In 'The Switch of Fates' fanfiction, Naruto and Hinata's roles are sort of switched. Hinata is the one who has to go on a big adventure to save the village while Naruto is the one supporting her from the sidelines at first. It flips the typical narrative and creates a whole new set of interesting situations and character developments.
One interesting plot twist could be that Hinata loses her memory. Naruto has to work hard to make her fall in love with him all over again. He shows her all the things they used to do together, and slowly, she starts to remember bits and pieces. This adds a whole new layer of drama to their relationship as Naruto is desperate to get back what they had and Hinata is confused yet drawn to him.
A possible plot twist in Naruto and Hinata married fanfiction is that they find out there is a prophecy related to their union that affects the entire ninja world. Or perhaps, an old enemy resurfaces and targets Hinata because of her connection to Naruto. This forces Naruto to make difficult choices between protecting the village and saving his wife. Also, there could be a situation where Hinata's family disapproves of something Naruto does as Hokage, creating tension in their marriage.
A great plot twist could be that Sasuke suddenly loses his sharingan and has to rely on his other skills and the help of the others. Naruto might have to train Sasuke all over again, and Hinata and Sakura could be involved in finding a way to restore Sasuke's sharingan. It would change the dynamics of their relationships and how they interact with each other.
One interesting plot twist could be that Naruto discovers he has a long - lost sibling from another village. This would completely change the dynamics of his relationships and his understanding of his own family. Another could be that Sasuke turns out to be the key to a new and powerful jutsu that was sealed away long ago, forcing Naruto to team up with him in a whole new way.
One interesting plot twist could be that Naruto initially thought he was only in love with Hinata, but during a dangerous mission where Hanabi's life was on the line, he realized he had deeper feelings for her as well. Another could be that there is a prophecy that foretells of a union between the Uzumaki, Hinata, and Hanabi which would bring great power and peace to the ninja world, forcing the characters to consider this unconventional relationship.
One interesting plot twist could be that Naruto, as a girl, has to deal with different types of relationships. For example, Sasuke might view her in a whole new light, leading to a more complex love - hate dynamic. Another could be that the female Naruto uses her new - found femininity to deceive enemies. She could pretend to be a damsel in distress and then surprise them with her ninja skills. Also, the story could take a turn where the female Naruto becomes a role model for other female ninjas in the village, changing the traditional gender roles in the ninja world.
A really cool plot twist could be that the other characters in the Naruto universe have their own hidden connections to the Indra - Ashura cycle. Maybe Sasuke is not the only one with a significant connection to the past. This could lead to a whole new set of alliances and rivalries. For instance, a character like Sakura could be revealed to have a minor connection to one of the predecessors in the cycle, which would add a new layer of complexity to her character and her relationships with Naruto and Sasuke.
A plot twist could also be that Fem Naruto's chakra has an unexpected effect on Doflamingo's powers. Since Naruto's chakra is often depicted as something very special and powerful in the Naruto universe, when combined with Doflamingo's Devil Fruit abilities in the One Piece world, it could create a whole new set of abilities or problems. For instance, her chakra might nullify his power temporarily, leading to a situation where he has to rely on her for protection in a dangerous encounter.
In some fanfictions, a great plot twist could be that the drunken swordsman's drunkenness is a ruse to hide his true form or power. When in a real battle or a crucial moment, he sobers up instantly and reveals his true, extremely powerful self. This transformation catches everyone off - guard and completely changes the dynamics of the fight and the story.
One interesting plot twist could be that Percy discovers he has a long - lost sibling within the family. Maybe a half - brother or sister from a different godly encounter that his parents had in the past. This would change the family dynamics completely and add a new layer of relationships for Percy to navigate.