Another might be the Byakugan. It gives a wide - range view and can see the chakra points in the body. In fanfiction, new and unique abilities of these doujutsu can be explored. For example, the author might create a situation where the Sharingan can not only copy physical techniques but also mental jutsus.
One possible doujutsu could be a time - manipulating doujutsu. It allows the user to slow down or speed up time in a small area, giving them an edge in battles. Another could be a soul - reading doujutsu, which enables the user to see the true intentions and past experiences of others by looking into their souls.
The doujutsu can drive the plot by giving characters unique powers. For example, if a character has a powerful doujutsu, it can make them a target for other characters who want to either steal the power or use it for their own purposes.
In the fanfiction, it could be that Naruto inherits the doujutsu. There might be a hidden lineage that Naruto is a part of, and when the time is right, the doujutsu awakens within him. This could be related to his Uzumaki heritage, which has many secrets yet to be fully explored. It's possible that some long - lost relative had this doujutsu and it has been passed down through the generations, finally emerging in Naruto.
If the doujutsu is very powerful, Naruto might become more confident, but also more cautious as he realizes the new responsibilities that come with such power. He would need to learn how to control it properly so as not to harm his friends or allies accidentally.
Well, it could be a doujutsu related to nature manipulation. Maybe it allows Naruto to control elements in a unique way, like combining all five basic elements simultaneously. This would give him an edge in battles as he could create complex and powerful attacks.
Another possibility is that Naruto discovers some ancient and long - forgotten ninja art that allows him to either mimic or directly acquire the three doujutsu. It could be hidden in a secret scroll or a lost temple that he stumbles upon during one of his adventures. And this art gives him the ability to have all three doujutsu.
Well, if Naruto has all doujutsu in fanfiction, it means he has access to a whole new set of powers. For example, the Rinnegan's various abilities such as the Six Paths powers. This could lead to some really interesting plot developments, like him being able to use these doujutsu to bring peace to the ninja world in a different way than in the original story. Maybe he could use the Sharingan's genjutsu capabilities to defeat enemies without having to use brute force all the time.
The doujutsu might make Fem Naruto more empathetic towards Sasuke. For example, if it allows her to see his pain, she can respond in a more understanding way, which strengthens their bond.
Well, in some fanfics, he might obtain them through some ancient ninja magic. Maybe he discovers a hidden scroll or a long - lost temple that grants him the power of all doujutsu.