Well, for one, a good Naruto and High School DxD fanfic should blend the two worlds seamlessly. It can't feel like two separate stories just mashed together. The author should also explore the cultural differences between the two settings. Naruto has a more traditional Japanese - inspired world, while High School DxD has a modern, supernatural - filled world. If the fanfic can find a way to make these differences interact in an engaging way, that's a plus. And of course, the story should have a good flow, with enough action, drama, and character development to keep the readers interested.
A good Naruto and High School DxD fanfic would first have well - written characters. The author needs to understand the personalities of the characters from both series and make them act in a way that is true to their original selves. Also, an interesting plot is crucial. It could be something like a common threat that forces the characters from both universes to work together. For example, a new powerful enemy that neither Naruto's ninja skills nor High School DxD's magic can easily defeat.
For a High School DxD and JJK fanfic to be great, it should have well - developed characters. In High School DxD, the characters have distinct personalities like Issei's pervy yet determined nature. In JJK, Yuji's growth and his complex relationships are important. A good fanfic will build on these traits.
He could be a new type of threat or ally in the DxD world. Since Naruto has such powerful abilities, the fallen angels might see him as a potential weapon or a hindrance to their plans.
One idea could be to create a fanfic where Naruto is somehow transported to the world of High School DxD. He could bring his unique ninja skills and chakra system. Maybe he teams up with Issei to fight against a common enemy. For example, a powerful devil or fallen angel that threatens both the ninja world and the DxD universe.
Power dynamics play a big role too. Naruto is a very powerful ninja, and in the High School DxD universe which is filled with powerful devils, angels, and other supernatural beings, how his power compares and how he uses it is a major aspect. He might have to learn new ways to use his chakra in a world where magic and sacred gears exist.
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.
First, do your research on both universes. Know the characters, their abilities, and the rules of each world. This will help you write more accurately. Then, come up with an interesting plot that combines elements from both. For example, a tournament where Naruto characters and DxD characters compete. Keep the dialogue in character for each one. If you're writing Naruto, he should talk like he does in the anime. The same for DxD characters.
In this fanfic, Naruto's unique abilities like his shadow clones and Rasengan could be combined with the magic and powers in the DxD universe. For example, a fallen angel might be interested in Naruto's chakra and try to use it for their own purposes. Naruto, being the hero he is, would not let that happen and would start a conflict that could lead to an epic adventure.
A fanfic of this nature could explore different themes. One theme could be the clash between different power systems, that is, the ninjutsu from Naruto and the magic in High School DxD. The primordial god connection could act as a bridge or a source of conflict. Another theme could be about Naruto's journey of self - discovery in this new and strange world. He might have to adapt to the different social and power structures in High School DxD while also coming to terms with his new role as someone related to a primordial god.
One possible fanfic could be about Naruto being transferred to the High School DxD universe and his encounter with the Juubi there. Maybe he has to team up with the characters from High School DxD to deal with the threat of the Juubi. For example, Naruto's unique abilities like the Rasengan and Shadow Clone Jutsu could be a great asset in battles within this new universe.
One great 'Naruto - High School DxD' fanfic is 'Naruto in the World of High School DxD'. In this fanfic, Naruto is somehow transported to the world of High School DxD. It's interesting to see how his ninja skills and values from the Naruto world interact with the supernatural and often chaotic world of High School DxD. The author does a good job of integrating Naruto's character traits into the new setting, creating a unique and engaging story.