The story could focus on Tony's downward spiral into guilt and self - blame. He might isolate himself from the other Avengers, feeling that he should have been the one to die. His technological advancements could take a dark turn as he tries to find a way to bring Peter back, perhaps even dabbling in dangerous and unethical science.
Another possibility is that the other superheroes, especially those close to Peter like MJ, would take up Peter's mantle in a way. They could be inspired by his sacrifice and become more involved in fighting crime and protecting the city. Meanwhile, Tony would be in the background, a broken man, until something or someone helps him to see that Peter's sacrifice was meaningful and he should continue to fight for the good they both believed in.
One possible scenario in such a fanfiction could be that Peter, in a self - sacrificing move, takes on a powerful enemy that was originally meant to target Tony. Maybe Peter's inexperience and pure heart lead him to misjudge the danger, and he ends up giving his life to save others, while Tony is left to grapple with the guilt.
One possibility is that Tony calls Peter to discuss an upcoming science project. Maybe they need to work together and Tony wants to plan out their tasks in class so they can start right away after school.
Well, one possibility is that Peter gets in trouble for answering the call during class. Maybe he tries to be sneaky but the teacher catches on. For example, he could be whispering into the phone and the teacher hears him and confiscates his phone.
Perhaps when Tony picks up Peter, there's some sort of danger lurking nearby. So they end up having an impromptu adventure on the way back. Tony could show off some new gadgets to Peter to deal with the threat.
One possibility is that they could stop at a diner on the way home. Tony might give Peter some advice about his schoolwork or his superhero training. They could also discuss the latest events in the superhero world.
Well, Tony might get angry at first. He's used to being in control and having his orders followed. But then he could also realize that Peter has a point. Maybe they would have a big argument that leads to Peter leaving the team or Tony having to re - evaluate his plans.
Well, one possibility is that a new hero could emerge in his place. Maybe one of his friends or a previously unknown character with powers would step up to protect the city. For example, Miles Morales could become even more prominent earlier than in the regular storyline. The city would be in chaos without Spider - Man, so the police might have to step up their efforts in a new way.
One possibility is that Peter gets really flustered. He might be in the middle of paying attention to the teacher when Deadpool calls, and his first reaction could be to try and hush Deadpool. Since Peter is often portrayed as a responsible student, this unexpected call could throw him off his game in class.
Well, Tony might be initially surprised. He could then start to use Peter's love for Spider - Man to his advantage. Maybe he'd give Peter more tasks related to Spider - Man tech, knowing that Peter would be more motivated. He might also start to train Peter in a way that's inspired by Spider - Man's abilities.
One possible plot development could be that Peter is left with a huge sense of guilt. He might struggle with survivor's guilt, constantly thinking that it should have been him. He could then become overly reckless in his superhero activities, trying to prove that he was worthy of being saved. Another aspect could be how the other Avengers deal with Tony's death. They may turn to Peter as a symbol of hope, since Tony sacrificed himself for Peter. This added pressure on Peter could lead to him either rising to the occasion or crumbling under it.