Well, they might be shocked and full of regret. They would see all the mistakes that led to Thanos' victory in Infinity War. Maybe they'd start arguing about who was responsible for what went wrong, like Stark might blame Steve for not being there with them earlier, and Steve would counter about Stark's overconfidence with the whole Ultron situation which might have weakened their position against Thanos in the first place.
Some of them could be in denial at first. They might think it was some sort of trick or false vision. But as they watched more and more of Infinity War, they'd have to accept the reality. Then, they'd start to think about how to use this knowledge. Maybe they'd try to find a way to go back in time like Dr. Strange did in the real movie, or find a weakness in Thanos that they didn't notice before.
It would be quite a strange situation. Maybe they'd be amused or confused. For instance, if they read some out - of - character fanfic, they might be really puzzled. Like if Thor was depicted as a coward in the fanfic, his fellow Avengers might have a good laugh or be a bit shocked.
Well, Tony Stark would probably make sarcastic comments throughout. He might say something like 'This Godzilla thing is interesting, but our battles are way cooler.' Steve Rogers would be a bit confused at first, trying to understand the whole concept of fanfic. Thor might think it's some sort of Midgardian strange tale and compare Godzilla to a mythical beast from Asgard. And Hulk? He'd probably just be bored and want to smash something if it goes on too long.
Aquaman would likely be intrigued by the otherworldly settings and creatures in Infinity War. He might think about how the underwater world he rules could be affected if something like the events in the movie occurred. Green Lantern, if included in the Justice League for this scenario, would be concerned about the scope of power Thanos wields and how the Lantern Corps could handle such a threat.
Well, Tony Stark would probably be making sarcastic comments throughout the reading. He might say something like 'This is quite the creative take, but really, do they think I'd act that way?' Steve Rogers would be more serious, perhaps thinking about how the fanfic version compares to the real events. And Thor? He'd probably be a bit confused at first and then start laughing at some of the more outlandish parts.
If the Avengers watched Iron Man fanfic, it would be an interesting sight. They would see all kinds of alternate universes and characterizations of Iron Man. Some of the Avengers might be inspired by the creativity of the fans. For example, Rhodey might see new ways to improve Iron Man's suits in the fanfic and think about applying some of those ideas in their real - world (within the MCU) situations. But others like Vision might find it difficult to understand the more emotional and unstructured nature of fanfics as he is used to a more logical view of things.
If the Avengers watched Avengers fanfiction, they would probably have a range of reactions. Hulk might not understand most of it and just get frustrated. Black Widow, on the other hand, would be very observant and might pick up on the different characterizations of herself. She could either like the more complex and nuanced versions or be annoyed by inaccurate portrayals. And Hawkeye might be indifferent at first, but then get drawn into the more action - packed and adventure - filled fanfictions.
They might be really surprised. Some of them would probably find it hilarious while others could be a bit offended if the fanfiction misrepresents them. For example, Thor might be amused by the grand adventures people write about him, but Tony Stark might be critical if the fanfiction makes him look dumb.
Well, Percy could use his water powers to counter some of Thanos' attacks. Maybe he could create huge water waves to disrupt Thanos' army. He could also use his skills in combat, which he has honed from fighting monsters, to take on some of the minions. And his ability to heal in water could give him an edge in a long - drawn battle.
One possible plot could be the Avengers watching the events unfold in Infinity War and constantly making comments about their own actions. For example, Thor might be yelling at his past self for not going for the head when he had the chance against Thanos. They could also be strategizing on how they could have changed the outcome, leading to some interesting in - group debates and revelations about their relationships with each other.