In many fanfictions, the scenario of Naruto and Itachi killing the Uchiha clan is a very interesting but also controversial topic. One aspect could be the change in Naruto's character. Usually, Naruto stands for justice and protecting others. If he were involved in such a massacre, it would be a huge deviation from his original character. Maybe in the fanfiction, there could be some extreme situations that force him to do so, like being mind - controlled or having some false information.
In some fanfictions, a possible motivation for Naruto could be to prevent a greater evil. Maybe he was tricked into believing that the Uchiha clan was about to start a war that would destroy the entire ninja world. So, he thought that by taking part in killing the clan, he could save more lives in the long run.
One possible motive could be mind control. Maybe an enemy used a powerful genjutsu on Naruto, forcing him to commit this heinous act against the Uchiha clan.
Well, in some fanfictions, Naruto might start by finding suitable partners within the village. Since he is the last of his clan, he could look for women who are willing to carry on the Uzumaki bloodline. He may also use his influence as a hero to encourage others to support his clan - revival efforts, like getting the village to provide resources for the new Uzumaki generation.
One possible plotline could be that Naruto is forced into a situation where he has to kill Itachi to protect the Hidden Leaf. Maybe Itachi is being controlled by some dark force and Naruto, with great reluctance, has to end his life to save the village and his friends.
In this fanfiction, Naruto could reject his clan because of the dark secrets or past actions of the clan. He is a character who values justice and friendship. If the clan has a history of wrongdoings that he discovers, he may not want to be associated with it. Also, Naruto has his own dreams and goals that might not fit within the framework of the clan. He has always been a bit of a rebel, and rejecting the clan could be his way of standing up for what he believes in.
One possible reason could be to seek greater power and training opportunities elsewhere. Maybe he feels restricted within his clan in terms of the type of jutsu he can learn or the level of training he can receive. So, he decides to leave to explore different ninja arts and grow stronger on his own terms.
Yes, there are likely such fanfictions. Many fanfiction writers like to explore the idea of Itachi coming back to life with his memories intact. This allows for interesting character interactions, especially with Naruto. Itachi could use his wisdom and skills once again, and his relationship with Naruto could further develop in new and unexpected ways.
First of all, Naruto would have to establish the clan's home base. In the fanfiction, it could be a hidden village within the existing Hidden Leaf Village or a secluded area outside. He would also need to decide on the clan's hierarchy. Who would be the leaders, the elders, and the regular members? Additionally, he would need to pass on his knowledge and skills to the new clan members, perhaps by creating a special training regime.
He could start by gathering like - minded individuals. Maybe those who share his ideals of hard work and perseverance, like some of the underdogs he befriended throughout his life in the original Naruto story.