Another plotline might be exploring Naruto's past more deeply. Maybe there are secrets about his parents that were never fully revealed in the original. In the fanfiction, he could discover something new about his father's time as Hokage or his mother's Uzumaki heritage that changes his perspective on his own powers and responsibilities.
Yes, there might be such fanfictions out there. Fanfiction writers often create crossovers where they put characters from different universes like Naruto and High School DxD together and come up with various scenarios, including ones where Naruto could potentially 'kill' a character from the DxD universe. However, the quality and nature of these fanfictions can vary greatly.
In a Naruto and High School DxD fanfiction, there could be a scenario where the protagonists of both stories meet in a neutral dimension. Issei from High School DxD might be intrigued by Naruto's ninja skills and determination. Naruto, in turn, could be curious about Issei's Sacred Gear. They could start training together, sharing their knowledge and skills, and ultimately have to face a common enemy that threatens both their worlds.
In fanfiction, an older Naruto may have a more refined sense of leadership. He has seen more, experienced more battles and political situations. So, he might be more diplomatic in his approach compared to his younger self.
One possible fanfiction could be about a crossover where the characters from Highschool DxD and Naruto are transported to a world where they meet Gabriel. Maybe they team up to fight a common enemy. For example, the devils from Highschool DxD and the ninjas from Naruto could combine their powers under Gabriel's guidance to defeat an ancient evil that threatens all three of their realms.
In a Highschool DxD - Naruto crossover fanfiction with Ophis, she could form an alliance with some of the Akatsuki members. They might be interested in her power and knowledge. Ophis could use this opportunity to learn about the unique chakra system in Naruto. This could lead to a series of battles and power - up scenarios as she tries to adapt to this new world and the Akatsuki tries to use her for their own goals.
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.