How about a twist where Hinata was secretly trained by an unknown master all along? And this training was to prepare her for a great prophecy that involves Boruto and Himawari. When the time comes, she reveals her new and unexpected skills to save her family.
A plot twist could be that Naruto discovers he has a long - lost relative who has a connection to Boruto's and Himawari's future. This relative has a dark past and his appearance throws the family into chaos as they try to figure out his motives and how it will impact their lives.
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.
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.
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.
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.
Naruto and Hinata's relationship could grow as they face parenting challenges together. They would support each other more deeply, and their love would be even more evident to Boruto and Himawari. Boruto might start to understand his father better and respect him more as he sees how hard Naruto works for the family and the village. Himawari would continue to be the sweet, loving daughter, and her bond with Hinata would strengthen as Hinata teaches her more about being a kunoichi. And Boruto and Himawari's relationship as siblings would become closer as they go through various adventures together.
Let's say a traveling merchant brings a rare lemon that has special properties. Boruto is curious and wants to study it. Himawari tags along. Naruto and Hinata are initially worried but then support their children's inquisitiveness. The lemon could be the key to unlocking a new power or it could lead them to a new adventure outside the village, with the family having to rely on each other in unfamiliar situations.
A great plot twist could be that Hinata is actually related to a powerful Soul Reaper family in the Bleach universe. This could be revealed when she starts to show an unusual connection to spiritual energy. Maybe she has an ancestor who was a Soul Reaper and left a hidden power within her bloodline that only activates when she enters the Bleach world.
Another aspect could be the family relationships. When Naruto is in Himawari's body, he gets to experience how his family members interact with Himawari on a more personal level. He might realize things he hadn't noticed before about how his daughter is treated and how she feels. And on the other side, Himawari in Naruto's body might gain a newfound respect for her father's responsibilities and the pressure he's under all the time.
A fanfiction could explore Himawari starting to show signs of her own unique ninja abilities, and Naruto and Hinata trying to figure out the best way to help her develop them. Maybe she has an ability that neither of them has seen before, which causes some confusion and also excitement in the family.