Well, perhaps in this fanfiction, the characters from Hazbin Hotel end up in the Naruto world. Charlie could see the problems of the shinobi world, like the discrimination against the jinchuriki, and try to bring her ideas of redemption to the place. Meanwhile, Naruto could befriend the Hazbin characters and learn about their unique powers and backstories, leading to a cross - universe adventure.
A possible plot could be that there's a new threat that affects both the Hazbin Hotel world and the Naruto world. The Akatsuki from Naruto might team up with some of the demons from Hazbin Hotel, either by force or by some sort of deal. Naruto, being the hero he is, along with Charlie and Vaggie from the hotel, have to figure out a way to stop this alliance and save both of their worlds. They would need to combine their different skills, like Naruto's ninjutsu and the magical abilities of the Hazbin characters.
One possible plotline could be Naruto being sent to the Hazbin Hotel universe by some sort of magic or accident. He might then try to use his ninja skills to survive in this new and strange world filled with demons and sinners.
One possible plot could be that the Doom Slayer somehow ends up in the Hazbin Hotel universe. He might initially be seen as a threat due to his violent nature. But then, they realize he could be an asset in dealing with some of the more dangerous demons in the Hazbin Hotel world. For example, he could help Charlie and her crew deal with some of the more unruly and powerful demons that are causing trouble in and around the hotel.
A possible plot could involve Lucifer dealing with the physical and emotional changes that come with pregnancy. This might include her struggling to maintain her usual image of power while also experiencing the more vulnerable aspects of carrying a child. Additionally, it could explore how her relationship with other important characters, like Charlie, is affected as she goes through this new phase.
One possible plot could be that the Doom Slayer somehow gets teleported to the Hazbin Hotel universe. He then has to deal with the demons there, which are different from the ones he usually fights. The hotel staff might initially be afraid of him, but then realize he could be an asset in dealing with more malevolent demons.
Maybe the Hazbin Hotel is in the middle of a crisis where the souls of the damned are being consumed in a strange and new way. Charlie and her crew suspect it has something to do with a portal that has opened up to a dimension filled with the kind of demons the Doom Slayer is used to fighting. They seek out the Doom Slayer, who has to navigate the politics and oddities of Hazbin Hotel's Hell while trying to close the portal and stop the consumption of souls.
Well, one possible plot could be that Alastor discovers a baby in Hell. He might initially be quite perplexed as he's not used to dealing with such an innocent being in the chaotic and sinful environment of Hell. He could decide to take the baby under his 'wing' in his own strange way, perhaps seeing it as an interesting new addition to his world. He might then try to teach the baby about his view of Hell, but also find himself softening a bit as he gets attached to the little one.
One possible plot could be that some of the Hogwarts students accidentally end up in Hell (the setting of Hazbin Hotel). They could encounter the characters from Hazbin Hotel and have to find a way to get back. Maybe they initially think it's a part of some new magical realm or a powerful dark wizard's creation. For example, Harry Potter, Hermione, and Ron could meet Charlie and learn about her plan to rehabilitate sinners. The Hogwarts students might be skeptical at first but then start to see some similarities between the way magic is used in Hell and at Hogwarts.
One unique aspect is the character crossovers. Naruto's ninja abilities and his strong sense of justice are a stark contrast to the morally ambiguous and often sinful characters in Hazbin Hotel. It creates a really interesting dynamic when they interact.
One idea could be Naruto somehow ending up in the Hazbin Hotel universe. Maybe he's on a strange mission and gets transported there. He could use his ninja skills to help the characters in the hotel deal with some of their problems, like fighting off demons that are causing trouble outside the hotel's protection. Another plot could involve the Hazbin Hotel characters visiting Naruto's world and being amazed by the different kind of powers and cultures there.
It also keeps the interest alive during the wait for new official content. When there's a long gap between new episodes or developments in the official Hazbin Hotel story, these fanfictions give fans something to enjoy. They can explore new storylines and ideas that are inspired by the original but still have their own unique twists, like a fanfic where the characters react to a time - travel scenario.