One idea could be the demon's mate having a special power that is the key to saving the demon realm from an ancient curse. Another could be the struggle of the mate to adapt to the demon's dark and dangerous world while still holding onto their own humanity. Maybe the demon's mate is from a different supernatural species, like an angel, and their relationship is a forbidden love that defies the rules of both their worlds.
Well, perhaps the plot could involve the demon's mate being hunted by other demons who are jealous of their relationship. The two of them then have to go on a journey to find a powerful artifact that can protect them. Or, the mate could be a human who discovers a hidden family connection to the demon world, and through that connection, they meet their demon mate and together they uncover secrets about their families that were long buried.
One idea could be the protagonist discovers a hidden power within themselves while being held captive by the demons. This power could be the key to their escape or a way to turn the demons' own plans against them.
One idea could be a new character coming into the Phantomhive household as a potential mate for Sebastian. This character could be a half - demon with unique powers and a mysterious past. Their presence would disrupt the usual dynamic between Sebastian and Ciel, creating all sorts of interesting conflicts and power struggles.
Well, perhaps Hermione and Klaus meet in a dream - like state first, as a premonition of their mate bond. When they finally meet in person, there is an instant attraction and connection. But Hermione is hesitant because of Klaus's reputation. So, Klaus has to prove himself worthy of her. They could then embark on a journey to break a curse that is related to their mate bond, facing various challenges along the way, like dark magic and ancient creatures.
A possible plot for Harry and Tom mate fanfiction is that they are both sent on a special mission by Dumbledore. Along the way, they have to rely on each other's strengths. Tom might use his intelligence and cunning, while Harry uses his courage and loyalty. They could also encounter magical creatures that they have to work together to defeat. This would force them to put aside their differences and form a bond. And as they complete the mission, they realize that they can learn a lot from each other.
Perhaps in the fanfiction, there's a mysterious illness spreading in the village that only affects ninja with strong bonds to their animals. Kiba is worried about Akamaru, and Naruto offers to help find a cure. They travel to different lands, meet various healers, and during this journey, they learn more about each other's pasts and dreams, forging a deeper connection.
One idea could be that Harry discovers a magical realm where Jareth rules and they initially clash due to their different personalities. But as they face common threats, like a dark force trying to invade both their worlds, they start to understand each other and form a bond. Another could be a story where Harry is transported to Jareth's world and has to learn the rules there to survive, and Jareth takes an interest in him because of his unique magic from the wizarding world.
One idea could be that the OC is a mutant with a unique power that complements Wolverine's abilities. For example, the OC can manipulate time briefly, which helps Wolverine in a crucial battle. They meet when Wolverine is on a solo mission in a remote area and the OC is being hunted by anti - mutant forces.
A plot could revolve around a new villain emerging from the Land of Demons. This villain has a special connection to Naruto's past, and Naruto must face his own inner demons as well as the external threat to save the Land of Demons and his own world. The story could explore themes of redemption and self - discovery.
One idea could be an OC who is a half - angel, half - demon and is on a quest to find their true identity. They struggle between the good and evil tendencies within them.
Another plot idea could be them dealing with a new threat together while also trying to balance their relationship. Vegeta might be more focused on protecting Bulma and the planet, while Bulma uses her intelligence to come up with strategies. They could grow closer through these shared experiences.