Well, in a fanfiction where Naruto fuses with Juubi, he would obtain an overwhelming amount of chakra. This would mean that he could perform jutsu without worrying about running out of chakra easily. His body would also be enhanced, maybe even to the point where he could survive attacks that would normally be fatal. Naruto's Sharingan (if he has it in the fanfiction) or his other natural abilities like his Sage Mode could combine with the Juubi's power in unique ways. For example, his Sage Mode could be amplified to cover a much larger area, and his sensory abilities could reach across the entire ninja world.
If Naruto fuses with Juubi in fanfiction, he would become a being of almost god - like status. The Juubi's power is so vast that it could transform Naruto's entire combat style. He might gain the ability to manipulate reality on a small scale, or have the power to instantly destroy large areas. Also, his connection to the tailed beasts would likely change, perhaps becoming more of a master - like figure to them rather than an ally. This fusion would also probably have a huge impact on the political situation in the Naruto world as other villages would be both in awe and fear of his new power.
In such a fanfiction scenario, Naruto would likely gain an incredible amount of power. The Juubi is an extremely powerful entity in the Naruto universe. If Naruto fuses with it, he might be able to access new levels of chakra and abilities. He could potentially have enhanced physical strength, speed, and the ability to use more powerful jutsu. His already strong willpower might be further amplified, allowing him to face even the toughest opponents with ease.
In fanfiction, if Naruto fuses with Haku, it could result in a really unique and powerful being. Naruto's exuberant and positive energy combined with Haku's stealth and ice - based skills would make for an interesting combination. They might be able to use Haku's ice mirrors in new and unexpected ways, like Naruto could add his own chakra - enhanced speed and strength to attacks within the mirrors. Also, Naruto's willpower might influence the fused entity to have a stronger sense of justice and determination, which could change the way Haku's skills are used for the greater good.
In a fanfiction where Naruto fuses with Kid Buu, it could result in a very powerful and unpredictable being. Naruto's positive energy and strong will might conflict with Kid Buu's chaotic and destructive nature at first. But perhaps over time, Naruto could influence the fused form to use its power for good. For example, the fused being might have Naruto's skills like the Rasengan combined with Kid Buu's ability to regenerate and his raw power. It could also lead to some really interesting battles against other powerful characters in the Naruto and Dragon Ball universes combined.
His personality might become more assertive. The power of the Juubi could make Naruto more confident in his actions and decisions. He may be less hesitant to use force when necessary.
The 'Naruto Reincarnation of Juubi' fanfiction would likely bring about a significant shift in Naruto's relationships. His friends might be both in awe and a little bit scared of him at first. Sasuke could see this as a new level of power to compete with or cooperate with, depending on how the story unfolds. Also, Naruto would have to learn to control the dark side of the Juubi's power, which could be a major part of the story's internal conflict.
In fanfiction, if Naruto had the Juubi, his chakra levels would skyrocket. This would give him the ability to use powerful jutsu without much strain. His physical strength would also increase, allowing him to engage in combat more effectively. He could potentially use the Juubi's power to create new jutsu or even transform into a more powerful form. However, this power would also attract unwanted attention from other powerful entities in the Naruto world. Enemies who previously didn't consider Naruto a threat would now see him as a major danger, and Naruto would have to be constantly on guard. Moreover, his friends might worry about him being consumed by the Juubi's power, leading to some interesting character - development moments as Naruto tries to assure them that he can handle it.
Well, he would probably become extremely powerful. His already impressive chakra reserves would be multiplied many times over with the Juubi's power. He might gain new and unique jutsu that are a combination of his own and the Juubi's abilities.
If Naruto merged with the Juubi in fanfiction, it could completely change the Naruto universe. His physical strength would skyrocket. Imagine him being able to withstand attacks that would normally obliterate a normal ninja. His Sage Mode and other forms might be enhanced to a level that we can't even imagine. And he might develop a new form that combines his own features with those of the Juubi, making him look both like himself and the fearsome beast.
If Naruto is trained by Juubi in fanfiction, he could potentially unlock new forms of his power. The Juubi's energy and knowledge might allow Naruto to understand the nature of chakra in a more profound way. He might also develop a different fighting style that combines his own skills with the power of the Juubi, making him a more versatile and unpredictable fighter.
If Naruto becomes the Juubi in fanfiction, he would likely gain an incredible amount of power. He might be able to reshape the ninja world. His physical abilities would be off the charts, with strength, speed, and durability far beyond what he had before. His chakra reserves would be limitless, allowing him to perform extremely powerful jutsus without tiring easily. Also, his new form could potentially change the balance of power among the ninja villages, making Konoha the most dominant force. And he could use this power to protect his friends and the entire ninja world from any threat.
If Naruto was the Juubi in the fanfic, there would be a lot of changes. First, his physical abilities would be off the charts. He could probably move at incredible speeds and have superhuman strength. His chakra reserves would be massive, which means he could perform powerful jutsu without getting tired easily. Also, the other characters in the story would probably be in awe or fear of him. His friends might try to help him control this new power, while his enemies would be even more determined to defeat him. It could also change the political situation in the ninja world, as having such a powerful being among them would disrupt the balance of power.