In some fanfictions, it could be due to a special jutsu gone wrong. Maybe a jutsu that Kakashi was using to transfer some of his chakra to Naruto for a mission accidentally transferred his Sharingan power as well.
One possible reason could be that Kakashi is in a life - threatening situation and realizes that Naruto is the best candidate to inherit his Sharingan. He knows Naruto's potential and his desire to protect the village. Another reason could be that Kakashi wants to see how Naruto would use the Sharingan in combination with his own unique abilities. He's curious about the new powers and techniques that Naruto could create with it. Also, it could be a way for Kakashi to show his complete trust in Naruto, as the Sharingan is a very precious and powerful gift.
One great fanfiction could be about Kakashi using his Sharingan to train Naruto in a special jutsu. Maybe he shows Naruto how to better perceive an opponent's moves by using the Sharingan's ability to analyze. This could lead to Naruto developing a new and powerful technique that combines his own chakra control with the insights from the Sharingan.
Well, Kakashi might constantly train Naruto privately to make him stronger. He would keep a close eye on Naruto during dangerous missions, ready to jump in and save him at any moment. For example, if Naruto is about to be attacked by a powerful enemy, Kakashi would use his Sharingan to quickly assess the situation and block the attack.
Having Kakashi's Sharingan would force Naruto to mature faster in terms of his strategic thinking. He can't just rely on his Nine - Tails chakra and his normal combat style. The Sharingan would expose him to a whole new level of ninja tactics. This would also impact his relationships. His friends might look at him differently, and he might feel a bit isolated as he tries to master this new power. Over time, though, it could make him a more well - rounded and respected leader in the shinobi world as he combines the Sharingan's abilities with his own strong will and values.
Well, Naruto already has his own powerful abilities like the Nine - Tails chakra. But getting Kakashi's Sharingan could enhance his perception skills. He'd be able to see attacks better and react faster. Maybe he could even copy some jutsu more easily, just like Kakashi used the Sharingan to copy many jutsu in the original series.
The fanfiction might show Kakashi growing in terms of his understanding of the Sharingan's true nature. As he delves deeper into the abilities of the eternal Mangekyou Sharingan, he could gain a broader perspective on the Uchiha and their powers, which in turn enriches his own character development. He may start to see things from an Uchiha - like point of view, which was previously foreign to him. Also, the new power might attract new enemies or allies, and through these interactions, Kakashi will have to adapt and grow. For example, if new enemies target him because of his powerful Sharingan, he'll need to find ways to outwit them and protect those he cares about. This will surely contribute to his character growth.
One interesting fanfic could be where Kakashi uses his Sharingan in a unique way to train Naruto. Maybe he shows Naruto how to better analyze his opponents' moves just by using the Sharingan's ability to copy and predict. For example, Kakashi could create a special training ground where Naruto has to face multiple clones of himself that mimic the fighting styles of different enemies. And the Sharingan plays a crucial role in Naruto understanding the patterns of these clones.
The consequences could be far - reaching in the fanfiction. Naruto's relationship with Kakashi might change. There could be a deeper sense of respect and a new kind of bond formed because of this transfer. In terms of power, Naruto could unlock new jutsus or abilities that are related to the Sharingan. He might be able to combine his existing Rasengan techniques with the Sharingan - enhanced perception. This could make him an even more formidable opponent. However, it could also put a strain on his body. The Sharingan is known to consume a lot of chakra, and Naruto's body might need to adapt to this new power drain. If he overuses it, it could lead to exhaustion or even long - term damage.
One great 'Naruto Kakashi's Sharingan' fanfic could be 'The Legacy of the Sharingan'. It delves deep into how Kakashi's Sharingan not only affects his combat abilities but also his relationships with other characters like Naruto. It might show how he passes on some of his knowledge related to the Sharingan to Naruto.