Sometimes, Peter may just stand there and take the yelling, feeling guilty about whatever he did wrong. He respects Tony a great deal, so he doesn't talk back immediately. However, later he might go off on his own to think about how to improve and make it up to Tony.
Peter might be initially shocked and a bit scared. After all, Tony is like a mentor to him. But then he could become defensive, trying to explain his actions or point of view.
Perhaps in the fanfic's storyline, Tony is facing a lot of pressure himself, like threats from powerful villains or issues within the Avengers. Peter's actions, whether they are mistakes or just inconvenient timing, could be the straw that breaks the camel's back for Tony, causing him to yell at Peter.
Peter might be embarrassed at first. He's been idolizing Spider - Man and now Tony, a real - life hero - like figure, knows about it. But then he realizes that Tony could be an even greater source of knowledge and support, so he becomes more open about his love for Spider - Man.
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.
Perhaps Peter is a bit annoyed at first. He's trying to focus on class and here's Tony calling. But then when he realizes it might be something important, he starts to pay more attention to the call, all while being cautious not to get caught by the teacher.
Tony could be initially shocked. He might not understand why Peter would run away, especially if they had a good relationship before. He'd probably start searching for Peter right away, using all his resources.
On the other hand, it could also be a turning point for the better. Sometimes a big outburst like that can clear the air. They might realize they've been misunderstanding each other and start to work on their relationship more effectively after the initial shock of the yelling.
Stiles usually reacts with a mix of fear and defiance. He's afraid because he's in a dangerous situation, but his strong - willed nature makes him defiant. For example, in many fanfictions, he'll shout at Peter, trying to show that he won't be easily broken.
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.
Perhaps Peter failed to follow Tony's instructions regarding some important technology or protocol. Tony, being a perfectionist and concerned about safety, would then yell at Peter for not listening. In the fanfiction world, this kind of conflict adds drama and tension to their relationship.
Perhaps Tony, knowing Peter's character, is somewhat expecting the interruption. He might have a wry smile on his face and then listen to what Peter has to say. He could also play it cool and make a joke about Peter's eagerness to interrupt his meeting, while still giving Peter a chance to explain his reasons.