His other friends like Shikamaru would probably approach the situation with caution. They know Naruto well, but this new development is something out of the ordinary. Shikamaru would likely think long and hard about what it means for Naruto and the group. He might try to analyze how this could affect their future missions and the balance of power in the village.
As for Sasuke, he might view Naruto in a new light. He has always been interested in power, and seeing Naruto gain such a powerful connection could make him more intrigued or even more competitive. However, he might also be concerned about the implications for the village and the ninja world as a whole.
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.
In this fanfiction, Naruto might gain new powers. Since the Kyuubi is extremely powerful, being its son could mean Naruto has an even stronger connection to the fox's chakra. He might be able to access more of the Kyuubi's abilities without the usual struggle.
If Naruto becomes the Kyuubi in the fanfiction, his character development would be a wild ride. He'd start as a regular boy with big dreams, but once he becomes the Kyuubi, he has to face a whole new set of challenges. He has to learn to control his new form and power. This might make him more serious and less carefree as he used to be. He also has to deal with how others perceive him now. Some might fear him, some might worship him. All these things would shape his character in different ways, making him more mature and perhaps a bit more jaded.
Sakura might be shocked at first. She has always known Naruto as a regular ninja. But she could also be concerned and try to find a way to help him control his vampire side. Sasuke would probably be more cautious. He'd see Naruto as a potential threat, but also might be interested in how Naruto combines his ninja and vampire powers. Kakashi, on the other hand, would be calm and start observing Naruto to understand what has happened and how it affects the village.
Sasuke would probably be a bit dismissive at first. He'd think Naruto was being childish, but deep down he might be a little curious. Sakura would likely be more understanding. She might encourage Naruto to share more about Megaman, thinking it's a harmless interest. Shikamaru, on the other hand, would just roll his eyes and say it's too troublesome for him to care about Naruto's new fandom.
His friends' reactions would be intense. Kakashi, as Naruto's teacher, would feel responsible. He would gather as much information as he could about the kidnapping. His friends from Team 7 and the other ninja in the village would band together. They would know that Naruto is strong, but also that the Kyuubi is a powerful and dangerous force. They would not rest until they found Naruto. Some might be angry at the Kyuubi, while others would be more focused on just getting Naruto back safely. They might also try to find ways to communicate with the Kyuubi, if possible, to negotiate for Naruto's release.
Sakura would probably be very angry at Kurenai. She's protective of Naruto and would demand an explanation. She might even try to heal Naruto right away if it was a physical injury.
Sakura would be furious. She's always been protective of Naruto in the original Naruto series. In the RWBY fanfiction, she would probably start her own investigation to find out who was behind the betrayal. She might even challenge the RWBY characters if she thought they were involved. Kakashi, on the other hand, would be more calm and collected. He would try to analyze the situation rationally and figure out the best way to help Naruto.
Sakura might be initially surprised but would probably be supportive. She has always cared about Naruto's happiness, so as long as he is happy with the elf, she would be okay. Kakashi, on the other hand, would likely be intrigued. He's seen a lot in his life, but an elf - ninja union would be something new. He might offer some sage advice based on his own experiences with different cultures.
Sakura would probably be a bit skeptical at first. She might worry that Naruto is getting distracted from his ninja duties. But once she sees how passionate he is, she would support him and might even help him with his training regime, using her medical knowledge to make sure he's in top physical condition for racing.