They might be confused at first. Fanfiction can be wild and different from their real experiences.
Some Avengers might be flattered if the fanfiction portrays them in a heroic light. Others might be annoyed if it shows them in a negative way. For example, Hulk might not like it if he's shown as out of control all the time in the fanfiction.
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.
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.
Some would be intrigued. Captain America, being an open - minded person, might be interested in seeing different interpretations of their team dynamics. He could even gain new insights about his relationships with his fellow Avengers through the fanfiction.
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.
The characters might also get confused. Fanfictions often have their own unique plotlines that can be quite different from the official story. So when they see these strange twists and turns, like Thanos suddenly becoming good in the fanfiction, they'd be scratching their heads and trying to figure out what's going on.
They would probably have a range of reactions. Some might be entertained, while others would be more critical. Stark might joke about the science in it not being as good as his own tech.
Tony Stark would probably be really critical at first. He'd be looking for any plot holes or scientific inaccuracies. Thor might be a bit confused at some of the more modern or out - there concepts. Captain America, on the other hand, would be more interested in how the fanfics uphold the values he believes in.
Some of them would be amused. Hawkeye might chuckle at the outlandish scenarios in the fanfic. Black Widow would be more reserved but still interested. She'd be quietly observing and thinking about the implications of the story. Captain America would try to find the moral of the story, if there is one, as he always does.
Some would be excited. Luffy would probably be eager to jump into the future he sees in the fanfiction. He's always looking forward to adventures, and if the future seems cool, he'd be all for it.
The reaction of Star Wars characters to watching the future in fanfiction would vary greatly. Consider Obi - Wan Kenobi. He would be calm and analytical, trying to understand the different paths the future could take. He might be looking for signs of the Force's influence and how he could help guide the right choices. And the stormtroopers? They might be confused at first, as they are used to following orders, but then some might start to question their roles in the future if they see a different way of life or a more just society.