If Naruto becomes a vampire in fanfiction, he might gain the power of flight. This would give him a huge advantage in battles and in getting around quickly. He could also have the ability to transform into a bat or some other small creature for stealth and infiltration purposes. His chakra control might also be enhanced by his vampire nature, allowing him to perform more complex and powerful jutsu with greater ease.
He could gain super strength, allowing him to overpower enemies more easily than before. His speed would be enhanced to a level that might make him almost impossible to catch. And he could have the power of hypnosis, which would be useful in combat and getting information from foes.
He might gain enhanced physical strength like Bane. Bane was known for his brute force, so Naruto could have a similar boost, being able to overpower his opponents more easily in hand - to - hand combat.
Maybe through some kind of special training or a unique ritual. It could be that he discovers a hidden method within the ancient scrolls of his village.
He would likely gain enhanced physical abilities. Dragons are often depicted as extremely strong and fast, so Naruto as a Dragon Sage might have superhuman strength and speed. For example, he could move at blurring speeds and deliver powerful punches and kicks that could cause massive destruction.
He might gain a more powerful form of Rasengan, like a Rasengan that can change its shape and properties according to the situation. Maybe he has better control over his Nine - Tails chakra and can use it in more creative ways without losing control.
Another possible power is the ability to control all the elements with extreme proficiency, not just the ones he already has in the original series. He could combine them in ways never seen before, creating powerful and unique jutsus that could defeat any opponent.
Some characters might inherit kitsune powers through their family lineage. It could be that their ancestors had a connection with the kitsune spirits, and this power has been passed down through generations.
They could gain new powers through scientific experiments. For instance, if a character like Orochimaru were to study the atomic nature in this fanfiction concept, he might find a way to infuse atomic properties into a ninja's body, thus granting new abilities. This could involve things like the ability to emit radiation - like chakra that can either heal or harm depending on how it's controlled.
He could gain the power of controlling water like Poseidon's kids since he has good chakra control. It would be a new addition to his skill set.
Naruto would gain super strength. He could lift extremely heavy objects with ease, like mountains or large buildings in the Naruto world. He would also have super speed, enabling him to move faster than any ninja technique. And of course, he would be able to fly, which is a completely new ability in the Naruto universe.
Naruto might gain the power of shikai and bankai. Shikai is the first release of a zanpakuto's power, and bankai is the ultimate form. Naruto, with his determination and strong will, would strive to master these forms. Shikai could give him new attacks and defenses, while bankai could make him an extremely powerful force. For example, his bankai could combine his ninjutsu skills with the zanpakuto's power in a unique and devastating way.