Sakura might tease Naruto about it a little. She'd probably think it's a bit strange that he's interested in something so different from their own world. But she'd also be curious to know what it's all about.
Shikamaru would probably just shrug it off. He's used to Naruto's odd interests. He might say something like 'Well, that's Naruto for you. Always finding something new to get into.' But deep down, he might also be a bit intrigued by the idea of RWBY fanfiction and might even ask Naruto to tell him more about it later.
Sakura would probably tease Naruto a little bit. She might say something like 'Naruto, you're such a dork for reading that fanfiction.' But then she would also be interested in what it's about and might ask Naruto to tell her some of the cool parts.
Sasuke would likely act like he doesn't care much. But secretly, he might be a bit intrigued as to why Naruto is into such things. He might think it's a waste of time or he could see it as another way Naruto is different from him.
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.
He might be surprised. He's used to his own life and adventures, and seeing it twisted and turned in fanfiction could be unexpected.
Sakura might be a bit surprised at first. She would probably tease Naruto a little about it, but then she'd also be curious to see what's in those fanfics. She might even start reading some herself to see how the fans portray her relationship with Naruto.
Sakura might be a bit surprised at first. But she would probably be happy for Naruto as long as he is happy. She might also be curious about the elf and want to learn more about her. Sasuke would likely be more reserved in his reaction. He might not show much emotion on the surface but deep down he would be glad that Naruto has found someone. Kakashi would probably give Naruto some sage advice about making a relationship work, especially since it's with someone from a different species.
His friends' reactions would be diverse. Naruto's more hot - headed friends like Kiba might be excited about the new firepower the modern army brings. They might want to jump right into using the guns and other weapons. But Naruto's calmer friends like Neji (if he were still alive in the fanfiction) would be more cautious. They would worry about the long - term effects on the ninja world, such as the potential for mass destruction and how it would change the balance of power. And Ino might be interested in how the modern army's communication systems could be used to improve their own ninja intelligence networks.
His friends would likely be shocked and deeply concerned. Sasuke might put aside their differences and be by Naruto's side, offering his support.
Sasuke might be initially cautious. He would observe Cell carefully to assess his threat level. He could offer his Sharingan - enhanced perception to help Naruto in the fight. Sakura, she would be worried about Naruto but also ready to jump in and heal any wounds. Shikamaru might be thinking of strategies in the background, trying to come up with a way to outwit Cell using his intelligence.
Sasuke would be furious. He already has a strong sense of justice and loyalty to Naruto. He'd likely immediately start looking for Naruto, using his Sharingan to track any possible leads. He might even go against the village rules if he thought the village was involved in Naruto's kidnapping.