There are fanfictions where in Diabolik Lovers, the female lead is not as submissive as in the original and stands up to the male vampires in a more assertive way. For Fairy Tail, some fanfictions focus on the backstories of minor characters like Levy and how she discovers a powerful ancient magic. A Diabolik Lovers and Fairy Tail crossover fanfiction might involve the Fairy Tail mages trying to understand the complex relationships among the vampires in Diabolik Lovers.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of both Diabolik Lovers and Fairy Tail fanfictions. There are different categories and tags that can help you find exactly what you're looking for. You can search by genre, character, or specific plot elements.
Another idea for a fanfiction is a story that delves into the little brother's past. Maybe he has some hidden memories or a special power that he is unaware of. As the story progresses, he starts to discover these things and it changes his relationship with his family and the other characters. This could create a lot of drama and intrigue as the other characters react to the changes in him.
There might be a fanfiction where Yui gets lost in a strange part of the vampire realm and Subaru is the only one who can find her. He battles his own inner demons as well as the external threats to rescue her. This story would show Subaru's protective side towards Yui.
In some fanfictions, Yui might form an unexpected alliance with a vampire who has been an outcast among the others. This vampire could teach Yui more about their kind, and together they try to change the power dynamics within the vampire household. They might start by uncovering secrets about the origins of the vampires' thirst for Yui's blood, which could lead to a new understanding and a different kind of relationship between Yui and the vampires.
One interesting story could be where the reader is a new student at the school in the 'Diabolik Lovers' world and catches the attention of all the vampire brothers in different ways. Maybe one is initially hostile while another is overly curious.
One idea could be a crossover with Vampire Knight. The Diabolik Lovers vampires could interact with the ones from Vampire Knight in a school setting. There could be rivalries over territory or a common prey. Another idea is a crossover with Black Butler. Sebastian could be hired to deal with the unruly Diabolik Lovers vampires, creating a lot of tense and interesting scenarios. A third idea might be a crossover with Ouran High School Host Club. The vampires could accidentally end up at the host club and chaos would ensue as they interact with the flamboyant hosts.
A friendship - centered fanfiction would be cool. Maybe a new character befriends the vampires not out of fear but because they see the good in them. This character could slowly break down the walls the vampires have built around themselves and change their relationships with each other.
The plot twists are also a big draw. In 'diabolik lovers new stories', just when you think you know what's going to happen, something unexpected occurs. It keeps the story exciting and unpredictable.
Another interesting plot could be that Yui gets sick, and Subaru is the only one who can take care of her. He has to overcome his own insecurities and fears to be there for her. He might learn more about himself and his feelings for Yui during this time. As he nurses her back to health, their relationship deepens in a more tender and emotional way.
A male OC could be a foreign vampire who comes to the setting of Diabolik Lovers with different cultural vampire traditions. This would create interesting interactions as he clashes or blends with the existing vampire families. He could introduce new forms of magic or ways of feeding that are unknown to the others. Maybe he has a more refined and old - world charm compared to the somewhat wilder vampires in the story already. Also, you could have an OC who was once a priest but was turned into a vampire and now battles with his religious past and his vampiric urges.