Naruto could be entertained. Since he loves a good fight, seeing all the made - up battles in the fanfic might be exciting for him. He'd be like a kid in a candy store, looking at all the different and wild battles that the fanfic creators have dreamed up. However, he might also be a bit critical. Given his own experiences in combat, he would notice if the battles in the fanfic don't make sense in terms of strategy or power balance. For example, if a character is made to win a fight in a way that completely defies the laws of power and skill that Naruto knows, he might shake his head and think it's a bit silly.
Naruto may also feel a sense of wonder. The fanfic world is so different from his own, yet it still involves battles and characters with powers. He could be curious about how the fanfic writers come up with these ideas. He might wonder if there are other worlds out there where these strange battles could actually happen. And if he meets the fanfic writers, he would probably ask them a million questions about why they made certain decisions in their stories, like why they made a certain character so powerful or why they paired up two unlikely characters for a fight.
He would probably be shocked. The fanfic might have some very different takes on combat and characters that he's not used to.
He might be intrigued.
He might be surprised. Fanfics can be full of wild ideas that he never thought of, like strange pairings or new jutsu concepts.
He might be shocked. The fanfiction could show his friends or himself in situations that are completely different from what he knows. For instance, if it shows him losing to a minor villain, it would be very unexpected for him.
Naruto might react with a sense of responsibility. If he saw a future where Konoha was in danger, he would feel it was his duty to do something about it. He could start by gathering information from the future vision, like the weaknesses of the enemy. Then, he would share this knowledge with his comrades and come up with a plan to protect the village.
Sasuke could be intrigued. If he comes across a well - written fanfic that really captures the essence of his relationship with Naruto or offers a new perspective on his goals and journey, he might get drawn into it. He might start to think about how these different ideas could fit into his own understanding of his life and the world around him. For instance, if a fanfic shows him a different path he could have taken, it might make him reflect on his choices.
Iida would probably be very vocal about any inappropriate or unethical content in the fanfiction. He has a strong sense of justice and propriety, so if there are any elements that go against his values, he would not hold back in expressing his disapproval.
Naruto, being the energetic and battle - loving guy he is, would likely be on the edge of his seat, eager to see who comes out on top in each death battle. He might be making bets with himself about the outcomes. Hinata, with her gentle nature, would be a bit more subdued. However, she would also be intrigued. She might be more concerned about the safety of the fighters, even though it's just a fanfiction battle. And when a fight gets really intense, she might clutch Naruto's arm without realizing it, while Naruto is too engrossed in the action to notice at first.
Sakura would be devastated. She has known Naruto for a long time and has seen him grow from a loud - mouthed kid to a great ninja. His death would make her question everything. She might become more withdrawn and serious. Hinata would be heartbroken. She had deep feelings for Naruto. She might even lose her will to fight for a while.
Ryuk would probably just be amused. He is a Shinigami who has seen a lot in his existence. Fanfiction is just another strange human creation to him. He might chuckle at some of the more outlandish ideas in the fanfictions, like a character having superpowers beyond the Death Note.
They may find it funny. There are often humorous fanfictions that could make them laugh.