Often, the unique feature is the new power dynamic. Naruto having a dojutsu changes the way battles play out. For example, in many of these fanfics, he can see things others can't, like hidden traps or chakra flow, which gives him an edge in combat.
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, in some fanfictions, he might obtain it through a strange encounter. Maybe he stumbles upon an ancient relic during a mission that contains the power of the broken eye dojutsu and it somehow bonds with him.
One popular 'naruto has a dojutsu fanfic' is 'The Dojutsu's New Master'. In this fanfic, Naruto discovers a unique dojutsu that gives him new powers and a whole different perspective on the ninja world. It's really exciting as it shows Naruto using the dojutsu to overcome challenges he couldn't before.
One possibility is that he has the Tenseigan and the Ketsuryugan. The Tenseigan would grant him incredible power, such as the ability to control gravity. The Ketsuryugan could give him some sort of blood - related power, like the ability to manipulate his own or others' blood to some extent. This combination would make Naruto's character in the fanfiction very interesting, as he would have to learn to balance and use these two very different Dojutsu effectively.
It might have the ability to see through illusions that normal eyes can't. Since it's a dojutsu, even if it's broken, it could still have some enhanced visual powers. For example, it could detect the tiniest movements of an enemy, giving Naruto an edge in combat.
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.
If Naruto is given a Dojutsu in a fanfic, one of the immediate implications could be a significant boost in his combat abilities. For example, the Sharingan Dojutsu would allow him to copy his opponents' jutsu with ease. This would make him an even more formidable opponent in battles. Also, it could change his relationships with other characters. Some might be jealous of his new power, while others could see him as an even greater hope for the village. Moreover, it could open up new storylines such as Naruto exploring the origin and secrets of the Dojutsu he has been given.
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.
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.