It could be a fantasy fanfic where Harry discovers a special power or spell that enables him to defeat the Jersey Demon.
I'm not sure about a specific fanfic where Harry kills the Jersey Devil. You might have to search through various fanfiction platforms or communities to find one.
It could be in a dark alternate universe fanfic where Harry is driven to extreme actions due to unforeseen circumstances.
It could be in a fanfic where Harry teams up with someone powerful or uses a clever strategy that no one expected. The story could also change the nature of the task or the dragon itself to make it possible for Harry to succeed early on.
It's a rather strange and untrue statement. 'Harry Potter' is a well - known and beloved fantasy series, not a 'demon fanfic'. Fanfic usually refers to fan - created fiction, but this description completely misrepresents the essence of the Harry Potter world which is about magic, friendship, and the battle between good and evil in a fictional magical universe.
It could be an entirely new type of dragon created specifically for this fanfiction. The author might have wanted to introduce a unique dragon with special abilities, like a dragon that can change its color to blend in with its surroundings or one that can breathe not just fire but also some kind of magical ice. Harry would then have an even greater challenge when trying to kill it with the sword.
It could be in a self-defense situation when the basilisk poses an immediate threat to him or his friends in Hogsmeade.
It might be a fanfic that explores Harry's inner conflict as he serves Saron against his will, perhaps due to a threat to his loved ones.
It could be a magical fantasy fanfic where Harry's vision reveals a hidden secret or a future event that sets off an adventure.
It could be a story where Harry faces tough subjects or has a hard time understanding the teaching methods, resulting in him performing poorly at school. Also, there might be some personal issues affecting his concentration and academic performance.
Maybe it's a story where Harry is distracted by personal problems and can't focus on his studies, resulting in poor grades.