Yes, there might be. There are countless fanfictions out there in the vast world of Harry Potter fan creations. However, the 'King of Hell' concept is likely a very unique and perhaps a darker, more alternative take on the Harry Potter universe. You can try searching on popular fanfiction websites like Fanfiction.net or Archive of Our Own.
There might be fanfics that focus on the backstories of minor characters. In 'hell harry potter fanfic', perhaps there are stories about the life of a house - elf we barely knew in the original books, like Dobby's early years at the Malfoy Manor.
Well, in this 'Harry Potter is King of Hell' fanfiction, it could potentially explore a dark and alternate universe. Maybe Harry, after all his battles in the wizarding world, somehow ends up in hell and through his strength and wits, rises to be its king. It could also involve his encounters with the various demons and creatures of hell, and how his Hogwarts - learned magic works in that completely different environment.
In many Harry Potter fanfictions, Daphne Greengrass might be portrayed as a Slytherin student with her own unique traits and storylines. Sometimes she's a friend, sometimes an adversary, or even a love interest, depending on the author's imagination.
Another way is to follow authors who are known for writing great 'Harry Potter' fanfics. If you find an author whose work you really enjoy in 'hell harry potter fanfic', chances are their other works will also be good. They often have a consistent writing style and quality that you can rely on.
Another theme is the exploration of power. In Harry Potter, power comes in the form of magic, while in Hell Girl, it's more about the power to condemn souls to hell. Fanfictions may show characters from Harry Potter being tempted by Hell Girl's power or trying to understand it in the context of their own world.
Harry Potter is the central figure in this fanfiction. However, we may also see characters from the hellish realm introduced. There could be powerful demons or other supernatural beings that interact with Harry. Maybe there are some original characters created just for this fanfiction who play important roles in Harry's journey as the king of hell, like a trusted advisor or a fierce enemy.
I think 'Harry Potter Hell Spawn Fanfiction' might be centered around a very particular subset of fan - created stories. It could be that some fans are exploring the darker aspects of the Harry Potter world, like what would happen if Voldemort had managed to create some sort of unholy abomination. It could also be about exploring the afterlife in the Harry Potter universe in a very dark and untraditional way, perhaps with 'hell spawn' - like entities emerging from the depths of some dark magical realm.
It could be about a very unique and wild crossover. Maybe it involves Harry Potter characters interacting with archangels in a hell - like setting. It might explore how the magic of the Harry Potter world combines with the celestial and infernal elements of archangels and the concept of hell.