Well, one possible plot could be that Naruto is betrayed by Konoha in some extreme way. Maybe he discovers some dark secrets about the village leadership that involve using him as a tool all along. This betrayal could push him to the edge and make him turn against Konoha, leading to a situation where he kills those who he feels have wronged him.
It could be a way to explore the idea of power corrupting. Naruto has a great deal of power, and in this fanfic, it's showing what would happen if he lost his moral compass. It might also be a reaction to the traditional Naruto story's emphasis on friendship and community, flipping it on its head to show a very different, darker outcome.
The ANBU black ops could also play the role of antagonists. They are the ones who carry out the village's more secretive and sometimes morally gray missions. If they are ordered to hunt Naruto down unjustly, they would be in Naruto's way and could be the reason for his violent reaction towards Konoha.
The 'naruto returns to konoha fanfic' might focus on Naruto's relationships. For example, his relationship with Sakura could be explored further. He might come back to Konoha and realize his true feelings for her, or there could be some unresolved issues between them that need to be sorted out. Also, his bond with Kakashi and the other villagers would be re - established in a new light, as he has changed during his time away.
One possible plot could be that Naruto is pushed to the edge by the village's mistreatment of him. Maybe they wrongly accuse him of a serious crime, and in his anger and sense of betrayal, he decides to take revenge on Konoha. He could use his powerful jutsu to cause destruction to the village's infrastructure and fight against those who oppose him.
One possible plot could be that Naruto discovers some dark secrets about Konoha's leadership. For example, he might find out that they were involved in unethical experiments in the past. This discovery could make him feel betrayed first, and then lead him to take actions that Konoha sees as betrayal, like refusing to follow orders or even teaming up with an enemy of Konoha who he believes has a more just cause.
It could also be that Naruto has a misunderstanding. He might misinterpret some actions of Konoha as being malicious towards him or his friends. As a result, he decides to oppose the village. However, as the story progresses, he realizes his mistake and instead works with Konoha to resolve the issues that led to the misunderstanding in the first place.
It could be about Naruto coming back to Konoha after a long and dangerous mission. Maybe he has new skills and powers to show off.
Perhaps the council has been trying to control Naruto's power and use it for their own gain. They keep putting restrictions on him and his growth. Naruto, who values freedom and justice, realizes that as long as the council exists, the village will never be truly at peace. So he takes matters into his own hands and kills the council. This could then lead to a whole new set of challenges for Naruto, like dealing with the political fallout and trying to prove that his actions were for the greater good of the village.
Well, it could be a dark AU (alternate universe) where Naruto is pushed to the brink. Maybe he discovers some great betrayal among his friends and village. So in his rage, he decides to take revenge and starts killing everyone. But this is a very extreme and uncharacteristic concept for the original Naruto character.
In a 'Naruto Namikaze leaves Konoha' fanfic, it could be that Naruto is framed for a crime he didn't commit. The villagers turn against him, and even his friends start to doubt him. Feeling betrayed and alone, he decides to leave Konoha. As he travels, he meets other outcasts who have also been wrongly accused, and together they form a group to clear their names and seek justice.