In the fanfiction, their relationship could develop in a very passionate way. Since Naruto is a very emotional and energetic character, and Fuu has her own charm. When they decide to have a child, they would be super excited about the future. However, they would also face difficulties like any couple. There might be times when Naruto's duties as a ninja conflict with his family life, and Fuu would have to be understanding. And vice versa. Through these ups and downs, their love for each other and their child would keep their relationship strong.
If we consider a more romantic relationship, it could develop slowly. Fuu could be the one to first show kindness to Dark Naruto when everyone else is afraid of him. This kindness would be a new experience for him, and he would start to open up to her. As time passes, their feelings for each other would grow deeper, and they would support each other through all the difficulties they face in the ninja world.
Naruto would initially struggle with the formalities of a political marriage. But as he spends time with Fuu, he would start to adapt. His character would become more refined in terms of handling political matters. He would learn from Fuu's grace and intelligence. Fuu would also change. She might become more assertive, as she has Naruto by her side. She would be more involved in making decisions for the greater good of both villages. Their characters would grow together, with Naruto's boldness and Fuu's tact combining to create a strong leadership duo for their joined communities.
Naruto's personality would likely become more mature. The responsibility of being in an arranged marriage might make him think more about the future. He would still keep his positive and determined side, but now he has someone else to consider. Fuu's personality could soften. She might start to open up more and show her vulnerable side to Naruto. The marriage could be a catalyst for her to become more trusting and less guarded.
Before the marriage, Naruto might first develop a friendship with Fuu. She is a spunky and independent character. Then, as Naruto also gets to know Yugito better through joint missions and diplomatic encounters between their villages, he starts to feel a connection with her as well. Fuu and Yugito, initially a bit jealous of each other's closeness to Naruto, would eventually realize that they can all be happy together. They would then start to build a relationship based on mutual respect, love, and the shared goal of making the ninja world a better place.
Their love could develop slowly. At first, they might just be comrades. But as they spend more time together, they start to notice little things about each other. For example, Naruto might notice how Fuu's eyes light up when she's excited about something, and Fuu might notice Naruto's determination in tough situations. These small observations could lead to a deeper emotional connection over time.
Their relationship would likely become more focused on the family. They would have to work together to take care of the baby, which could bring them closer. Naruto, who has always been about protecting his loved ones, would be even more determined to keep Fuu and the baby safe.
Sasuke could be a rival. He's always been competitive with Naruto, and he might see Fuu as an obstacle in Naruto's path. Also, some of the more arrogant ninja from other villages, like those who look down on Naruto's boisterous nature and Fuu's different style of fighting, could be rivals.
If Naruto and Fuu had children in a fanfiction, their kids' abilities would develop in an interesting way. Naruto's natural talent for making friends and his strong chakra would influence them. They could easily make allies and have a large reserve of chakra. Fuu's stealth and her ability to adapt quickly would also be passed on. So, the children might be able to quickly learn new jutsu and use them effectively in combat situations. They'd grow up learning from two very different but powerful ninja, which would make their abilities diverse and formidable.
The story might progress with Fuu adapting to the Leaf Village's lifestyle.
They would probably become more responsible and protective. Their relationship would be centered around taking care of their child and making sure they grow up well.