It could be the pressure of being 'The Boy Who Lived'. Harry has so much expected of him all the time, and it might just be too much to bear.
Perhaps it's the loss of his parents and the feeling of being alone in the world. He has friends, but there's still a void that he can't seem to fill. Also, the constant threat from Voldemort and his followers is a huge stressor. All these things combined could drive him to such a desperate act as cutting himself in the fanfiction.
In the fanfiction, Harry could be cutting himself due to the bullying he endures at school, not just from the Slytherins but also from the general pressure of living up to the Gryffindor image. He might feel like he can't talk to anyone about his real feelings, not even his best friends. The fact that he has to constantly face challenges that are way beyond his age level, like fighting dark wizards and dealing with the mystery of the Horcruxes, could also be pushing him over the edge.
Well, Snape has always had a complex relationship with Harry. When he finds Harry cutting himself in this fanfiction, he might be angry at first, thinking it's a sign of weakness. But then, as he realizes the depth of Harry's pain, he could soften. He might start to see Harry more as a troubled child rather than just James Potter's son. Snape could use his knowledge of potions to create something to heal the physical wounds and also try to offer some form of emotional support, albeit in his own gruff way.
One possible reason could be his self - loathing. He has a complex past and has made many difficult choices. In fanfiction, the authors might explore his inner turmoil through self - harm as a way of expressing his pain. He may feel that he doesn't deserve any better because of his actions and mistakes.
In the fanfiction world, if Snape finds Harry cutting, he might be initially shocked and angry. He could see it as a sign of Harry's inner turmoil. Snape, despite his complex relationship with Harry, might feel a sense of responsibility. He might immediately take steps to stop Harry from further harming himself, perhaps using his magic to heal the cuts. And then he would likely question Harry about why he was doing such a thing, trying to get to the root of the problem.
One possible reason could be extreme stress. Peter Parker has a lot on his plate, being Spider - Man and having a normal life. If in the fanfiction he faces a series of really tough situations like failing to save someone important or being hunted by a very powerful enemy, the stress might get to him and lead to self - harm as a way of coping. Another reason could be feelings of isolation. Even though he has friends, he might feel like no one truly understands the dual life he leads, so in the fanfiction this could drive him to such a desperate act.
It is inappropriate because the Harry Potter series is a source of inspiration for many, especially young readers. Depicting a main character like Harry in such a self - destructive act can have a bad influence on those who look up to him. Also, self - harm is a very personal and often traumatic topic that doesn't belong in a fictional world that is supposed to be a form of escapism. The Harry Potter world is about magic and adventure, not self - harm.
Perhaps Harry was investigating something related to Voldemort on his own and got in over his head. He could have been captured by Voldemort's followers who were hiding him away. It's also possible that a magical spell backfired on him while he was practicing magic in a secluded area and it made him disappear, only to be found later by Snape.
Well, it could lead to a major turning point. Snape might be shocked and try to help Harry get the support he needs.
Perhaps he likes to see how fans re - imagine his character. He might be curious about how others view his actions and motives throughout the story.
It could be a failed experiment in potions class. Hermione is always eager to try new things in potions, and perhaps this time it backfired, causing her some harm. And Snape would be the one to find her because it's his class.
One reason could be the shock of the revelation. Harry has always thought his parents were James and Lily. Discovering Snape is his father would be a huge shock, and he might isolate himself to process this new information.