It could be that Shisui has been acting secretively lately. Itachi, being observant, and Sakura, who is also perceptive in her own way, notice this. They glare at him because they suspect he might be involved in something that could put the village at risk. Maybe he has been meeting with some suspicious characters. Itachi and Sakura's glares are a way of showing that they are on to him and that he should come clean about what he's been doing. As the story unfolds, Shisui might reveal that he was actually trying to protect the village in his own way, but his methods were misunderstood by Itachi and Sakura, leading to a lot of drama and tension in the fanfiction.
Itachi's personality is one of self - sacrifice and loyalty. If he is glaring at Shisui, it could be because he believes Shisui is straying from the path of loyalty to the clan or the village. His glare would be a cold and serious one, making Shisui aware of the gravity of the situation. Sakura, who has grown from a love - struck girl to a strong - willed kunoichi, would bring her determination to the table. Her glare might be accompanied by some verbal challenges, as she is not afraid to speak her mind. The combination of Itachi's silent but powerful glare and Sakura's more vocal and emotional one would create a very tense atmosphere around Shisui.
There are quite a few good writers out there. One way to find them is to search for fanfiction communities dedicated to Naruto (since these characters are from Naruto). In these communities, people often recommend their favorite writers. Some writers are known for their in - depth characterizations of Itachi, Sakura and Shisui. They make the characters feel real and add new dimensions to their relationships. You might also want to follow some fanfiction blogs on Tumblr that often share and promote great fanfictions about these characters.
One possible fanfiction could be about Sakura joining an Anbu team that has Itachi and Shisui. Maybe Sakura is a new recruit and she has to learn from the two experienced shinobi. Itachi could be the calm and collected leader, while Shisui is the more easy - going one who helps Sakura adjust to the harsh Anbu lifestyle.
A common theme is time - travel. For instance, Sakura might travel back in time and meet a younger Itachi and Shisui. This allows for interesting plot developments as she tries to change the future or just understand their past better. Also, the theme of redemption can be found. Maybe Itachi or Shisui have made some mistakes in their past and Sakura helps them find redemption through their interactions with her.
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.
One idea could be a story where Sakura, as a skilled medic, is tasked with treating Itachi and Shisui during a difficult mission. She discovers their complex pasts and bonds with them over time, leading to new alliances and friendships.
Well, I know that many fanfiction stories often explore unique relationships between these characters. For example, there could be a story where Sakura has to team up with Itachi and Shisui to face a powerful enemy. In these fanfictions, the authors might give Sakura new powers or abilities to make the story more interesting. Another common theme could be a love triangle between the three, which can lead to some really intense and emotional storylines.
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.
She could develop a more strategic mind. Shisui and Itachi are known for their intelligence in battle. Sakura would learn from them how to analyze situations better, plan ahead, and anticipate her opponents' moves. This would make her a more well - rounded ninja rather than just relying on her brute strength.