Perhaps a human arrives in Hell and has some special power that they don't even know about. In the Hazbin Hotel, they slowly discover this power. It could be related to their ability to empathize, which is very different from the demons. This power attracts the attention of both good and bad characters in Hell, and they have to decide how to use it.
One idea could be a human who ended up in Hell due to a deal gone wrong with a demon on Earth. They have to navigate the strange and dangerous world of Hazbin Hotel while trying to find a way to reverse their fate. Maybe they team up with some of the hotel's residents who see an opportunity in their unique situation.
A plot could revolve around a human who was wrongly sent to Hell. In the Hazbin Hotel, they start a sort of revolution among the sinners. They use their human values and beliefs to question the whole system of Hell. They might face opposition from the more powerful demons, but gain support from the more reform - minded characters in the hotel.
One idea could be Adam's backstory exploration. Maybe he had a different life before coming to the Hazbin Hotel universe and that could be delved into. For example, his family, his upbringing, and how those things might have shaped his current self.
One idea could be an OC who is a fallen angel trying to redeem themselves in the Hazbin Hotel. They could face challenges from both the sinners and the hotel staff, adding an interesting dynamic.
One idea could be that God decides to visit the Hazbin Hotel to see if there's any hope for redemption among the demons. He could interact with Charlie and the other characters, causing them to question their beliefs and actions. Another could be a story where God sends an angel to the hotel undercover to observe and report back, and the angel ends up befriending some of the demons, blurring the lines between good and evil.
Well, a plot idea could be that Alastor discovers a new power within himself in the context of a fanfiction. This new power could either help or hinder his standing in Hell. Also, perhaps a plot where Alastor tries to start his own 'radio show' in Hell that's different from his usual broadcasts, and it causes all kinds of uproar among the demons. Or, what if Alastor is forced to team up with someone he really dislikes, like Vox, to face a common threat to their power in Hell?
One idea could be exploring Lucifer's past before the events of Hazbin Hotel. Maybe show his rise to power and the decisions that led him to become the ruler of Hell. Another could be a story where Lucifer has to deal with a new, powerful demon who challenges his authority in Hell. A third idea might be a fanfiction that focuses on Lucifer's relationships with the other main characters in a more in - depth way, like his true feelings towards Charlie and how he views her plan for the hotel.
You could also write a fanfiction about a new character arriving at the Hazbin Hotel. This new character could have a unique power or a very different personality from the existing ones, which would create all sorts of new interactions and storylines. Maybe they have a special ability to see the pasts of the other characters and use that to help them on their path to redemption.
One idea could be exploring the backstories of the characters in more depth. For example, delving into how Alastor became the Radio Demon. Another could be creating a new character who arrives at the hotel and causes a stir among the existing residents. Maybe a character from a different dimension or with a very unique power.
You could write a fanfic about a competition among the demons in the Hazbin Hotel. They could compete in various challenges that test their skills, whether it's singing, dancing, or something more devious. The winner could get a special prize, like a one - day pass to visit the human world or a chance to be upgraded to a better room in the hotel. This would show different sides of the characters and create a lot of interesting interactions.
Vaggie is a character that can add depth to the story. She's protective of Charlie and the hotel's mission. She might be initially suspicious of the human but later come to understand and support them. Alastor is also a key character. His powerful and mysterious nature can either be a great help or a huge obstacle for the human. He might see the human as an interesting experiment in his never - ending search for entertainment in Hell.
In 'human in hazbin hotel fanfiction', one interesting concept is the human's impact on the existing power structures in the Hazbin Hotel. Since the hotel is mainly populated by demons, a human's presence can disrupt the status quo. They might introduce new ideas about forgiveness and second chances that are different from what the demons are used to. For example, they could try to convince some of the more cynical demons that there is a better way than just living in eternal damnation. Also, the human's perception of the afterlife as depicted in the Hazbin Hotel world can be a source of exploration. They might be horrified at first by the idea of sinners being punished in such extreme ways, and this could drive their actions to try and change things. And the human could also be a catalyst for character development among the demons, as they interact and learn from each other.