Ichigo could be a game - changer. His Hollow - like powers might be mistaken for some sort of demonic or otherworldly ability in the Highschool DxD setting. This could lead to both misunderstandings and interesting interactions with the characters there.
One possibility could be that Ichigo's powers would make him a very unique and powerful character in the Highschool DxD universe. His zanpakuto abilities and high - level combat skills could give him an edge in the battles against the devils and other supernatural beings in that world.
One great Issei fanfiction is 'Raising Hell with Issei'. It shows a different side of Issei's growth and his adventures in the Highschool DxD universe. The story has some really interesting plot twists that keep you hooked.
One great 'Op Naruto Highschool DxD' fanfiction is 'Naruto in the World of Highschool DxD'. It has an interesting plot where Naruto's skills and abilities from his own world blend well with the unique setting of Highschool DxD. The story focuses on how he adapts to the new environment and the relationships he forms with the characters there.
Well, Naruto's positive attitude and never - give - up spirit would contrast with some of the more self - interested characters in DxD. He could inspire them to be better. And his unique abilities like the rasengan could be a new weapon in the battles against the various devils and other supernatural beings in DxD.
A great fanfiction could involve Naruto's overpowered (op) abilities being introduced into the Highschool DxD universe. For example, Naruto's shadow clone jutsu could be used in the battles at the high school in DxD. His ability to harness chakra might be a new form of power in that world.
One common theme is power escalation. Since Issei is OP in these fanfictions, the story often focuses on how he continues to gain and control his ever - increasing power. Another theme is harem - related, as in the original Highschool DxD, Issei has a harem. In the fanfictions, his OP status might attract even more characters to his harem, and the dynamics within the harem change because of his new power level.
A fanfiction could focus on Ichigo attending the school in Highschool DxD. His presence would surely disrupt the normal balance. He might not be interested in the whole 'devil' and 'angel' thing at first, but gradually get involved. He could also introduce some of his Soul Reaper training methods to the students there, which would be very different from what they're used to.
First, you need to understand the characters well. For Ichigo, know his personality traits like his determination and his sense of justice. For the Highschool DxD characters, understand their hierarchies and their goals. Then, come up with a unique plot. It could be a battle - oriented story where Ichigo and the DxD characters fight a powerful enemy together. Or it could be a more slice - of - life story where Ichigo adapts to the strange new world of DxD.
Shirou would fit in as a powerful and unique addition. His combat skills and magecraft would make him a formidable ally or opponent. He could use his projection abilities to create various weapons and tools, which would be very useful in the battles that often occur in the Highschool DxD world.