxD devils and might even try to incorporate some of their fighting strategies into their own ninja combat styles.
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.
In some Highschool DxD and Naruto crossover fanfictions, Naruto might be depicted as a god - like figure. This could be due to his extremely powerful abilities in the Naruto universe, such as his vast chakra reserves, multiple jutsu, and his status as a hero in his own world. Writers may take these aspects and amplify them in the Highschool DxD setting, where the power levels and the concept of beings with god - like powers already exist. So, it's possible for Naruto to be seen as a god in such fanfictions.
In such a fanfiction, it could be that Issei is bashed because he represents a different kind of hero compared to what Naruto stands for. Naruto is all about self - sacrifice and believing in others no matter what, while Issei is more about his own desires and power - seeking in a way. So when these two worlds collide in the fanfic, Issei might be made to look bad in comparison. Maybe the story has Naruto characters like Sasuke or Kakashi giving Issei a hard time because they don't approve of his behavior.
Yes, there are some interesting ones. You can check out fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'rikudou naruto highschool dxd' and you'll likely find a variety of stories with different takes on combining the elements of Naruto and High School DxD.
One interesting plot could be Naruto being summoned to the world of Highschool DxD. His unique ninja skills and chakra would be a huge shock to the devils, angels, and fallen angels in that world. He could end up forming an unlikely alliance with Issei, perhaps teaching him some of his ninja techniques in exchange for learning about the Sacred Gears. They could then face a common enemy together, like a powerful devil who wants to use Naruto's power for his own evil plans.
Perhaps in the fanfiction, Naruto is a new student at the Highschool DxD. He quickly becomes friends with Velena Beal. As the story progresses, they discover that there are dark secrets in the school related to an ancient artifact. This artifact has the potential to change the balance of power in both Naruto's world and the Highschool DxD world. Naruto and Velena then embark on a journey to find and protect the artifact from falling into the wrong hands. Along the way, they face many challenges, including battles with other students who have their own motives regarding the artifact.
A plot could revolve around Naruto attending Highschool DxD as an exchange student. He would be the odd one out, with his orange jumpsuit and headband. The students at the school would be curious about his powers and his world. Naruto could end up in a love triangle between a devil girl and an angel girl, just like Issei often finds himself in romantic entanglements. He would have to navigate the complex social and power dynamics of the school while still staying true to his ninja way.