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 idea could be a story where Boruto and Himawari discover an old diary of Naruto's from his early days as a ninja. Hinata helps them understand the context and the values their father held. They then use those lessons to face a new threat in the village.
Websites like FanFiction.net and Archive of Our Own (AO3) are great places to start. They have a large collection of fanfics related to Naruto and his family.
There are many fanfics that explore the relationship between Naruto and Hinata further. Some might focus on their daily family life with Boruto and Himawari, like how they deal with Boruto's rebellious phase while still maintaining a loving family environment.
One idea could be a story where Boruto and Himawari discover an old lemon tree in the Hidden Leaf Village. Naruto and Hinata then tell them about a legend that the tree was planted by the first Hokage. The kids decide to take care of the tree and throughout the process, they learn more about their family's history and the importance of nature in their village.
One great 'Boruto and Himawari fanfic' is 'Sibling Adventures'. It shows their daily life in Konoha, with Boruto teaching Himawari some new ninja techniques in a really cute way. They also have some small adventures together around the village, like finding a lost pet. Another one is 'Himawari's Growth' which focuses on Himawari's development as a ninja under Boruto's guidance. It's really inspiring to see their bond strengthen as she learns.
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, it could be a story centered around a festival in Konoha. Naruto and Hinata are preparing for the festival, and Boruto and Himawari are super excited. But then some strange things start to happen. Mysterious ninjas appear and seem to be up to no good. Boruto and Himawari get caught up in the mystery, and with the help of Naruto and Hinata, they figure out that these ninjas are actually from a far - off land and were just lost. In the process, the family bond gets even stronger.
Perhaps in the fanfic, Boruto and Himawari are involved in a festival in the village. They enter a contest together, like a ninja skills show - off. Boruto is a bit overconfident at first, but Himawari keeps him grounded. In the end, they learn more about each other and their combined strength as siblings.