Perhaps in the fanfiction, his lover was involved in something dark that Itachi couldn't tolerate. For example, she might have been collaborating with the enemies of Itachi's clan. So, to preserve the honor and safety of his clan, he made the difficult decision to kill her. It could also be that Itachi was misinformed about his lover's actions and later regretted it deeply.
One plotline could be that Naruto was mind - controlled by a powerful villain. He wakes up to find he has killed his clan and has to deal with the shock and guilt while also trying to clear his name.
The story might develop with Itachi seeking redemption in some way. He could start to perform heroic deeds to atone for what he did. Or, on the other hand, he could be hunted by those who were close to his lover. His actions could also trigger a chain of events that expose some hidden secrets in the world of the fanfiction, like secrets about his clan or the political situation in their land.
Well, I'm sure there are. Fanfiction writers often come up with wild and creative ideas. In a 'naruto killed his clan' fanfiction, it could show how Naruto would be ostracized even more than in the original story, and how he would deal with the guilt and hatred from others. It might also explore if there are any forces that could redeem him in such a dark situation.
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.
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.
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.
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.