Maybe he starts by observing Sakura's current chakra control. He might notice her flaws and then begin with basic chakra exercises to improve her stability.
To write a good fanfic, focus on character development. Let Sakura grow in her abilities and relationships. Show how Itachi's past affects his present actions when interacting with Sakura and Shisui. For Shisui, explore his loyalty and how that impacts the group dynamic. Also, use vivid descriptions of the Naruto world, like the Hidden Leaf Village or the battle scenes. This will make the fanfic more immersive.
Shisui lost his eye due to a complex and treacherous plot. Some powerful forces were after his unique abilities, and he was betrayed by those he trusted.
Sakura's amusement could actually make Shisui more likely to continue annoying Itachi. Since she finds it funny, Shisui might see it as a sign that his actions are acceptable and entertaining. This could potentially strain the relationship between Shisui and Itachi further if Itachi doesn't like being the target of Shisui's annoyance.
Naruto is very outgoing and loud, while Shisui seems more reserved. Naruto's energy might at first be a bit overwhelming for Shisui, but over time, Shisui would come to appreciate Naruto's positive attitude. Naruto, on the other hand, would be in awe of Shisui's skills and might try to learn from him.
In some fanfictions, Shisui's Sharingan has a different color or pattern. This is a simple but effective way to make it stand out. For example, it could be a deeper red or have an extra swirl in the pattern.
Shisui would likely be very calm and observant. He might interact with Sakura in a somewhat reserved way at first. For example, he could just give her a polite nod when they first meet on the train. Sakura, being more outgoing, would probably try to start a conversation. She might ask him about his travels or his skills. Shisui would then answer in a measured tone, sharing only what he thinks is appropriate.
First, research their characters well. Know Shisui's loyalty to the Uchiha clan and his unique abilities like Kotoamatsukami. For Naruto, his never - give - up attitude and his goal of becoming Hokage. Then, think of a unique plot. Maybe a time - travel scenario where Naruto goes back in time and meets a young Shisui. Or a situation where they have to team up to save the village from a new threat.
Sakura would likely be in awe of Itachi and Shisui's skills at first. Itachi, being the more reserved one, might be a bit distant but would gradually warm up to Sakura as he sees her determination. Shisui, on the other hand, would be more friendly and approachable. He might be the one to initiate conversations and break the ice between the three. They could have exchanges about their different ninja backgrounds.
Their relationship could start with mutual respect. Shisui might respect Sakura's determination and her growth as a ninja. Sakura, on the other hand, would be in awe of Shisui's Sharingan abilities. As they go on missions together, they start to trust each other more and more.