A potential plot twist could be that Zabuza has a hidden agenda for allowing Naruto to join him. Maybe he plans to use Naruto as a pawn against the Hidden Leaf Village, which would create a huge moral dilemma for Naruto.
One potential twist could be that Percy is actually undercover for the good guys all along while pretending to join Gaea.
One possible plot twist could be that Naruto develops a much darker and more ruthless side due to Zabuza's influence. Instead of the optimistic and friendly Naruto we know, he might be more solitary and calculating in his approach to battles and relationships. For example, he could be more willing to use underhanded tactics like Zabuza's use of hidden mist jutsu to ambush opponents.
One possibility is that Naruto could learn new combat techniques from Zabuza. Zabuza was a highly skilled swordsman, and his fighting style was very different from what Naruto was used to. Naruto might adapt some of Zabuza's stealth and assassination skills, which could make him a more versatile fighter in future battles.
One possible plot twist could be that Naruto not only saves them physically but also manages to change their view on the world so much that they become allies with Konoha. For example, Naruto might show them the true meaning of friendship and loyalty, which makes them question their previous life of being mercenaries. This could lead to a whole new dynamic in the story where they use their skills for good instead of just for money or power.
One possible plot twist could be that due to Zabuza's influence, the female Naruto becomes more of an assassin - type. She might develop a different set of values compared to the original Naruto. For example, she could be more ruthless in combat and less hesitant to take lives when necessary.
A plot twist could be that Zabuza's past and his relationship with Haku are revealed to Naruto in a different way. This could lead to Naruto having a unique understanding of loyalty and sacrifice. He might then develop his own version of the 'ninja way' that combines the values of the Leaf Village with Zabuza's more self - serving but also protective nature.
One possible plot twist could be that Zabuza has a change of heart and decides to train Naruto secretly on their journey. He could see Naruto's potential and want to make him a stronger ninja, which would completely change Naruto's fighting style later on.
A plot twist could be that Medusa is actually an undercover agent sent to the Naruto world to steal secrets, but she falls in love with Naruto instead. This would create a conflict between her original mission and her new - found feelings.
A possible plot twist in this fanfiction might be that Naruto's new status as the jinchuriki of Saiken attracts a new group of enemies who are specifically after the power of the Six - Tails. Also, there could be a situation where Naruto's friends start to fear him because of Saiken's power, thinking he might lose control. And perhaps there is a hidden prophecy that only Naruto as the jinchuriki of Saiken can fulfill, which leads to a whole new adventure and set of challenges for him.
A really interesting plot twist could be that Naruto is not the only 'daughter' of Artemis in the Naruto world. There could be other characters who also have a connection to Artemis, and they initially see Naruto as a threat. This could lead to a lot of internal conflict within the group related to Artemis. Also, what if Artemis has some sort of dark secret or past event that affects Naruto's role in the story? For example, Artemis might have made a deal with an evil force in the past that now comes back to haunt Naruto. And perhaps Naruto discovers that her connection to Artemis is not as straightforward as she thought, and there are hidden motives behind her being brought into the world as Artemis' daughter.