Well, Naruto's Sage Mode could be translated into a form that allows him to sense and manipulate spiritual energy on a large scale, like how he could sense nature energy in the Naruto world. Hinata's chakra control, which was excellent in the Naruto series, could make her very good at controlling spiritual energy in the Bleach fanfiction. Their powers would not only change in nature but also in how they are perceived and used in this new universe filled with different power systems.
Naruto's ability to use the Nine - Tails' chakra could turn into something like having a powerful spiritual beast companion in the Bleach world. Hinata's Byakugan could be enhanced to see spiritual auras more clearly and detect hidden spiritual threats. Their powers would also be influenced by the fact that they are now in a world with Shinigami, Hollows, and Quincy. They might learn new techniques from the Bleach characters and combine them with their own unique abilities.
The plot could involve Naruto and Hinata being reborn as Shinigami. Naruto might be a hot - headed but talented Shinigami, quickly rising through the ranks. Hinata could be in a different division, perhaps the 4th division due to her healing - like nature. Their relationship could develop further as they face challenges in the Soul Society. They could also encounter some Bleach villains who mistake their chakra - based powers for some new and dangerous spiritual abilities, leading to some intense battles.
One idea could be a crossover where Naruto and Hinata somehow end up in the Bleach universe. Maybe they are mistaken for powerful spirits and are recruited by the Soul Society. They could use their ninja skills in battles against Hollows. For example, Naruto's Rasengan could be a powerful attack against Hollows, and Hinata's Byakugan could help in detecting spiritual presences.
Well, Naruto's chakra could be translated into a form of spiritual energy in the Bleach universe. His ability to create shadow clones might be similar to some low - level Hollow cloning abilities. As for Sasuke, his Sharingan could be a unique type of spiritual vision. Maybe it could detect hidden spiritual pressures or weaknesses in enemies. They would have to adapt to the different power systems in Bleach, like learning about Zanpakuto and the various forms of Hollowfication and Soul Reaper powers.
His powers would likely be adjusted to fit the magical nature of the DxD world. For example, his chakra might be seen as a form of unique magic. His jutsus could be enhanced or modified by the different energies present in DxD.
One common theme is power combination. Writers often explore how Naruto's and Hinata's abilities from the Naruto universe can be combined or contrasted with the powers in the Bleach universe. For example, Naruto's chakra and Hinata's Byakugan might interact with reiatsu and zanpakuto in unique ways.
Their relationship could be more hesitant. Since they are starting anew, they might not immediately recognize the bond they had in their past lives. It could be a slow process of rediscovery.
The relationship would likely become more intimate. They'd have more time to just be with each other, sharing their thoughts and feelings without any rush. For example, they could have long conversations at night before going to sleep.
A great plot twist could be that Hinata is actually related to a powerful Soul Reaper family in the Bleach universe. This could be revealed when she starts to show an unusual connection to spiritual energy. Maybe she has an ancestor who was a Soul Reaper and left a hidden power within her bloodline that only activates when she enters the Bleach world.
She might have the ability to use the Rasengan in a new way, like infusing it with Byakugan - enhanced chakra control. This would make it more powerful and precise.
Naruto might become more in tune with the Kyuubi's power. He could access more of its chakra easily and use it more effectively in battle. For Hinata, she may gain a new sense of boldness. The training could make her less shy and more assertive in combat situations.