In a 'Naruto travel to the future fanfiction', Naruto would adapt through his strong sense of curiosity. He would be eager to explore every new thing he sees in the future. His resilience would also play a big role. If he encounters difficulties, like not understanding how a particular future - tech works, he won't give up. Instead, he'll keep trying until he figures it out. And his ninja training gives him discipline. He would use this discipline to study the new ways of life in the future, from the social norms to the technological advancements.
The marauders would probably have to adapt their way of thinking. In the future, the concepts of right and wrong, good and bad might have shifted. They'd need to understand these new perspectives to fit in.
They'd probably start by observing how things work. The Titans are smart, so they'd quickly pick up on new technology and social norms. For example, if transportation is different, they'd figure out how to use it.
Harry would rely on his basic values. His loyalty and courage would still be his strong suits. He might join a group of young wizards who are working on some noble cause in the future magic world. Through interacting with them, he'd gradually understand the new rules and customs. For example, if there are new dueling regulations, he'd learn them in the process of joining friendly duels.
He might be really surprised. Naruto is used to his own world and the fanfiction could show things he never imagined. For example, if the fanfiction has his kids achieving great things in new ways, he'd be proud yet a bit shocked at how creative fans can be.
He might be shocked at how the village has developed. In some fanfictions, the village could have advanced technology. Naruto, being from a more traditional ninja world, would likely be both amazed and a bit confused at first.
He might be shocked at first. In fanfiction, the future could be full of unexpected changes. He could be excited to see how his friends and the village have developed. Maybe he'd be a bit sad if things didn't turn out as he hoped for his loved ones.
He'd first have to get used to the new technology. If there are new magical devices, he'd need to learn how to use them. For instance, if there are advanced wands with extra functions, it would take him some time to figure them out.
The older characters such as Kakashi would be cautious. They would recognize Naruto but also be worried about the implications of someone from the future being in the present. They would want to know if his presence could change the future in a negative way. For example, they might fear that his actions could lead to the earlier awakening of a powerful enemy. As for the villains, they might see future Naruto as a threat and try to eliminate him as soon as possible. Orochimaru, for instance, would be very interested in Naruto's future powers and might try to capture him to study. And the new generation of ninja in the past would look up to future Naruto, seeing him as a symbol of what they could become.
Some characters might be shocked. For example, Naruto himself would probably be really excited to see how his world is imagined in the future. He'd be happy to see that his story has inspired so many different ideas. Sasuke, on the other hand, might be a bit more skeptical. He'd analyze the fanfiction carefully, looking for any inaccuracies or misinterpretations of his character or the ninja world's values.
He would likely be very curious. Naruto has always been eager to learn and explore new things, so seeing future fanfiction would be like opening a door to a new world of possibilities for him.