A great plot might involve a character who has the Fourth Dojutsu but has to keep it a secret from everyone. As they struggle with this burden, they start to realize that there are dark forces that are aware of their power and are trying to manipulate them. This creates a lot of internal and external conflict for the character.
It could be a descendant of an unknown clan. This character might have been living in obscurity until they discover their latent Fourth Dojutsu abilities. They then enter the world of shinobi and start making a name for themselves.
In some fanfictions, Naruto might obtain all dojutsu through some kind of ancient inheritance. Maybe he discovers a long - lost scroll or a hidden temple that bestows upon him these powerful eye techniques.
Well, one way could be through some super - rare and powerful jutsu that transfers the dojutsu abilities to him. Maybe a forbidden jutsu that was long forgotten but he stumbles upon it somehow.
Well, it could make him an even more powerful ninja. The Dojutsu might give him new abilities like enhanced perception, the ability to see chakra more clearly, or even some kind of special attack. For example, if it's a Dojutsu similar to the Sharingan, he could potentially copy jutsu more easily.
He could get a Dojutsu that allows him to manipulate time. This would be a very powerful ability as he could slow down or speed up time during battles. For instance, he could slow down time to dodge an enemy's attack and then speed it up to counterattack.
One interesting plot could be Naruto mastering a new and extremely powerful genjutsu that even the strongest shinobi can't break. He might use it to defeat a great enemy that was thought to be invincible. Another could be Naruto using his genjutsu god - like powers to enter the minds of his friends and heal their inner traumas.
In Naruto reincarnation of Kaguya fanfiction, there could be a plot where Naruto discovers that he has the ability to open new dimensions like Kaguya did. This would give him an edge in battles but also attract unwanted attention from other powerful forces. Also, the story could revolve around Naruto trying to understand Kaguya's true motives for creating the chakra system. By doing so, he might find a way to make the shinobi world a better place, perhaps by redistributing chakra more fairly or something similar.
Perhaps a plot where Naruto is influenced by an evil godlike entity. This entity could be from a different dimension. It whispers dark thoughts into Naruto's mind, gradually turning him against the values he once held dear. As a result, he starts to perform actions that are completely out of character for the original Naruto, like attacking innocent villages to gain more power.
There's also a plot where Madara and Naruto are the only two people left in a post - apocalyptic shinobi world. They must rely on each other to survive and in the process, they discover new aspects of themselves and their powers. This plot is full of action and also explores their emotional connection in a desolate setting.
Some fanfictions might focus on the psychological effects of the mind control jutsu. For example, if a character is under mind control for a long time and then is freed, how do they deal with the memories of what they did while controlled? It could be a very emotional and character - driven story. Maybe they struggle with guilt or fear of being controlled again.