A possible plot could be that Dark Naruto's Eternal Mangekyou Sharingan has a special power that can merge the minds of people. He uses this to merge with the good Naruto inside him. Through this merge, he battles his inner demons and slowly transforms back to his normal self while also gaining the combined strength of both his dark and light sides.
One idea could be exploring how Itachi uses his Eternal Mangekyou Sharingan to change the past. Maybe he goes back in time to prevent the Uchiha massacre and has to deal with the consequences of altering such a major event in the ninja world.
One idea could be exploring a different origin for the Mangekyou Sharingan. For example, what if it was related to an ancient Uchiha pact with a hidden spirit? Another could be a story where a non - Uchiha character somehow gains the ability to use the Mangekyou Sharingan and has to deal with the consequences. Or perhaps a fanfiction where the Mangekyou Sharingan has additional powers that are not shown in the original Naruto series, like the ability to time - travel.
A possible plot is that Naruto gets the Mangekyou Sharingan in a fight against a powerful enemy. With this new ability, he is able to see the enemy's weaknesses more clearly. He could use the unique abilities of the Mangekyou Sharingan, like Tsukuyomi or Amaterasu, in his own unique way, since he is not an Uchiha. For example, he might combine it with his Rasengan. This would lead to new and exciting battles and also a journey of self - discovery as he tries to understand this alien power within him.
One idea could be a story where the protagonist discovers a new and unique power within the Mangekyou Sharingan that has been lost for generations. This power could give them an edge in battles against powerful foes like the Akatsuki. Another plot could revolve around a character who has to overcome the dark side effects of using the Mangekyou Sharingan, such as losing their sight at a faster rate. They could search for a way to counter this while still using the power to protect their village.
In this fanfiction, Naruto getting the eternal mangekyou sharingan might lead to him exploring his family's past more deeply. Since the sharingan has ties to the Uchiha clan, Naruto could discover some long - lost secrets about his own family's connection to the Uchiha. This could open up a whole new plotline where he uncovers hidden villages or techniques related to his family's history.
The Eternal Mangekyou Sharingan is a very powerful and significant element in Naruto fanfiction. It represents a high - level evolution of the Sharingan. In fanfictions, it often gives the characters who possess it extraordinary abilities, like enhanced visual powers, the ability to use unique and powerful jutsus.
One idea could be a story where the main character, who has the Eternal Sharingan, has to face a new and powerful enemy that can manipulate time. With the power of the Eternal Sharingan, the character has to find a way to break the enemy's time - based attacks and defenses. Another plot could revolve around a character with the Eternal Sharingan trying to uncover long - lost secrets of the Uchiha clan that are hidden deep within the Sharingan's powers. Maybe there are ancient jutsu or prophecies that only the Eternal Sharingan can unlock.
In the fanfic, Naruto having the Eternal Mangekyou Sharingan could lead to a change in his relationships. His friends might be both in awe and a bit worried about this new power he has. Sasuke, being an Uchiha, could have a complex reaction. Maybe they would train together to better understand and control this power. Naruto could also use it to try and bridge the gap between the Uchiha and the rest of the village even more, as he now has a part of the Uchiha heritage in a very powerful way.
One possible plot could be that Naruto gains the Eternal Mangekyou Sharingan through some sort of unexpected and mysterious event. Maybe it's a result of a powerful jutsu gone wrong that fuses his own chakra system with that of a Sharingan - user. This new power could initially be difficult for Naruto to control, leading to him having to isolate himself to figure it out. As he masters it, he could use it in unique ways, like combining the Sharingan's abilities with his own Rasengan techniques, creating entirely new and powerful attacks.
The plot could involve some sort of time - travel or alternate dimension scenario. Naruto could be sent to a parallel world where the Uchiha clan was never massacred. There, he befriends the Uchiha and learns their ways. Eventually, he earns the right to receive the Eternal Mangekyou Sharingan through his deeds and his strong bond with the clan. With this new power, he has to find a way to return to his own world and use it to protect his friends and village from a new, greater threat.