Kasumi is likely a character created specifically for this fanfiction. She's probably a ninja with a strong connection to the 7 swordsmen. Maybe she's a new recruit or someone with a special ability that makes her relevant to the group.
The character could interact with Kasumi by initially being a bit of a mystery to her. For example, it could be a Pokemon that shows up at just the right time to help her out of a tight spot during a battle or in a dangerous situation in the wild. Then, as Kasumi tries to figure out more about this strange Pokemon, their relationship develops.
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.
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.
Yes, there are quite a few. You can start by looking on popular fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'Ranma and Kasumi love' and you'll find a variety of stories with different takes on their relationship.
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.
I really liked the fanfic 'Naruto and Fuu's Adventure'. It takes them on a journey outside the Hidden Leaf Village. They face various challenges together, and it's really exciting to see how their relationship develops throughout the story.
A great Satoshi x Kasumi fanfic often has well - developed characters. It should capture the essence of both Satoshi and Kasumi from the original Pokémon series. Their personalities, goals, and relationships with other characters should be portrayed accurately.