In such a fanfiction, Sarada might be in awe of Itachi. She could learn valuable ninja skills from him. Itachi might see Sarada's potential and offer her some advice on how to better control her Sharingan and improve her combat abilities.
A possible relationship could be one of mutual respect. Sarada would respect Itachi for his skills and his past sacrifices. Itachi, on the other hand, might see Sarada as a symbol of hope for the future of the Uchiha clan. They could share stories about the Uchiha, with Itachi passing on the history and traditions that Sarada might not be fully aware of. This could strengthen their bond and lead to a deeper understanding between them. In the fanfiction, they might also team up to face a common enemy, relying on each other's strengths and abilities, which would further solidify their relationship.
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.
Sasuke often appears in different story arcs of the Boruto manga, depending on the current plot and mission. Sometimes he's on a solo mission, sometimes he's involved in events related to the village.
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.
Naruto is likely to be popular too. Even though it's a Boruto x Sasuke fanfic, Naruto's relationship with both of them is so important. He could play a role in supporting them from the sidelines or even getting involved in a crucial part of the story.