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.
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 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.
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.
They're popular because Kakashi is a very popular character. His Sharingan gives him a unique and cool look. Fanfics about it allow fans to explore more about his powers, which were not fully shown in the original series. For example, fans can create scenarios where Kakashi uses his Sharingan in ways we haven't seen before.
Yes, in some fanfictions, Naruto might end up having Sasuke's Sharingan through various creative plot devices. For example, in a story where there's a powerful jutsu gone wrong that transfers Sasuke's abilities, including his Sharingan, to Naruto. This can lead to really interesting character developments as Naruto has to learn to control and use this new power.
In a fanfic, Naruto getting Sasuke's Sharingan could be part of a plot where Sasuke sacrifices himself to save Naruto. Before dying, he gives Naruto his Sharingan. Naruto then has to deal with the new power as well as the emotional weight of carrying a part of Sasuke. He could use the Sharingan to see through illusions more easily and even gain some of Sasuke's memories related to the Sharingan's usage.
Kakashi may also get angry. Angry at the people or things that caused Naruto to get those scars. This anger could fuel his determination to make Naruto stronger, so that he can better defend himself in the future. He might then intensify Naruto's training, all while having a new - found sense of protectiveness towards Naruto.
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.
In this fanfiction scenario, Kakashi's failure might cause Sasuke to be more reckless. Sasuke, feeling let down, could go off on his own more often. Sakura, who might have relied on Kakashi to keep Sasuke in check, would then be left to try and deal with Sasuke on her own. This could put a lot of stress on their relationship. She might be more desperate to bring Sasuke back to the right path, but Sasuke could see her as being too pushy, all because of Kakashi's initial failure.