Boruto could be developed by showing his growth in responsibility. For example, in the fanfic, he could take on the task of teaching Himawari a new jutsu. This would not only show his skills but also his patience. Himawari, on the other hand, could be developed by showing her becoming more independent. Maybe she decides to go on a small mission on her own to prove herself to Boruto.
One possible scenario could be that the 5 - Tailed Jinchuriki has some sort of special power that draws both Itachi and Karin. Maybe Itachi is initially interested in the Jinchuriki for strategic reasons related to his Akatsuki duties, while Karin is intrigued by the unique chakra of the Jinchuriki. As the story unfolds, they all find themselves in a complex web of relationships and power struggles. Itachi might be conflicted between his loyalty to the Akatsuki and his growing feelings towards the Jinchuriki and Karin. Karin, on the other hand, could be using her own abilities to try and get closer to both of them for her own survival and perhaps a bit of romance.
The 'naruto jinchuriki of the world eater fanfiction' might center around the Jinchuriki's journey. Maybe they have to face challenges that come with being associated with a 'world eater'. This could involve battles against other powerful forces in the Naruto universe who either fear or want to use the power of the 'world eater' within the Jinchuriki. It could also delve into the Jinchuriki's relationships with other characters, like how Naruto's friends might react to this new and dangerous situation.
One great idea for a Boruto and Himawari fanfic is a story where they go on a journey outside the village. They might encounter new types of ninjas or strange creatures. Himawari could be the one to sense danger with her Byakugan first, and Boruto would be ready to fight. It would show their growth as ninjas and also their bond as siblings.
Well, not having read the 'naruto jinchuriki of the world eater fanfiction', it's all speculation. The Jinchuriki is bound to be a main character. If it's set in the Naruto universe, Kakashi could also be in it. He might be in a position of trying to protect the Jinchuriki from those who would misuse the 'world eater' power. There could be a group of rogue ninjas who are after the Jinchuriki's power, and they could be major antagonists. And there may be a mysterious character who has a connection to the origin of the 'world eater' and has their own agenda regarding the Jinchuriki.
Well, it could be about Naruto somehow obtaining the power of Son Goku. Maybe there's a strange jutsu that fuses their powers. Naruto could use Son Goku's strength in battles, like having his speed and ki blasts along with his own ninja skills.
Yugito Nii is a very popular character as she is the actual 2 - Tails Jinchuriki in the Naruto series. In fanfiction, she often takes center stage, whether it's in stories about her training or her battles against powerful foes.
One great fanfic could be about Himawari and Sakurako going on a school adventure together. Maybe they are paired up for a project and during the process, they discover new things about each other. For example, they find out they both have a secret love for a certain type of music. This could lead to them bonding over it and becoming even closer friends.
There could be a fanfiction where Himawari befriends a mysterious character from another village. They go on adventures together, and through their friendship, they learn about the similarities and differences between their two villages, which in turn helps to strengthen the bonds between the two.