In fanfiction where the Avengers meet Peter's girlfriend, how would the Avengers react?

The Avengers might react in different ways. Steve Rogers would probably be polite but firm in getting to know Peter's boyfriend. He'd want to ensure that he was a good influence on Peter. Thor, on the other hand, might be a bit more boisterous. He could either be really friendly and enthusiastic, or his loud and powerful presence might accidentally scare the boyfriend a bit.

They might be cautious. After all, they don't know her and she's from Percy's world which could be full of unknowns for them.

They would be all over him! Steve would probably have a big, warm smile on his face and just be in awe of how small and precious he is. Clint would make silly faces to make the baby laugh. Bruce might be a bit more cautious at first, but then he'd be charmed by Peter's little giggles.

They might be shocked at some of the dangerous situations Peter has been in without their knowledge. They could feel guilty for not being there to protect him more. And they would likely be very proud of his selfless acts.

The Avengers would initially be in shock when they find out Peter is sick. Clint Barton would be the one to keep a calm head and start organizing things. Wanda Maximoff would try to use her powers to ease Peter's pain if possible. Vision would use his vast knowledge to try and find a solution. They would all be very concerned and do everything they can to make Peter better, from getting the best medical help to providing a safe and comfortable environment for him to recover.

Iron Man, on the other hand, might be more direct. He could use his technology to track Peter's actions and confront him. He might threaten to expose Peter's identity if he doesn't stop. And Thor would probably be angry at first. He values his fans a great deal and seeing Peter bully them would make him want to use his hammer to teach Peter a lesson, but then he would also try to understand the situation.

Tony Stark might use his quick wit and technology. He could immediately scan Peter to make sure there's no physical danger causing the hyperventilation. Then he'd probably crack a joke to try and calm Peter down, like 'Kid, you breathe any faster and you'll fly away like a human jetpack.'

Peter might be really nervous at first. He's used to being just the friendly neighborhood Spider - Man, and now the Avengers know he's Tony's son. He could be worried about living up to their expectations.

Thor would likely be the most affected. He has a history with Fenrir as it is from Asgardian mythology. He might be cautious at first, but also feel a sense of kinship. Iron Man would probably be all about analyzing Fenrir, trying to figure out its weaknesses and strengths. Captain America would be on guard, ready to defend his team, but also open to the idea of Fenrir not being an enemy if proven so.

They would probably be very surprised. Some might laugh at the creative ideas in the fanfiction.