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.
First, start with a basic oval shape. Then, add the iris and pupil. Next, sketch the eyelashes and eyebrows. Finally, add shading and highlights for depth.
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 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.
First, start with the basic shape. Sketch an oval and then divide it into sections to define the iris and pupil. Pay attention to light and shadow for a realistic effect.
First, do your research on the Naruto universe, especially about the Sharingan. Know its powers, limitations, and the significance in the Uchiha clan. Then, create an interesting character. It could be someone new who gets the Sharingan or an existing character with a new take on their relationship with the Sharingan. For example, if you choose Naruto to have a Sharingan - like ability, how would that change his character and his relationships with others like Sasuke?
The story might progress as Naruto struggles to control the Sharingan at first. He may have some internal conflict as he tries to incorporate this new power into his existing set of skills. As he gets better at using it, he could start to change the power structure in the ninja world. His relationships with his friends and allies could also be affected. For instance, Sakura might be more worried about him as the Sharingan could put a strain on his body. Naruto could also use the Sharingan to uncover secrets about his parents or the history of the ninja clans that were previously unknown.