Perhaps Peter discovers a new threat that is specifically targeting his loved ones because of his Spiderman identity. To protect them, he decides that the only way is to stop being Spiderman. He might try to live a completely normal life, away from the superhero world, and hope that the danger will pass his family and friends by.
Maybe Peter gets tired of the double life. He realizes that being Spiderman has cost him too much, like his normal relationships or his own mental health. So he decides to give up the mantle.
It could be a new villain who manages to make Peter question his role as Spiderman. This villain might use mind - games or expose Peter's identity in a way that makes him want to give it all up.
In fanfiction, if Spiderman stops the Civil War, he might use his charm and quick thinking. He could talk to both sides, making them see the bigger picture. Maybe he reveals some hidden truth that makes everyone realize they've been misled. For example, he could expose a villain's plot to divide the superheroes.
Well, perhaps in the fanfiction, Spiderman saves a woman who later turns out to be pregnant with his child. He doesn't know about it until she shows up at his doorstep with the baby. Spiderman then has to figure out how to take care of the baby. He might start using his web - slinging skills in new ways, like creating a safe web - hammock for the baby to sleep in while he's on patrol, and he has to deal with the reactions of his friends and allies, like Mary Jane or Ned.
Perhaps Peter is alone in a forest, away from the city. He's there to find some peace and quiet, to get away from the chaos of New York. While he's alone, he reflects on his powers and how they've both blessed and cursed him. He might even start to train in new ways, using the seclusion of the forest to his advantage.
Peter might have an internal monologue about his loneliness. For example, he could be sitting in his room, staring at the ceiling, and thinking about how he can't really share his true self with anyone. He misses having a normal life where he doesn't have to constantly hide his identity.
In a 'Peter slaps Edmund fanfiction', it could start with a misunderstanding. Edmund is wrongly accused of stealing or lying, and Peter, believing the false information, lashes out and slaps him. The rest of the story could be about the search for the truth, how Edmund feels wronged, and how Peter realizes his mistake. It might also involve the relationship between the two characters being strained at first and then gradually repaired as the truth comes to light.
Maybe Peter punches Steve because of a misunderstanding. For example, Steve might have been wrongly accused of something that Peter holds dear, like endangering his family or friends. In his anger, Peter decides to take matters into his own fists.
Maybe Peter inherits Tony's high - tech gadgets. For example, he could get access to some of Tony's Iron Man tech, which would be a huge deal. This could set him on a new path in his superhero journey, perhaps allowing him to upgrade his own suit or develop new abilities.
In the fanfiction, Maryjane could be in love with someone else at the time. Even if she has some feelings for Peter, her stronger feelings for another person make her reject Peter. Also, Peter might have done something in the past that Maryjane can't forgive, like lying to her, which results in the rejection.
One possibility is that the story is told from the perspective of a side character who has just discovered Spiderman's existence. Without the origin story, we could see how this character tries to figure out who Spiderman is, what his motives are, and how he got his amazing abilities. This could lead to a lot of mystery and speculation, and as the story unfolds, we gradually learn more about Spiderman's current situation and the threats he's facing through the eyes of this new character.