Imagine the Avengers watching Naruto fanfiction. Loki, if he was part of the group at that time, would be intrigued by the different power systems and the complex relationships in the Naruto story. He might even try to use some of the ideas from the fanfiction in his own schemes. Wanda Maximoff could relate to some of the characters' emotional struggles in the fanfiction. Vision would be trying to understand the cultural context behind Naruto and how it influenced the fanfiction. And all of them together would make for a very interesting viewing experience.
The Avengers would have a range of reactions. Natasha Romanoff might analyze the characters in the Naruto fanfiction like she does with her targets. She'd look for their strengths and weaknesses. Bruce Banner, when not in Hulk mode, would be interested in the scientific aspects of the Naruto world if they were mentioned in the fanfiction. Clint Barton would probably just be along for the ride, laughing at the more comical parts and enjoying the break from all the superhero stuff.
They might be amused. Tony Stark himself would probably be quite smug, seeing all the creative ideas fans have about him. Steve Rogers might be a bit confused at first by some of the more out - there concepts in the fanfiction. Natasha Romanoff would likely be quietly observant, picking up on the different characterizations of Iron Man in the stories.
The Avengers might have a range of reactions. Tony Stark could be making sarcastic comments throughout, perhaps critiquing the plot holes in the fanfiction. Captain America might be a bit confused at first, not fully understanding the concept of fan - made stories, but then getting into the spirit of it. Thor would probably find the whole thing quite amusing and laugh heartily at the more outlandish parts.
Well, Tony might be intrigued by the new take on Wanda's powers shown in the trailer. He'd probably start making theories about how her reality - bending could be either a great asset or a huge threat. Steve, on the other hand, would be more concerned about Wanda's mental state. He'd remember how she lost Vision and wonder if this new 'WandaVision' world she's in is a way of her coping or something more sinister.
The Avengers might be really excited. Tony Stark could be making witty remarks about Spider - Man's new suit in the trailer. Captain America would probably be proud to see a new hero emerging. And Thor might be a bit confused at first but then get into the cool stunts shown.
Well, Tony Stark might be impressed by the display of power in the trailer. He'd probably start making some snarky remarks about how he could upgrade her suit or something. Thor could be like, 'She seems to have the strength of a true warrior!' Natasha might be sizing her up, thinking about how she could work with Captain Marvel in a fight.
They might have a range of reactions. Some, like Tony Stark, would probably be amused and might even give snarky comments about the plot or the writing. He could be seen making fun of the inaccuracies in the fan - made stories compared to the real events they've been through.
Some characters might be shocked. For example, Naruto himself. He has always been full of hope for the future and worked hard to build a better world. If he saw a future that was not as positive as he expected, he would be very disappointed at first. But then he would surely try to find a way to change it, because that's his nature.
Well, Steve Rogers might be a bit confused at first. He's from a different era and fanfiction is a very modern concept. But he'd probably be polite about it and say something like 'It's interesting to see how fans imagine different scenarios with Yelena.' Tony Stark, on the other hand, would likely be more intrigued. He might chuckle and say 'This is some creative stuff. I wonder what else they come up with about Yelena.' And Thor would probably just be like 'This is a strange Midgardian thing, but if it makes people happy, then so be it.'
Tony Stark would likely find it hilarious. He'd probably be the first one to start making jokes about it. He might say 'Oh, Hawkeye, you've got some really creative fans out there. I should hire them to write my memoirs!'. As for Hulk, he probably wouldn't care much. He might just grunt and go about his business. But if he did read some, he might not understand it very well and get frustrated. Hawkeye himself would probably be embarrassed at first, but then he'd start to see the humor in it and might even enjoy some of the more positive fanfiction about him.
Some Avengers might find the memes in fanfiction hilarious. For example, Tony Stark would probably have a witty comment about how creative the fans are. He might even be inspired to create some tech based on the meme concepts. Steve Rogers, on the other hand, would be a bit more confused at first. But after some explanation, he would start to see the humor in it and might shake his head with a smile. Thor would likely not understand most of it, but would laugh along just to be part of the group.