A possible plot could be about a villain who has a Mangekyo Sharingan with an ability that can create illusions so powerful that they can affect the physical world. The hero has to figure out a way to break through these illusions, and in the process, discovers a long - lost connection between their own clan and the origin of the villain's Mangekyo Sharingan.
Another plot could revolve around a character who has the Mangekyo Sharingan but is trying to hide it from both their allies and enemies. They fear the power it holds and the attention it might draw. As the story progresses, they are forced to use it in a crucial battle, and their friends then have to deal with the revelation and the potential danger it brings to the group.
One interesting plot idea could be a character from the Naruto world obtaining the Mangekyo Sharingan through some strange and unforeseen event. For example, Naruto himself could be exposed to a powerful Uchiha - related jutsu that accidentally gives him the Mangekyo Sharingan. This would completely change his power dynamic and how he approaches battles. He could then have to learn how to control this new power while still maintaining his own ninja way.
It could be an original character. Maybe a young ninja from a small, forgotten clan who discovers they have the Mangekyo Sharingan. This character would have to learn about their power, its limits, and how to use it in a world full of powerful shinobi.
Another concept is the character development. The presence of the Eternal Mangekyo Sharingan often brings a deeper level of conflict and growth for the characters. They might have to struggle with the power it bestows, such as the risk of going blind or the moral implications of using its more sinister abilities.
A cool plot idea might be a Sharingan warrior from a different dimension coming into the main Naruto universe. This warrior has a unique way of using the Sharingan that no one in the main universe has seen before. They could either become an ally or a formidable enemy, depending on their motives. Their presence could disrupt the existing power balance and force the characters in the Naruto world to adapt and find new ways to combat this new threat or form new alliances with this strange visitor.
Another plot could revolve around a character who accidentally acquires the Rinne Sharingan and has to learn to control it while being hunted by various groups. Some might want to use the power for their own evil purposes, while others fear the unknown capabilities. This character could start as a relatively weak ninja but gradually become stronger as they master the Rinne Sharingan, forming alliances with unexpected characters along the way.
One idea could be that Naruto discovers a hidden Uchiha ancestor in his family tree. This could lead to the dormant Sharingan gene awakening in him. He then has to learn to control the Sharingan while still maintaining his own unique ninja abilities. Another plot could be that during a battle with a powerful enemy, Naruto is somehow merged with an Uchiha ninja, and as a result, he gains access to the Sharingan. He then uses it to gain new insights into his opponents' moves and strategies.
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.
One idea could be a story where the Sharingan evolves to an ultimate form that gives Naruto unique powers. For example, he might be able to use it to instantly teleport to any location he has previously visited. This would add a new dimension to his fighting abilities and his ability to save his friends quickly.
One possible plotline could be Naruto unlocking the Mangekyo Sharingan through some strange and unforeseen means, perhaps a powerful jutsu backfires and gives him this new power. Then he has to struggle with controlling it while his friends are both amazed and a bit worried about this new development in him.
Another plot idea is that Naruto gets a Sharingan in a parallel universe. In this universe, he has to learn how to control it quickly while also dealing with the different political situations. Since the Sharingan is so powerful, many might try to either use Naruto or take the Sharingan from him, creating a lot of action - packed and suspenseful situations.