A new, mysterious organization that wants to control the chakra of strong ninja could be the main antagonist. They see Inojin and Himawari as prime targets due to their unique abilities. The organization would try to capture them, which would force Inojin and Himawari to fight together and also test their relationship as they face this powerful threat.
One possible plot could be that Inojin and Himawari are paired up for a school project. At first, they bicker a lot as they have different ideas on how to approach it. But as they spend more time together, they start to understand each other better. Inojin discovers Himawari's kind heart and determination, while Himawari sees Inojin's creativity and sense of humor. Eventually, they become good friends and maybe even develop a little crush on each other.
One possible plot could be that they are paired for a school project. As they work together closely, they start to develop feelings for each other. One day, during a moment of celebration after the successful completion of the project, they share a spontaneous kiss. It could be a sweet and innocent moment that marks the start of their relationship.
As they get older, their relationship could potentially turn into a romantic one. Inojin might be attracted to Himawari's kind heart and strong spirit. Himawari, on the other hand, could be drawn to Inojin's creativity and determination. However, this would be a slow - developing relationship, as they would first focus on their ninja careers and protecting the village. For example, they might go on missions together and gradually realize their feelings during those dangerous and exciting times.
It could be described as a gentle, hesitant kiss. Himawari might be blushing furiously as Inojin leans in slowly, their lips barely touching at first, like a soft caress. It's a moment filled with nervousness and the newness of young love.
Maybe they enter a Ninja arts competition. Himawari, with her unique abilities, and Inojin, with his artistic ninjutsu, team up. They have to overcome rival teams who underestimate them at first. As they progress in the competition, they learn more about each other's dreams and fears, and their bond grows stronger.
One way would be if they were both transported to a different dimension. In this strange new place, they have only each other to rely on. They would need to figure out how to survive and find a way back home. This shared struggle would bring out different sides of their personalities and force them to trust each other completely, thus developing their relationship in a very distinct way.
They could go on a mission to save the village. Naruto's experience, Inojin's skills and Himawari's hidden potential could combine to defeat a powerful enemy threatening the Hidden Leaf. For example, they might face a rogue ninja who has a new and dangerous jutsu. Naruto would lead the way with his Rasengan, Inojin would use his art techniques to create distractions, and Himawari could use her Byakugan to spot the enemy's weak points.
One common theme is growth. Both Himawari and Kawaki are often depicted as growing both as individuals and in their relationship. Another theme is acceptance. Since they come from different backgrounds, fanfictions usually show how they accept each other's differences.