Well, perhaps Peter is frustrated with the Avengers for not including him in a crucial mission. Maybe he feels overlooked and underestimated, so he yells at them to voice his anger and disappointment.
The main antagonist could be the Avengers' own bureaucracy or leadership structure. Peter might be yelling at them because their rules and decision - making processes are preventing them from doing the right thing. He might see this as a hindrance to their ability to protect the world effectively and is frustrated enough to yell at them to try and bring about change.
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 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.
One way is by getting involved in Peter's school life in a more official capacity. Maybe they could arrange for some anti - bullying seminars at the school. Natasha could also train Peter in stealth and evasion techniques so that he can avoid the bullies more easily. Thor could even offer to be Peter's bodyguard for a while, at least until the bullying situation is resolved.
Well, in this fanfiction, Peter Parker might meet the Avengers in a more casual setting. For example, he could be at a science expo where some of the Avengers are also present. Peter is there to show off his latest web - shooter design. The Avengers notice his intelligence and his unique abilities as Spider - Man. They then start a conversation with him, and from there, a relationship between Peter and the Avengers begins to form. This could lead to Peter getting involved in more Avengers - level missions and growing as a hero.
Well, in many fanfictions, the Avengers protect Peter by always having his back in battles. For example, Captain America might shield him from incoming attacks with his iconic shield. They also offer him guidance. Tony Stark could be constantly giving him advice on how to improve his suit and combat skills.
Maybe Peter misses an important training session. Tony has probably put a lot of effort into training Peter to be a better superhero. If Peter skips out on training for something unimportant, like going to a party or just being lazy, Tony would be justifiably angry and yell at him for not taking his superhero responsibilities seriously.
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.