Well, perhaps a plot twist could be the mixing of the two worlds' forms of magic. Naruto's world has its own kind of jutsu - based magic, while High School DxD has demonic and angelic magic. If these magics were to merge in some characters, it would create really unique abilities. For instance, a character could use a jutsu while also having the ability to summon angels or devils. Another interesting plot twist could be that the Nine - Tails (from Naruto) somehow gets involved in the Rating Games in High School DxD. It would be a huge advantage or a major disruption depending on how it's handled. And what if a character from High School DxD learned the Shadow Clone Jutsu? They could use it for all sorts of mischief or strategic advantages in their own world.
A possible plot twist is that the characters from High School DxD initially underestimate Naruto due to his neglected state. But then they find out that he has a deep understanding of loyalty and friendship from his time in Konoha. This makes him form unexpected alliances in the DxD world, like teaming up with Issei to take on a common enemy that neither could face alone.
In 'Twisted Fates', the plot twist is that the powers of Ichigo and a certain devil in High School DxD get merged accidentally. This leads to a new form of power that no one expected. It causes a huge shift in the power balance and makes both the allies and enemies of the characters scramble to adjust to this new situation. This fanfiction then delves into how they all cope with this unexpected development.
One of the most interesting plot twists could be the sharing of powers. For example, Naruto's ability to use chakra might combine with the unique demonic powers in Highschool DxD in unexpected ways. Maybe a character from Naruto's world gains a devil fruit - like ability from the Highschool DxD universe. Another could be a character from Highschool DxD learning how to use ninjutsu, which would completely change the power dynamics in their own world.
One interesting plot twist could be Naruto having to adapt to the unique magic system in Highschool DxD. Since Naruto has his chakra-based powers, seeing him struggle or find new ways to use his skills in a world of magic would be cool. For example, he might combine his shadow clone jutsu with some DxD magic to create a new and powerful technique.
One interesting plot could be Naruto being transported to the High School DxD world and having to adapt to the different rules about magic and devils. He might use his ninja skills in unique ways, like using his shadow clone jutsu in battles against devils or fallen angels. Another plot could involve Naruto teaching some of the DxD characters about chakra and how to use it, which would completely change the power dynamics in that world.
One interesting plot twist could be when the emotionless character from the fanfic enters the Naruto universe and their lack of emotion makes them impervious to genjutsu. Since genjutsu often plays on emotions, this gives them an unexpected advantage. Another could be a crossover where an emotionless Naruto-like character is created in a different, more dystopian universe, and has to find a way to adapt to the Naruto world's values of friendship and loyalty.
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.
One possible interesting plot could be that Naruto, with his unique ninja skills, gets transferred to High School DxD's world. He might initially struggle to adapt to the different rules and magic there. For example, he could mistake a devil's magic for some kind of new jutsu. Then, he could end up teaming with Issei and his group to fight a common enemy that threatens both the ninja world and the world of High School DxD. Maybe an ancient evil that wants to use the power of both chakras and devil magic for its own dark purposes.
One possible plot twist is that the hogyoku from Bleach somehow ends up in the hands of a character in Highschool DxD. This could lead to a character attempting to use it for their own gain, perhaps to gain ultimate power over both the devils and the angels. Another interesting plot twist is that a character from Highschool DxD gets reincarnated as a Soul Reaper in Bleach. They would have to learn the ways of the Soul Reapers while still retaining some of their previous abilities and memories. This could create some really interesting character development. A third plot twist could be that the balance between the three factions in Highschool DxD (devils, angels, and fallen angels) is disrupted by the arrival of Hollows from Bleach. The factions would have to figure out how to deal with this new threat, and it could lead to some unexpected alliances.
Well, one interesting plot twist is when the Nine - Tails in Naruto is somehow linked to a powerful devil in Highschool DxD. Imagine the chaos and new power - sharing or battling that could occur. It completely flips the script on how we see both the Naruto and Highschool DxD elements. Also, there could be a plot twist where the power - leveling system in Highschool DxD is reversed for Naruto characters, making them struggle in a new way and forcing them to adapt in unexpected ways.