In this fanfiction, it could be that Naruto discovers a dark secret about his past, such as his parents being involved in something evil. This knowledge could shatter his world view and send him into insanity. He might then go on a quest to find the truth, but his deteriorating mental state causes him to act erratically and make enemies of those who are actually trying to help him.
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, after becoming a Madara fan, starts to question the traditional values of Konoha. He might see Madara's vision of a more unified world under his rule as something appealing. This could lead to a rift between him and his friends as they struggle to understand his new perspective.
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.
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's mental instability causes him to misinterpret the Fem Kyuubi's intentions. Maybe he sees her as a threat when she's actually trying to help him. This could lead to a lot of internal conflict within Naruto and also create tension in their relationship.
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.
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.
Another is the discovery of a dark secret about his family or the village. Maybe he finds out that the village leaders had some malicious intentions towards his family all along. This realization could be too much for him to handle and make him lose his sanity.
Perhaps Naruto, as a knight, has to face off against his former ninja comrades who now see him as a threat to the ninja world. They believe his new knightly ways go against the ninja code, creating a conflict between loyalty and his new identity.
One possible plot twist could be Hermione getting tired of being overlooked in the wizarding world despite her intelligence. She might turn to the Dark Arts out of a sense of vengeance. For example, she could start using her knowledge of spells to manipulate those who have underestimated her, like some of the pure - blood supremacists. Maybe she'd form her own group of followers who are also disillusioned with the current state of the wizarding world order.