Yes, there might be some extremely dark and out - of - canon fanfictions out there with such a disturbing premise, but it goes against the general nature of the original story where Harry's parents loved him deeply. However, in the vast world of fanfiction, people can create all kinds of strange and often inappropriate scenarios.
It could be because some fanfiction writers want to take a different approach and create a new storyline where Harry's role or perception is challenged.
One possible reason could be that he might feel abandoned. Growing up without them, he could resent the fact that they left him an orphan. He might think that if they were really so great, they would have found a way to survive and be there for him.
Sometimes, in fanfiction, authors like to challenge the established norms to create unique and unexpected plots. Maybe they thought it would add more depth or drama to have Harry Potter not be the boy who lived in their particular story.
It could be a character whose fate was changed in the fanfiction compared to the original book. Maybe it's a minor character who was supposed to die but didn't.
Perhaps it's to showcase Neville's growth and strength that was often overlooked in the original story. This fanfiction idea might aim to highlight that anyone can rise to the occasion and be a hero, not just the obvious choice like Harry.
Perhaps it's to challenge the traditional narrative and offer a fresh perspective. Maybe it's to show how Ron could have handled the challenges if he were in Harry's shoes.
It's rare. Usually, the 'boy who lived' is Harry Potter himself in the original story and most fanfictions adhere to this. However, there could be unique takes where his brother takes on that role, but it's not the norm.