One possible plot twist could be that Naruto's new form as a tailed beast gives him the ability to communicate with all the tailed beasts simultaneously. This could lead to him uniting them in a way that no one has ever seen before, and they might work together to bring about a new era of peace in the ninja world.
Perhaps in the fanfiction, Naruto becoming a tailed beast could cause a shift in the balance of power among the ninja villages. Other villages might see him as a threat and form alliances against Konoha. Naruto, in his new form, would then have to prove that he is not a danger and that his transformation can actually be beneficial for all. He could do this by using his new powers to solve problems that the ninja world has been facing for ages, like the shortage of natural resources or the lingering hatred between different clans.
Well, in this fanfiction, a really interesting plot development could be that Naruto, as a tailed beast, starts to lose his human emotions gradually. This would be a huge struggle for him and his friends. His friends would have to find a way to bring back his humanity while also dealing with the fact that Naruto now has this incredible and dangerous power. They might have to seek out ancient ninja techniques or make deals with other powerful entities to save Naruto.
One idea could be that Naruto discovers a new ancient power source that fuses with his existing chakra, gradually transforming him into an 11 - tailed beast. This new form could give him abilities beyond what we've seen in the original series, like the power to manipulate time on a small scale. Maybe he uses this new power to go back in time and prevent some of the tragedies that occurred in the Naruto world.
In this fanfiction, the plot might involve Naruto being experimented on by some dark force. This experiment causes him to transform into a tailed beast in a way that's different from his normal jinchuriki forms. As he changes, he starts to view the world from a more primal perspective. He might even break away from the Hidden Leaf Village and the story could be about his journey to regain his sanity and his place among his friends and the village.
One possibility is that Naruto would initially be confused and struggle to control his new form. He might accidentally cause destruction in the village as he tries to figure out his new powers. But with the help of his friends, like Sasuke and Sakura, he could start to learn to harness the tailed beast's abilities for good, perhaps even developing new jutsu.
One possible plot twist could be that Naruto, after learning more about Itachi's sacrifices for the village, starts to idolize him in a way that changes his own ninja path. He might adopt some of Itachi's stealthy and strategic techniques. For example, he could focus more on gathering intelligence before acting, rather than his usual head - on approach.
Maybe in this fanfiction, Naruto is exposed to a powerful dark jutsu that slowly corrupts his mind. As he becomes insane, he begins to abandon the values he once held dear. He could start using his powers for self - gain rather than for the protection of the village, like taking over control of Konoha in a tyrannical way.
One possible plot twist could be that Naruto's transformation into wrath is triggered by the loss of a dear friend. This could lead him to abandon his usual beliefs and go on a vengeful rampage against the enemy. Maybe he starts to use darker forms of his jutsu without regard for the consequences.
One possible plot twist could be that Naruto loses control over his transformation into the Nine - Tailed Fox in a completely unexpected situation. Maybe during a friendly spar with his friends, and this causes them to fear him in a new way. It would add a whole new layer of drama to their relationships.
In this fanfiction, a possible plot twist is that Naruto's transformation into a Jashinist causes a rift in the ninja world. Some villages see him as a threat and form alliances against him. However, Naruto, using his unique perspective as a former Leaf ninja turned Jashinist, tries to bridge the gap between different ninja factions. He might also discover that Jashinism has a connection to an ancient prophecy that only he can fulfill, which changes how everyone views him and his new beliefs.
One possible plot twist could be that Naruto's new fallen angel powers make him an outcast in Konoha. His friends might be afraid of him at first. For example, Sasuke could see him as a threat to his own power. Another twist could be that Naruto has to fight against a dark force that is trying to control his fallen angel powers for evil purposes. He would have to struggle to keep his good nature while having these new, potentially dangerous powers.
He could be experimented on by rogue ninja scientists. These scientists might have been researching ways to create super - powerful beings and see Naruto as the perfect test subject. They use some forbidden jutsu or strange technology to try and force the creation of an 11 - tailed form within Naruto.