Itachi was a complex character who was burdened with many secrets. His last wish could also be that Naruto, as Sasuke's friend, would be able to truly understand his actions and convey that understanding to Sasuke. This would help Sasuke come to terms with his brother's actions and find closure.
Another possibility for Itachi's last wish could be the restoration of the Uchiha clan's honor. He dedicated his life to protecting the village, which led to the downfall of his clan. So, perhaps in fanfiction, he wishes for a way to reconcile the village and the remaining Uchiha members, allowing them to once again be respected within Konoha.
One interesting aspect could be stories where Itachi wishes for peace in the ninja world in a more adult and complex way. For example, he might use his skills and knowledge to broker treaties between warring clans. In some fanfictions, his wish could be to see Sasuke grow into a strong and wise ninja without the burden of revenge. This often involves Itachi making sacrifices behind the scenes to ensure Sasuke's development.
If Itachi's last wish is for Sasuke's safety, it could drive the plot by leading Naruto to become even more protective of Sasuke. Naruto might go to great lengths to ensure that Sasuke doesn't fall into the wrong hands or make choices that would endanger himself.
First, understand the characters well. Know Itachi's backstory, his motives, and his relationships. For example, his loyalty to the village and his love for Sasuke. Then, think about what kind of wish he might have as an adult. It could be something related to atoning for his past sins or protecting those he loves. Start with a strong opening that sets the mood and the premise of the story. Maybe start with Itachi in a moment of reflection.
Naruto might give Itachi some traditional Konoha food as a gift. Since Itachi has been away from the village for a long time, he might miss the taste of home.
The duck could symbolize peace or friendship. Maybe Naruto gives it to Itachi as a sign of truce or new - found understanding between them.
One possible outcome is that Naruto, being in Itachi's place, might have a very different approach to dealing with the Uchiha clan situation. Naruto is known for his strong belief in redemption and friendship. He could have tried to reason with the Uchiha clan instead of the events that Itachi had to go through. This might have led to a different relationship between the Uchiha and the village.
Well, Naruto might be shocked at first. He'd probably notice the resemblance to Itachi right away. And then he'd start thinking about his own relationship with Itachi.
One possibility is that Itachi finds Naruto in a vulnerable state and decides to take him in as a pet. Naruto might initially resist but then come to understand Itachi's motives. It could be a story of Naruto learning from Itachi's skills and wisdom while being in this unique 'pet' relationship.
He might wish for the end of all hatred in the ninja world. This would mean no more wars and grudges among the villages. Everyone could focus on building a better future together.
In a 'Naruto marries Itachi' fanfiction, the plot might start with an alternate reality where Itachi never joined the Akatsuki. He and Naruto meet during their training days and form a strong bond. As they grow older, they realize their feelings are more than just friendship. They have to overcome the differences in their clans and the expectations of the village. Their marriage could then be a symbol of unity, and they might work together to face new threats to the shinobi world, all while dealing with the challenges of their relationship in a world that doesn't always accept their love.