The relationship with Adrien is a huge theme. It could be about how they navigate their relationship when this big change occurs. Some fanfictions show them having to grow up quickly and become more responsible for each other and the baby. It also might explore how their identities as Ladybug and Chat Noir play into their new family situation.
One common theme is the exploration of their unrequited love. In the show, Marinette has a crush on Adrien, but in fanfictions with Luka, she may start to realize her feelings for him. Another theme is the power of music. Since Luka is associated with music, it often plays a role in bringing them closer, like Luka writing a song for Marinette.
One common theme is the exploration of unrequited love. Sometimes Marinette is still pining for Adrien while Luka is there loving her silently. Another theme is the power of music in their relationship, as Luka is a musician. It often serves as a bond between them.
One common theme could be Marinette's struggle with her anger in relation to her love for Adrien. Maybe she gets angry when she sees him with other girls out of jealousy. Another theme might be her anger towards Hawk Moth and his villains, as she tries to protect Paris in her Ladybug form. Also, it could explore how her anger affects her friendships, like with Alya, when she's too frustrated to confide in her.
One common theme is the 'will - they - won't - they' situation. Since Marinette is so shy and Adrien is a bit clueless about her feelings, a lot of fanfics play around with this dynamic.
A common opponent is Chloe when she gets akumatized. In fanfiction, their battles can be more intense and personal. Marinette, as Ladybug, has to deal with Chloe's over - the - top attacks and her mean - spirited nature while trying to purify the akuma.
A really interesting fanfiction idea could be that Lila and Marinette switch personalities for a day. This would be a comical yet thought - provoking situation. Lila would have to deal with Marinette's responsibilities and kindness, while Marinette might struggle with Lila's devious ways. It could lead to both of them having a new perspective on each other.
One possible fanfiction could be about Marinette's daily life with Tikki. For example, Marinette could be having a tough day at school, getting bullied by Chloe. Tikki, being her kwami, tries to cheer her up by suggesting they make some special macarons. They then spend the evening in Marinette's room, sharing stories and laughing, which helps Marinette forget about her bad day.
Well, this kind of fanfiction could start with Marinette making a mistake while using the Miraculous. Then she finds herself in the form of a Kwami. She might be really tiny and have to find ways to get around. She could hitch rides on people's shoulders or use her small size to her advantage when it comes to spying on Hawk Moth. And she would definitely have to deal with the fact that she can't just transform back into her normal self right away, leading to all sorts of comical and tense situations.
There are many interesting fanfictions about Marinette and Luka. Some might focus on their relationship development outside of the superhero chaos. For example, a fanfiction could explore how they go on a simple date, sharing their interests like Marinette's fashion design and Luka's music.
One possible fanfiction could be about Marinette using her flexibility in a new way to design fashion. For example, she might create a line of clothing that is both stylish and allows for maximum movement, inspired by her own experiences as Ladybug. She could hold a fashion show where models are shown doing acrobatic stunts while wearing her designs, highlighting the flexibility aspect of the clothes.