There's a really interesting one where the author gives a different perspective on the fight. It's called 'Naruto and Sasuke vs Momoshiki: An Alternate View'. It focuses more on the strategic aspects of their combat that the anime might not have fully explored.
It's appealing because we get to see more of the characters' thoughts and feelings during the fight. In the original series, there are limitations on how much of their internal monologues can be shown. Fanfictions fill that gap. For example, a fanfiction might show Naruto's doubts and how he overcomes them during the battle with Momoshiki. Also, some fanfictions might explore different relationships between Naruto, Sasuke and other characters in the context of this battle, like how their teamwork affects the fight in ways not shown in the anime or manga.
He'd probably be very intrigued. Percy has a penchant for adventure and new things, and this fanfiction would be something completely different from what he's used to.
I think young Sasuke would have a very intense reaction. He was so consumed by his hatred for Itachi at that young age. A Sasuke vs Itachi fanfiction would be like a trigger for him. He would be eager to see how the fictional fight is portrayed. If Sasuke in the fanfiction is shown as strong, it might fuel his own ego and make him strive even harder to become powerful. However, if the fanfiction shows Itachi as superior, it could enrage him. He might feel that it undermines his own goal of defeating Itachi and he might even want to find the writer to correct their 'wrong' view.
I like Naruto in these fanfics because he always stays true to his beliefs. He is constantly trying to bring Sasuke back to the village and is willing to fight for their friendship.
One of the best moments is when they have a rematch that showcases their growth. Naruto has become stronger with his new jutsu, and Sasuke has further mastered his Sharingan powers. The intense battle of ideologies during the fight is captivating.
I really liked 'A New Beginning for Momoshiki in Naruto'. This fanfiction takes an interesting turn where Momoshiki is reincarnated in a different form and has to navigate the world of Naruto from a different perspective. It's full of action and also some great character development for Momoshiki. Also, 'Momoshiki and Naruto: Unlikely Allies' is a great read as it focuses on how their powers could combine in unexpected ways.
There are fanfictions where Momoshiki and Naruto interact in unique ways. Maybe Momoshiki has some knowledge that Naruto needs, and they have to negotiate. Their power levels are compared and contrasted. Naruto's ability to use Sage Mode and his chakra reserves are pitted against Momoshiki's alien - like powers. It creates a dynamic where both characters are forced to adapt to each other's fighting styles.
Sasuke would be furious. He's always been protective of Naruto in his own way. He would immediately start looking for her, using all his skills and resources. He might even go on a rampage if he thought Naruto was in serious danger.
Naruto would probably be angry at first. He's always been a free - spirited person, and being kidnapped by Sasuke, his friend - turned - rival, would surely make him mad. He'd likely try to fight back immediately, using his ninja skills and his never - give - up attitude.