One possible storyline could be that Ivan writes a song for Mylene. He pours his heart into the lyrics, expressing his deep love for her. Mylene, in turn, is touched and decides to perform a dance to go along with the song for a school talent show. Their performance not only showcases their love but also brings the whole school together in a celebration of art and love.
Maybe there's a storyline where Ivan and Mylene get into an argument. It could be over something as simple as what movie to watch. But this small argument makes them realize how much they mean to each other. They then make up in a really cute way, like Ivan bringing Mylene her favorite flower and Mylene making Ivan his favorite cookies.
Another storyline could be that they both discover a hidden part of Paris together. It's an old, abandoned theater. They decide to clean it up and turn it into a secret place for them. They decorate it with things that are important to both of them, like Ivan's guitar picks and Mylene's old theater playbills. As they work on this project, their relationship grows even stronger.
Ivan might use his size to intimidate the bullies. He stands up to them, his broad shoulders and strong frame making him look imposing. Mylene, on the other hand, uses her wits. She outsmarts the bullies by coming up with clever comebacks that leave them speechless.
One idea could be a story where Mylene uses her acting skills to help Ladybug and Chat Noir in a different way. Maybe she pretends to be a decoy to draw out an akumatized villain. It could show her courage and her ability to think on her feet.
One possible storyline could be that Ladybug sacrifices herself to save Paris from an ultimate villain. Maybe the villain has created a weapon that can destroy the entire city, and Ladybug uses her powers to contain the blast at the cost of her own life. Her death would then lead to a city in mourning and Chat Noir having to step up in a whole new way, trying to keep Paris safe without his partner while also dealing with his grief.
In fanfiction, Mylene's relationship with Ivan is also a significant aspect. Their relationship can be explored further, like how they support each other during difficult times. It could be shown how Ivan's strength complements Mylene's more delicate nature, and vice versa.
One possible storyline could be that Ladybug and Cat Noir have to protect a powerful Tibetan artifact from Hawk Moth. The artifact might have some sort of special power that Hawk Moth wants to use for evil. Another idea is that they encounter new kwamis in Tibet that are unique to the region and have to learn how to work with them. Maybe there are also local heroes in Tibet who team up with Ladybug and Cat Noir to fight against the villains.
One possible storyline could be that Ladybug discovers she's pregnant while still in the middle of fighting akumas. She has to keep it a secret from most people, especially Hawk Moth, as she fears he might use it against her. She might struggle with how to balance her superhero duties and her pregnancy, like finding new ways to move and fight without putting the baby at risk.
One interesting storyline could be Bunnix traveling back in time to prevent an akuma from ever being created. She could team up with Ladybug and Chat Noir in a different time period, leading to a whole new dynamic between the heroes.
In some fanfictions, there are storylines where new Miraculous holders from different parts of the world join the fight. These new characters bring in unique powers and cultures, adding more depth to the Miraculous universe. For example, a holder from an Asian country with a Miraculous related to an ancient mythical creature.
One interesting storyline could be an alternate universe where Marinette and Adrien have different Miraculous powers. For example, Marinette might get the Cat Miraculous and Adrien the Ladybug Miraculous. This would completely change their dynamic and how they fight against Hawkmoth.
One popular storyline could be Marinette having a dream about her future with Adrien while in her bed. In the fanfiction, she might see them getting married and living happily ever after. Another could be Chat Noir secretly visiting Ladybug while she's resting in bed and leaving her a small gift as a token of his affection without her knowing it was him right away.