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.
One possible idea for this fanfiction could be Naruto being transported to the world of High School DxD. He might end up attending the same school as Rias. Given Naruto's strong sense of justice and his combat skills, he could quickly become involved in the supernatural battles and power struggles in that world. He might also form an interesting relationship with Rias, perhaps starting as friends and gradually developing into something more as they face various challenges together.
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.
Issei could develop by learning the discipline and self - control that comes with being an exorcist. This would contrast with his more impulsive devil - side nature. For example, he might have to resist the urge to use brute force and instead use the more strategic and spiritual techniques of an exorcist.
The concept of time manipulation through chrono vision in DxD fanfics can also be related to character development. A character who initially misuses the power, perhaps by relying too much on it and not developing other skills, could face a setback. For instance, they might encounter an enemy who can disrupt their chrono vision. This would then force them to grow and adapt, learning to fight without relying solely on seeing into the future, which makes for an interesting character arc.
To create a memorable OC, give them a unique backstory related to the junkyard. Maybe they grew up there and learned to build things from the scraps, which gives them an edge in the Dxd world. Also, their OP ability can be something that ties in with their gamer side, like being able to hack into magical systems in the Dxd world because they were good at hacking in games.
A smart fem Issei in fanfiction can also bring new story arcs. Instead of just following the typical 'get stronger and fight bad guys' plot, she could be more interested in things like researching ancient magic or finding ways to improve the devil society through her intelligence. This would lead to different types of conflicts and resolutions. Maybe she discovers a way to bridge the gap between different supernatural factions using her knowledge, which would be a very different story from the original where Issei is mainly focused on his own growth and his relationships with his harem.
A writer could also introduce new plot elements related to this. Maybe there's a curse that needs to be broken, and the story revolves around Issei trying to figure out how to break it. This would create suspense and keep the readers engaged.
There Is No Precise Answer Because This Question Is Not Precise Enough. Many web novelists would come up with plots for their novels, but there was no fixed answer to this question.