A potential plotline could be Naruto arriving in the Highschool DxD world and being mistaken for a new type of devil or other supernatural being due to his 'dark godlike' nature. He would then have to prove his intentions and find his place in this new world. Another plotline could involve Naruto using his skills to train the characters in Highschool DxD in combat, similar to how he trained his friends in the Naruto world.
In this fanfiction, Naruto's 'dark godlike' form might change the power balance in Highschool DxD. Since Naruto has always been about growth and power - up in his original story, in this crossover, he could quickly rise to a very high - level position. His values from the Naruto world might clash with the values in Highschool DxD. For instance, his belief in friendship and hard work could be a contrast to some of the more self - serving or power - hungry characters in Highschool DxD. This could lead to some interesting story arcs.
One idea could be that Naruto is somehow transported to the world of Highschool DxD. He could use his ninja skills and chakra in the new world, maybe even teach some of the characters there a thing or two about combat. For example, he could show Issei how to better control his power using chakra control techniques.
The storylines can be combined by creating a common threat. Suppose an enemy emerges that is interested in both the power of the Bijuu and the power sources in Highschool DxD. This would force the characters from both universes to team up. Also, the cultural differences between the Naruto world and the Highschool DxD world can be explored. Naruto could introduce concepts like ninja clans and shinobi training to the DxD characters, while they could introduce him to the complex social hierarchies and supernatural politics in their world.
Well, in such a fanfiction, Dark Naruto might use his powerful and often shadowy abilities to outwit Rias. Maybe he'd expose some of her less - than - noble actions in the Highschool DxD world. He could easily overpower her in battles, using his ninja skills and the dark powers he has. For example, his shadow clones could be used to confuse Rias and her peerage while he strikes from the shadows.
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.
A fanfiction idea could be that Lucifer from the Highschool DxD universe somehow ends up in the Naruto world. In the Naruto world, he could be seen as a powerful and mysterious figure. He might interact with the ninja clans and shinobi, and his powers could be both feared and respected. He could also have some kind of connection with the tailed beasts or the Sage of Six Paths. The story could revolve around how his presence disrupts or changes the balance of power in the Naruto world.
The appeal lies in the mash - up of different elements. It's like a buffet of cool concepts. You get the action - packed ninja world of Naruto, the unique sword powers of Zanpakuto, and the supernatural high school setting of Highschool DxD. It's a chance to see your favorite characters in new and unexpected situations.
A more complex fanfiction could be about a joint mission between the two universes. The leaders of both worlds realize that there is a common threat that only the combined forces of Highschool DxD and Naruto can defeat. So, they send their best characters, like Rias and Sasuke, to work together. This would involve a lot of character development as they learn about each other's cultures and powers.
One idea could be a crossover where Naruto characters are transported to the world of The Highschool of DxD. For example, Naruto himself could end up at the high school and his ninja skills would be quite a shock to the devils and other beings there. He might get involved in the Rating Games, using his shadow clones and other jutsu to his advantage.