Some of them might be amused. For instance, Hulk could find it funny if Godzilla was shown as being weak in the fanfiction. He might laugh and say 'That big lizard not so tough!'.
Black Widow would likely analyze the fanfiction from a strategic point of view. She'd be thinking about how Godzilla's abilities could be used or countered if it was a real situation. And Hawkeye might just be shaking his head in disbelief at the whole concept of the Avengers and Godzilla in the same story.
The Avengers as a whole might have a big discussion about the Godzilla fanfiction. They could debate whether it was a good or bad idea to mix their world with Godzilla's. They might also start coming up with their own versions of how they would interact with Godzilla if they ever met in a story. It could lead to some creative ideas and also some arguments among them.
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.
If the Avengers read Naruto fanfiction, different members would have different reactions. Bruce Banner might study the way the characters control their inner power, like how Naruto controls the Nine - Tails' chakra. Steve Rogers might be more focused on the moral lessons in the stories. He would look for similarities and differences between the values in the Naruto world and their own. Natasha Romanoff could appreciate the complex relationships between the characters, just like she values her relationships within the Avengers. And Clint Barton would probably enjoy the action - packed parts, imagining how he could use some of the ninja skills in his own battles.
They'd probably be very entertained. Thor is a larger - than - life character, and fanfiction often takes things to the extreme, which would be a source of amusement for the Avengers.
Naruto would probably be both amazed and a bit scared at first. But being Naruto, he would quickly jump into action. He might try to use his rasengan against Godzilla, thinking it could do some damage. However, he would soon realize that Godzilla is much more powerful than he initially thought and would have to come up with a different strategy, like using his speed to avoid Godzilla's attacks and find its weak points.
They'd have diverse reactions. Steve would likely be a bit embarrassed. Thor might find it strange as it's not like the tales in Asgard. Natasha would probably analyze it from a psychological perspective. Tony would be quick to point out any inaccuracies or plot holes.
Tony would likely laugh at some of the more out - there plot ideas. He'd probably think he could come up with better technology than what's in the fanfic. Steve would be more open - minded and might enjoy the creativity. Thor would be like 'This is not like any Midgardian story I've heard!'.
Some Avengers might be amused. For instance, Tony Stark would likely find it a fun distraction from his usual high - tech world and might even make sarcastic comments about the plot or characters. He could say something like 'These wizards should really upgrade their transportation - brooms? Seriously?'.
The Avengers' reactions would vary widely. Tony Stark, being the tech - savvy and quick - witted one, would probably be making jokes left and right about the fanfiction. He might say things like 'Why do they need a sword when they could have a laser - sword?' Captain America, on the other hand, would be more respectful. He'd try to understand the cultural and mythological aspects of the story. Hawkeye would probably be a bit indifferent at first, but as the story goes on, he might get more interested in the action parts of the fanfiction.
Bruce Banner, when he's not in Hulk mode, would be really interested in the scientific aspects that might be hidden in the Percy Jackson fanfiction. Even though it's a world of magic, he could look for ways that the magic could be related to some kind of scientific principle. He might also be interested in how the characters control their powers, whether it's Percy with his water powers or the Avengers with their various abilities, and look for similarities in self - control and management of power.
Some of them would be entertained. Iron Man might laugh at the strange spells and potions. Hulk might not understand much but could enjoy the action parts if there are any. Thor could be curious about the magic and how it compares to his Asgardian powers.