Some of them might be shocked. Tony Stark, for instance, might immediately start thinking of ways to use technology to change what he saw. Steve Rogers would probably be more concerned about the moral implications of interfering with the future.
Well, they might see a lot of different things. Maybe they'd see new threats emerging and start preparing for them right away. They could also see changes in their relationships, like friendships turning sour or new romances forming.
In most cases, watching (reading) fanfiction is legal as long as it doesn't violate copyright laws in a major way. Fanfiction is often a derivative work, and as long as it's not being sold commercially without permission from the original copyright holder and is more of a non - profit creative exploration of existing works, it's usually okay.
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.
Some characters would likely be entertained. For instance, Loki might enjoy seeing the various ways fans write him as a more complex anti - hero. He'd probably find the creativity in the fanfiction quite appealing.
I think Levi could benefit as well. His combat skills are already top - notch, but seeing the future could help him anticipate enemy attacks even better. He could train his squad more effectively based on the future battles he witnesses, ensuring their survival and making them even more formidable against the Titans.
I'm not entirely sure specifically as there could be many different takes on it. It might be a fanfiction related to Breath of the Wild (BotW) where the characters are somehow watching the future. Maybe it involves Link or Zelda having visions of what's to come in the game's world.
Some popular platforms for fanfiction in general could be Archive of Our Own (AO3). It has a vast collection of various types of fanfiction, including those with futuristic themes. Another one could be FanFiction.net, which also hosts a large number of stories. Wattpad might also have some future - themed fanfiction, although it has a broader range of content.
I'm not sure specifically as there could be many different interpretations in such a fanfiction. It might be about the members of BTS observing possible future scenarios, perhaps related to their careers, relationships, or the world in general.