Another reason might be related to some sort of experiment gone wrong. Peter is often involved in scientific research. If there was an accident in his lab, perhaps with a new type of spider - related serum or some other experimental technology, it could have unforeseen consequences on his heart and lead to it stopping.
In some fanfictions, Peter could have a sort of out - of - body experience. He might meet some important figures from his past or gain some new insights while his heart is stopped. This could then influence the way he approaches life and heroism once he is revived. And when he is revived, he might come back with new powers or a stronger sense of purpose.
One possible reason could be extreme exhaustion. Peter Parker has a double life as a student and Spider - Man. He might be overworked, not getting enough sleep, and his body just gives out. For example, he could have been fighting multiple villains in a row without a break.
Perhaps after facing too much betrayal from the village he loves. If the villagers turned on him despite all his efforts to protect them, it might lead him to close his heart in self - defense, not wanting to be hurt again. He's always tried so hard to gain their acceptance and if that was all for naught, it would be a huge blow.
One possible reason could be a difference in ideology. Maybe Peter Parker feels that Stark's methods are too extreme or not in line with his own moral compass. For example, Stark might be involved in some projects that Peter doesn't agree with, such as using certain unethical technologies in the pursuit of justice.
He might think it's not in line with the real Steve. Fanfiction can be quite far - fetched sometimes.
Well, it might be an exploration of the psychological toll of being a superhero. Peter Parker constantly faces danger, loss, and has to keep his identity a secret. Writers may create 'suicidal peter parker fanfiction' to show how all these factors could potentially break him. Also, in the context of fanfiction, it could be a way to subvert the typical heroic narrative and show a more vulnerable and broken side of the character. However, it's a very heavy and potentially triggering topic.
Well, one reason could be that he's on a secret mission for S.H.I.E.L.D. that requires him to go undercover and cut off all contact. Maybe he's investigating a new super - villain threat that's too dangerous to let anyone know about.
Maybe it's due to a new and powerful enemy's attack. In fanfiction, authors might create unique villains with abilities that specifically target Peter's weaknesses. For example, if the villain has the power to disrupt Spider - Man's enhanced senses, it could cause Peter to be disoriented and ultimately collapse. Another aspect could be that Peter overuses his powers without proper rest, which exhausts his body and causes him to collapse.
Some writers might do it for shock value. They want to create a very different and extreme take on the character to get a strong reaction from readers.
One reason could be extreme guilt. Maybe he failed to save someone important and can't bear the burden of that failure. In some fanfictions, if he accidentally caused harm to his loved ones, like Aunt May getting hurt because of his superhero activities, the guilt might be overwhelming.