Peter may run away. He could be so embarrassed and hurt that he just wants to get away from the situation. He might go to a quiet place to think about what he has done wrong and how he can make it up to the Avengers.
Peter might be very defensive at first. He could argue back, trying to explain his actions. After all, he is a teenager with his own ideas and he may think that the Avengers don't fully understand his perspective.
He could also be really shocked and start to feel guilty. Peter looks up to the Avengers, and having them yell at him would be a big blow. He might stand there in silence, with his head down, realizing that he has disappointed them.
It could be that Peter's immaturity showed in a crucial situation. He might have been over - confident and tried something really risky without thinking it through. The Avengers, being more experienced, would be frustrated with his recklessness and thus yell at him. They want him to learn and grow, but his actions might have been too much to tolerate at that moment.
He might also get angry. Peter has a strong sense of justice. If he feels that the Avengers are being unfair, he could stand up to them. He'll use his quick wit and his powers to show that he's not going to be pushed around easily.
Peter might get a bit flustered at first. He's young and looks up to the Avengers, so being made fun of could make him blush or stammer. But then he usually bounces back with a witty comeback of his own. For example, he might say something like 'Well, at least I don't have an old - fashioned shield' to Steve if Steve teases him about his suit.
Peter is likely to be in awe. He might be a bit nervous at first, but also extremely excited. He has looked up to the Avengers for a long time, so meeting them would be like a dream come true. He would probably be stuttering a bit as he tries to introduce himself and show his respect.
Peter usually blushes a lot. Since he's a shy and somewhat awkward teenager, his face turns bright red when the Avengers embarrass him. He might stutter while trying to defend himself or come up with an excuse.
Natasha Romanoff could show her emotions in a more subtle way. She might look at Peter's old things and a small smile would cross her face as she remembers his innocence and determination. Thor, on the other hand, might become more determined to protect the world in Peter's honor, as he respected Peter's strength despite his young age.
Peter could also be very nervous. He's still a young hero and being called by the Avengers in such a public setting like in class could make him feel self - conscious. He might stutter when he tries to answer their call and fumble with his things as he gets ready to leave. He'd be thinking about all the possible things they could need him for and whether he's really up to the task while also dealing with the eyes of his classmates on him.
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.'
Another reason could be related to Peter's mistakes. He may make errors during a mission that put the whole team or the city at risk. Tony, who has a lot of responsibility on his shoulders, might yell at Peter as a way to make him understand the seriousness of his actions and to prevent future mistakes.
Tony Stark might immediately rush to his side and start scanning him with his high - tech gadgets to find out what's wrong. He'd be worried as he sees Peter as a sort of protege. Captain America would probably be more of a calming presence, trying to keep everyone else from panicking while waiting for medical help if needed.