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.
Well, one possibility could be that they are on a mission together. Sakura's medical skills could come in handy when Itachi or Shisui get injured. And they might face a powerful enemy that requires all of their skills combined to defeat. Maybe Itachi's Sharingan and Shisui's unique abilities, along with Sakura's strength and intelligence, make for an interesting dynamic.
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, you could go for something like 'Itachi and Shisui: A Lemon - Infused Adventure'. This title gives the idea that there's something unique and perhaps a bit zesty about their relationship in the fanfiction. Another option could be 'Lemon - Hued Memories of Itachi and Shisui', which implies that the story might be filled with memories that have a certain flavor, like the sour - sweet taste of a lemon. And also, 'Itachi, Shisui and the Lemon - Scented Plot' could work, suggesting that the plot has an element related to this lemon concept.
One possible plot could be that Itachi and Shisui are on a mission in the ANBU and they cross paths with Sakura who is also on a mission related to a medical emergency in a war - torn area. They initially have some misunderstandings as Sakura is not used to the ANBU's way of doing things, but eventually they work together. Itachi and Shisui use their combat skills while Sakura uses her medical ninjutsu to save a village from a hidden enemy's attack.
One possible plotline could be that Itachi and Shisui, being the skilled Uchiha they are, take Sakura under their wing to train her in some unique jutsu. Maybe they see her potential and want to help her reach a new level of power. For example, Shisui could teach her his body - flicker technique while Itachi imparts some of his knowledge about genjutsu. This would create an interesting dynamic as Sakura tries to adapt to their different teaching styles.
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 common theme is loyalty. Given their status as Uchiha, loyalty to the clan and to each other is often explored. For example, in many fanfics, they will go to great lengths to protect one another because of their loyalty.
Another theme is sacrifice. Given their fates in the original story, fanfictions often play around with the idea of how much they are willing to sacrifice for each other and for the greater good. It could be sacrificing their own lives or their own happiness for the other.
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.