I'm not sure if it's popular. There are so many Naruto fanfictions out there that it's hard to tell which ones are popular and which ones aren't. It could be a niche idea that only a small group of fans are interested in.
I'm not really sure as I haven't read that specific fanfiction. But generally, in Naruto fanfictions, if Naruto is the 'fem Kyuubi's slave', it might involve some sort of power dynamic where the female version of the Kyuubi has some control over Naruto. It could be a really strange or unique take on the Naruto universe, exploring different relationships and character developments that are far from the original storyline.
One possible scenario in this fanfiction could be that Naruto's transformation into a fox gives him new abilities related to the Kyuubi's powers. He might be able to communicate with the Fem Kyuubi on a deeper level, leading to an interesting dynamic between them. For example, they could team up to protect the Hidden Leaf Village in a more efficient way, using their combined fox - like skills.
No. In the Naruto series, Naruto is the host of the Kyuubi, not its slave. Fanfics might deviate from the original concept, but in the official story, Naruto has a symbiotic relationship with the Kyuubi. He gains power from it and eventually befriends the Kyuubi spirit.
No. Naruto and Kyuubi have a complex relationship. While Kyuubi was initially sealed within Naruto, Naruto gradually gains control over Kyuubi's power and they develop a more symbiotic relationship. Fanfictions that depict Naruto as Kyuubi's slave are likely straying far from the original themes of growth and friendship in the Naruto story.
Well, one possibility is that Naruto could gain new and enhanced powers. As a kitsune, he might be able to use more advanced forms of fox - related jutsu. For example, he could have better control over illusions, like creating more complex and realistic ones. Also, his relationship with the fem Kyuubi could change. Maybe they would form a stronger bond, and the fem Kyuubi could teach him things about being a kitsune that he didn't know before. This could lead to Naruto becoming even more powerful and respected in the ninja world.
Well, one possibility is that it could explore how the fem Kyuubi's new role as Naruto's mother would change Naruto's upbringing. Maybe she would use her powerful chakra to protect Naruto in ways that Kushina couldn't. For example, she could teach Naruto some unique jutsu that are related to her own nature as the Kyuubi. Also, it could show how the relationship between Naruto and the other villagers would be different. Since the Kyuubi is now in a maternal role, perhaps the villagers would be more accepting of Naruto earlier on.
There could be a fanfiction where Fem Naruto discovers a hidden side of Fem Kyuubi. Maybe Fem Kyuubi has some memories or powers that were locked away and Fem Naruto helps her unlock them. This could set off a chain of events that not only changes the relationship between them but also has a major impact on the entire ninja world as they face new threats and opportunities together.
His relationship with his friends would be very different. His old friends might be confused and a bit scared of him at first. They were used to the normal Naruto, and now he's this Joker - like figure. With the Fem Kyuubi, his relationship would be based on mutual understanding of their unique states. The Fem Kyuubi may be one of the few who can truly understand Naruto in his new form.
Well, Kakashi would likely be very cautious. He would be concerned about the implications of Naruto being with the fem Kyuubi. He would want to make sure that Naruto was not being manipulated in any way. He might keep a close eye on their relationship and offer advice to Naruto when he thought it was necessary. As for the other Konoha 11 members, some might be more accepting. They might see it as Naruto's personal choice and be happy for him if they saw that the relationship was a positive one. But there would also be those who would be hesitant, especially if they thought the fem Kyuubi could pose a threat to the village in the future.