If Naruto is turned into the Kyuubi in fanfiction, he could have enhanced physical abilities like super strength, speed, and durability. He might also gain the ability to use more advanced forms of chakra, perhaps even a new type related to the Kyuubi's unique chakra nature. However, he would also face the challenge of controlling this new power. If he couldn't, he could end up causing a lot of destruction, similar to how the Kyuubi rampaged in the past.
In a fanfiction where Kyuubi turns Naruto into a futa, there would be multiple implications. Firstly, Naruto's physical form change would probably require him to adapt to new ways of moving and using his abilities. Socially, he might face acceptance issues from some characters in the Naruto universe. Story - wise, it could create a whole new arc about Naruto coming to terms with his new self and using this new form to face new threats or solve old problems in a different way. This could also lead to some interesting power - up scenarios where Naruto's new form gives him unique abilities that change the power balance in the story.
In fanfictions where this happens, the development can vary widely. One common way is that Naruto's transformation into the Kyuubi causes a rift in the ninja world. Some villages might see it as an opportunity to attack Konoha while it's dealing with this internal crisis. Meanwhile, Naruto himself is trying to regain his humanity. His friends, especially those closest to him like Kakashi and Iruka, would be determined to help him. They might have to face their own fears and prejudices towards the Kyuubi as they try to reach Naruto. There could also be a sub - plot where other jinchuriki are involved, either to help or hinder Naruto's situation.
Maybe in this fanfiction, Naruto has to hide his true nature from his friends at first. As he was once the Kyuubi, he might be afraid of being rejected. This could lead to some really tense and emotional moments when his friends start to suspect something is different about him.
Naruto's core personality might not change much. He'd still be the determined and enthusiastic ninja. However, as a girl, she might become a bit more sensitive to others' feelings. For example, she could be more empathetic towards Sakura's insecurities. Also, she might be more cautious in some situations, as society in the ninja world might have different expectations of girls. But overall, she'd still have that Naruto - like spirit of never giving up.
His relationship with Sasuke would likely be very different. Sasuke might be more suspicious of Naruto at first, seeing him as an unknown entity. But as they learn more about Naruto's new situation, they could develop a deeper bond based on Naruto's unique perspective.
Yes, in some fanfictions, Naruto is often depicted as the Kyuubi or having a very close connection to it. This can lead to really interesting and unique storylines that deviate from the original plot.
One common plotline is the Kyuubi teaching Naruto new and powerful jutsu. Since the Kyuubi has a vast amount of chakra and knowledge, it could share unique techniques with Naruto that are not part of the regular ninja training. Another plotline could be the Kyuubi's influence on Naruto's relationships. For example, some fanfictions explore how Naruto's connection with the Kyuubi affects how his friends and villagers perceive him. It can also lead to some interesting character development as Naruto has to learn to control the Kyuubi's power without being consumed by it.
In many Naruto fanfictions, Naruto might have developed some new and unique abilities that the Kyuubi has no defense against. This could make the Kyuubi, which is used to being a dominant and feared force, feel vulnerable. For example, if Naruto has the power to nullify the Kyuubi's chakra or to manipulate it in a way that goes against the Kyuubi's will, it would be a cause for fear.