They might first be shocked by the new environment. But then, they would start using their skills. Captain America could use his leadership skills to gather information. Iron Man would start analyzing the new technologies right away.
In fanfiction, when the Avengers go to the future, their adjustment would be a complex process. They are used to their own time's rules and ways of life. At first, the strange architecture, different social norms and advanced or deteriorated technology would be overwhelming. However, they are heroes. Iron Man, with his genius intellect, would start reverse - engineering the future tech to understand it better. Captain America would try to find the good in the new society and lead the team to integrate. The Hulk might be a bit of a wild card, but he could also be a powerful asset if they can control his rage. They would gradually adapt by learning from their mistakes, observing the locals, and making use of their own unique abilities in new ways.
There would be a mix of reactions. Tony Stark, being the confident and curious type, would probably start asking a million questions right away. He'd want to know about new inventions, future threats, and how he can improve things in the present. Meanwhile, Hawkeye might be more cautious. He'd be observing his future self closely, looking for signs of danger or changes in his personality. And then there's Captain America, who would likely approach the situation with a sense of duty. He'd be thinking about how this meeting could help or harm the world and the Avengers as a whole. Overall, it depends on the character's personality and what they value most.
Some Avengers might be cautious and try to observe first. For example, Iron Man could use his technology to analyze the situation before approaching past characters.
If the Avengers go to the future in fanfiction, it would be a wild ride. They could find that the Earth has been taken over by an alien race that they've never seen before. Their powers might not be as effective as they are in the present. They would have to adapt quickly, learn about the new political and social structures in the future, and find a way to either prevent this future from happening if it's a bad one, or ensure that it comes to pass if it's a good one. They might also have to deal with time paradoxes, like if they change something in the future, it could have a ripple effect on their present.
They might encounter their past selves. In some fanfictions, they could try to prevent certain events from happening without changing the overall timeline too much. For example, they may stop a minor villain from getting a powerful weapon in the past.
Some Avengers would be excited. They'd see it as a great opportunity to connect with their future lineage.
It could become more tense. If they see different versions of themselves or different outcomes for their relationships, it'll cause stress. For instance, if Vision sees a future where he and Wanda are separated, it'll be tough on their relationship in the present.
They react differently. Stark might immediately start thinking about how to improve the tech in the movies. Cap is likely to be more focused on the story and the characters' motives.
When it comes to reading Endgame fanfiction, the Avengers' reactions are diverse. Thor, with his jovial nature, would likely enjoy the creative liberties taken in the fanfiction. He may even be inspired by some of the new storylines. Steve, being the more traditional and values - oriented one, may have a hard time accepting fanfiction that goes against the moral code he adheres to. Tony would approach it with a mix of amusement and scrutiny. He would be entertained by the creativity but also quick to point out any flaws in the logic or characterization. Natasha would be on the lookout for how her character is developed in the fanfiction, hoping for accurate and strong portrayals, while Bruce would be intrigued by the scientific concepts, whether accurate or not, that are explored in the fanfiction.
Future Loki might interact with the Avengers in a cautious way. He knows their past opinions of him and tries to prove himself. He could start by sharing small bits of useful information. For example, he might tell Iron Man about a weakness in a new enemy's technology.
There could be characters who are skeptical. They might not believe what they read in the fanfiction about their future and dismiss it as just some wild imagination. After all, it's not part of their official story. For example, a very traditional and by - the - book character might not give any credence to the fanfiction's version of the future.