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.
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.
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.
In a fanfiction where the Avengers go to Hogwarts, there would be a clash of cultures. The Avengers are used to a world of high - tech and superpowers based on science, while Hogwarts is all about magic. Iron Man would likely be skeptical of magic at first, but as he sees the power it holds, he might start to think of ways to integrate it with his technology. The students at Hogwarts would be in awe of the Avengers, and the Avengers would have to learn to respect the magical world's traditions.
In fanfiction, if the Avengers go to Asgard, there could be a big clash at first. The Asgardians are proud warriors and the Avengers have their own ways. But then they might team up to face a common threat. For example, a powerful dark magic user could be targeting both Earth and Asgard. The Avengers with their diverse skills and the Asgardians with their magic and strength could form an unbeatable alliance.
Well, it depends on what he changes in the past. If he stops certain villains from emerging, the future of the Avengers could be one of relative peace. They might be able to focus on more positive things like exploring the universe or helping humanity in a more proactive way. However, if he changes things in a way that disrupts the natural order too much, it could create new and unexpected threats that the Avengers are ill - equipped to handle.
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.
Probably Heimdall. He guards the Bifrost, the Rainbow Bridge that leads to Asgard. He has the ability to see all, so he'd be the first to spot the Avengers coming. And he's not one to let just anyone pass without a bit of interrogation.
Well, they'd probably cause quite a stir. Thor might mistake his magic for his own godly powers and try to show off. Iron Man would be fascinated by all the magical technology and start thinking of ways to integrate it with his suits. And Captain America would be a bit out of place at first, but his sense of justice would fit right in with the Hogwarts values.