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.
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.
It could also be due to jealousy. Peter might be getting too much attention from the public or other superheroes. His youth and new - found popularity could make the more established Avengers feel overshadowed, leading to feelings of resentment towards him.
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.
Well, it could be due to misunderstandings. Fanfics often play with the idea that Peter, being young and inexperienced, might accidentally cause trouble that the Avengers misinterpret as intentional. For example, he could be trying to help but ends up making a situation worse, leading to the Avengers' dislike. Another reason could be that some writers like to create drama by pitting characters against each other. They think it makes for a more interesting story if the Avengers have this negative view of Peter Parker, even if it goes against the more positive portrayals in the official comics or movies.
In some fanfics, Peter might faint due to overexertion. He's often depicted as being involved in intense battles or using his powers to the extreme. For example, if he's been fighting a powerful villain for a long time without a break, his body could just give out and he faints.
Well, in some fanfictions, the Avengers might hate Peter because of jealousy. Maybe Peter's powers are so unique and he gets a lot of attention, making some Avengers feel overshadowed.
It might be due to jealousy. Peter is young and has a lot of potential. Some of the Avengers could feel threatened by his rapid growth and popularity, especially if he starts getting more attention from the public or from S.H.I.E.L.D. than they do.
They might notice signs like Peter being overly withdrawn, flinching at sudden movements, or having unexplained injuries. Maybe they see him constantly on edge around certain people.
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.
In fanfictions, the Avengers are often overprotective of Peter because he's young and inexperienced compared to them. He's like a little brother or a son figure to many of them. For example, Tony Stark sees in Peter a younger version of himself and wants to prevent him from making the same mistakes he did. So, he's overly cautious.