Sasuke might be initially surprised. He is used to the Sakura from his past, so seeing a different, more mature future Sakura could catch him off guard.
Well, Itachi might be shocked to see how much Sasuke has changed in the future. Maybe Sasuke has developed new powers or a different outlook on life. Itachi could also feel a sense of pride or regret depending on how Sasuke has turned out.
In this fanfiction, Sasuke might be shocked to see how much Sakura has changed in the future. Maybe she has become a more powerful ninja, or perhaps she has achieved great things in the medical field, which could make Sasuke view her in a whole new light.
One possible plot could be that future Sakura, with her advanced medical skills and battle experience, goes back in time and meets a younger Sasuke. She might try to prevent some of the tragedies that Sasuke later endures. For example, she could warn him about Orochimaru's true intentions, which would change the course of Sasuke's journey. This would also lead to different interactions between Sakura and Sasuke compared to the original story. Their relationship might develop in a more positive way earlier on, as Sakura from the future has a deeper understanding of Sasuke's pain and the consequences of his actions.
If we consider emotional dominance, Itachi might be more dominant at first as he has always been in control of his emotions and has a lot of secrets that could shock Sasuke. But if future Sasuke has overcome his emotional turmoil and has a clear goal in mind, he could turn the tables. In a physical or power - based sense, it could go either way depending on how the author of the fanfiction has developed their respective powers and skills in the future scenario.
Their relationship would likely become more complex. Since future Sakura has more knowledge about Sasuke, she would approach him differently. She might be more confident and less shy around him compared to her younger self. Sasuke, on the other hand, would be intrigued by this strange girl who seems to know so much about him. He might start to trust her more quickly than he did in the original story, which could lead to a deeper emotional connection between them.
One possible scenario in this fanfiction could be Jiraiya taking on the role of a mentor to young Naruto even more intensively. He might teach Naruto some unique jutsu that are not part of the original storyline. For example, he could introduce Naruto to some ancient toad - related techniques that are only known within the toad clan.
One possible plot could be that Naruto goes on a special training journey with Jiraiya again, but this time they encounter a new and powerful enemy that has a connection to Jiraiya's past. Naruto has to learn a new jutsu from Jiraiya to defeat this foe.
In this fanfiction, perhaps Jiraiya didn't actually die. He was in a hidden place recovering from a serious injury. When he meets Naruto again, Naruto is shocked but overjoyed. Jiraiya then shares his newfound knowledge and powers with Naruto, and they team up to take on a powerful organization that threatens the Hidden Leaf Village. Jiraiya could teach Naruto some advanced Sage Mode techniques that he had been working on during his absence.
Obviously, Naruto and Jiraiya are the main characters. Naruto is the young and energetic ninja with big dreams, while Jiraiya is the experienced and somewhat pervy sage who has a lot to teach Naruto.