What are some interesting ideas for a Black Butler demon OC fanfiction?

One idea could be a fanfiction where Ciel and the demon, instead of their usual master - servant relationship, become allies in a different realm. They could be on a quest to save a parallel world that is being threatened by a powerful dark force. Another idea is a story where the demon has to protect Ciel from a group of rogue demons who see Ciel as a valuable asset due to his connection with the underworld. Maybe in this fanfiction, Ciel discovers a new power within himself that the demon has to help him control.

Another plot could involve an OC who is a powerful magician from a foreign land. They come to England seeking a powerful artifact that Ciel also has his eyes on. This would lead to a series of battles and negotiations between the OC, Ciel, and Sebastian, with the OC having their own set of goals and motives that might not be entirely clear at first.

One idea could be Ciel exploring his new demonic powers. He might start to see the world in a completely different way, with his values shifting as he is no longer bound by human limitations. For example, he could use his powers to seek revenge in a more extreme way than he could as a human.

One idea could be an OC who is a detective from another country coming to London to solve a series of mysterious murders that seem to be linked to the supernatural activities in the Black Butler world. This OC could cross paths with Sebastian and Ciel as they are also investigating the same case from their own motives.

One interesting 'oc black butler fanfiction' could be about an OC who is a detective trying to solve a mystery in the world of Black Butler. They might interact with the main characters like Ciel and Sebastian in unexpected ways.

One plot idea could be that the OC is a new servant in the Phantomhive household. Sebastian initially views her as a nuisance but as they interact more, a strange attraction develops. For example, during a ball at the manor, the OC accidentally spills wine on a noble guest. Sebastian steps in to save the situation and in the process, he realizes her charm and quick - wittedness.

Well, you could do a fanfiction where the cats are actually reincarnated souls from the past. They remember their previous lives and are trying to influence the events in the Black Butler world in a positive way. For example, a cat might be a former noble who was wrongly accused and now wants to help Ciel uncover the truth about a similar situation.

One idea could be that the OC's pregnancy is a result of some dark magic experiment gone wrong in the Black Butler world. And she has to find a way to reverse it while protecting the unborn child. Another is that the baby has some special powers that different factions in the series are after. Maybe the OC is a servant in the Phantomhive household and the pregnancy causes a stir among the other servants.

Well, one interesting concept could be modernizing the Victorian setting. For example, making the Phantomhive manor a high - tech mansion with advanced security systems instead of the old - fashioned one. Another concept might be the modern occupations of the characters. Instead of being a butler in the traditional sense, Sebastian could be a personal assistant with extraordinary skills in a corporate world. Also, modern OC (original character) can bring new dynamics to the story, like a modern detective OC who gets involved with the dark secrets of the Black Butler world.

One plot idea could be that the male OC is a detective hired to investigate strange disappearances in the Black Butler world. He starts to suspect that there's a supernatural force at work and teams up with the main characters to solve the mystery. Another idea is that he's a nobleman's son who has a secret identity as a vigilante, fighting against the corrupt nobles. He might cross paths with Ciel and Sebastian when they're on a mission related to the same nobles.