Naruto might be a bit confused at first. The future could be so different from what he knows. But then, his determination would kick in. If he saw his friends' descendants in trouble, he would feel responsible to help, just as he felt responsible for his friends in the past. He would also be interested in seeing how the relationships between different ninja villages have evolved.
In the fanfiction, different 'httyd' characters will have different reactions to future events. Hiccup, as a leader, will be vigilant. He'll try to anticipate any problems that might come with the future changes. Astrid will be his support, but also offer her own insights. She may be more focused on the practical aspects like food supplies and shelter in a changing future. The dragons, like Hookfang, may react based on their immediate senses. If they sense danger, they'll be defensive, but if it seems like an opportunity for a good hunt or exploration, they'll be more open.
In Naruto future reaction fanfiction, characters might react to various things. For example, they could react to new jutsu developed in the future. They might be amazed at the power and creativity behind it. Maybe Naruto himself would be excited to see how the next generation has advanced the art of ninjutsu.
One possible reaction is confusion. The future shown in the fanfiction could be so different from what they expect that they have trouble understanding it at first. Another reaction could be excitement. If the future seems full of great opportunities and adventures, they would be eager to experience it. And there's also a chance of disbelief. They might think that the future depicted is too far - fetched and not in line with their own beliefs about how things will unfold.
Well, Naruto might be really confused at first. RWBY has a very different world setting compared to his own ninja world. He'd probably be intrigued by the unique characters and their powers in RWBY. For example, the use of Dust in RWBY might seem really strange to him as he's used to chakra-based abilities.
He might be really surprised. Since he's used to his own real - life adventures, seeing different interpretations in fanfiction - based anime could be quite a shock. For example, if the fanfiction shows a different version of his relationship with Sasuke, he would be taken aback.
They might be shocked by the different powers. For example, RWBY characters are used to their own semblances, and seeing Naruto's jutsus like the Rasengan would be quite a surprise.
They might be quite surprised. Minato, for example, could be shocked to see how some fanfictions might depict his relationship with his students or his family. Kakashi might find some of the stories about his past quite interesting, while Obito and Rin could have various reactions depending on how they are portrayed in the fanfiction.
He might be shocked. In the fanfic, if he sees things like his friends' future achievements or the new threats that emerge, it would surely startle him. For example, if he discovers that one of his friends has a family of their own and has become a great leader in the village, he would be proud but also a bit surprised at how much has changed.
One possible plot could be that Naruto and Hinata face a new threat to the Hidden Leaf Village. They have to work together, with Hinata using her Byakugan skills to detect the enemy's movements and Naruto using his Nine - Tails chakra for powerful attacks. Along the way, they also focus on raising their family, teaching their kids the importance of ninja values.
Well, it could be that Naruto sees a future where his friends are in danger and he starts training harder in the present to prevent it. Maybe he sees a new enemy rising that he has to face later, so he tries to find ways to defeat them before they become too powerful.