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.
One common theme is unrequited love. Sakura often has strong feelings for Sasuke, but Sasuke may be too focused on his own goals to fully reciprocate. Another theme is the power struggle. Since they are both powerful ninjas, their battles can represent a struggle for dominance or recognition within the ninja world.
He might feel anger. Since he was so set on revenge against Itachi, any portrayal that didn't match his view of himself as the victor could make him angry.
Another scenario could be that Naruto and Sasuke discover a new power within themselves during the fight against Kaguya. This new power could be related to their friendship or their connection to the Sage of Six Paths. They then use this power to finally defeat Kaguya.
Most likely Naruto and Sasuke. In the original series, they were already very powerful when they faced Kaguya, and in fanfiction, they could be even more so. Their combined strength and determination usually make them the favorites to win.
Expect their friendship/rivalry to be at the center. The fight is not just about who is stronger physically. It's about their bond. In fanfiction, the writers often play with the idea of whether they can still be friends after such an intense battle. It's a very emotional aspect.
First, make sure you're familiar with the Naruto and Sasuke relationship in the original manga or anime. This will help you better understand and appreciate the fanfiction. Second, don't be afraid to try different genres within the Naruto vs Sasuke fanfiction. It could be action - packed, angsty, or even have a touch of romance. Third, pay attention to the writing style. A clear and engaging writing style can make a huge difference in your reading experience.
One popular sakura vs sasuke fanfiction is 'The Duel of Hearts'. It explores their complex relationship through an intense sparring match where their emotions and past experiences come into play. Another one could be 'Clash of Ideals' which delves into their different outlooks on life and how that affects their interactions.
Obviously, Naruto and Sasuke are going to be the main characters. Their relationship and how it develops after their fight is likely to be the central focus of the fanfic.
In such a fanfiction, Naruto might use his new and improved Rasengan techniques that he's been secretly practicing. Sasuke, on the other hand, could unveil some new Sharingan powers. It could be a battle full of intense jutsu exchanges and emotional turmoil as they both strive to prove themselves in the Chunin Exams.