Maybe their child gets sent back in time to when Adrien and Marinette were still just friends and classmates. The child then has to figure out a way to get back to their own time without changing the past too much. They might accidentally cause some comical misunderstandings between their parents - to - be in the process.
Another plot could be that their child is a target of a new villain in Paris. This villain wants to use the child's connection to Ladybug and Chat Noir to gain power. So, Adrien and Marinette have to not only protect their child but also keep their identities a secret from the public while doing so. This would put a lot of strain on their family but also show their strong bond as a family unit.
A possible plot is that Adrien is akumatized after his father is extremely harsh on him for not following the family's strict rules. His akuma form, 'Rebel Son', might have a look that combines his Chat Noir features with a more rebellious and angry look. Marinette could be akumatized when she's framed for something she didn't do at school. Her akuma form, 'Innocent Victim', would have a look of someone who has been wronged and is out for revenge.
One idea could be that they face challenges in their superhero lives while being pregnant. For example, they have to keep their identities secret even more carefully to protect their unborn child. Another could be that they discover new powers related to the pregnancy, like a connection between the baby and the Miraculous.
One plot idea could be that they discover they're pregnant unexpectedly. Maybe they're still in high school and have to deal with the reactions of their friends and family. Their friends could be initially shocked but then become very supportive. Another idea is that an akuma attack somehow affects the pregnancy, adding a layer of danger and drama.
One idea could be that they are modeling for a high - fashion charity event. Marinette is nervous at first but Adrien's calm presence helps her relax. As they pose together, they start to realize their feelings for each other are growing deeper. They share some cute glances and little inside jokes during the photo shoot, which makes the pictures turn out even more amazing.
One great plot idea could be a story where Marinette and Adrien are paired up for a school project that requires them to travel to a different city. This would force them to spend a lot of time together outside of their usual Parisian setting. They could discover new things about each other and grow closer. Another idea is a fanfiction set in a future time where they have both retired as superheroes. They start to reminisce about their past adventures and realize how much they've been through together, which reignites their feelings in a more mature way. And a third idea could be a story where they get trapped in an alternate dimension. There, they have to rely solely on each other to find a way back home, which deepens their bond.
One idea could be that Adrien initially feels shocked but also a sense of relief. He might have always had a feeling that Marinette was special, and now it all makes sense. So he starts to view her in a whole new light, with more respect and admiration for her dual identity.
Well, a plot could revolve around Adrien being akumatized when he discovers a dark secret about his mother. This could lead to his akumatized form having powers related to uncovering hidden truths and punishing those who have been lying. Or perhaps he's akumatized because he's tired of being in the shadow of Chat Noir. His akumatized self then tries to prove that Adrien is just as important as his superhero alter - ego. Also, he could be akumatized due to a betrayal from a friend, and his akumatized form focuses on isolating that friend from everyone else.
Maybe there's a plot twist where one of them loses their memory due to an akuma's power during the pregnancy. This forces the other to try and make the失忆的一方 remember their relationship and the impending baby. It can create a lot of heart - wrenching moments.
One interesting plot twist could be that the jealous kiss was misinterpreted by a third party, like Alya, who then spreads a false rumor about Adrien and Marinette being in a secret relationship. This causes chaos as they both have to deal with the unwanted attention and also their own confused feelings. Another plot twist might be that the jealous kiss unlocks a hidden memory for one of them, perhaps Marinette remembering a past life where she and Adrien were lovers, which adds a whole new layer of complexity to their current relationship.
It could also be about the challenges they face during the pregnancy. Marinette might have health issues, and Adrien has to be extra careful and supportive. There could be a lot of emotional turmoil as they both grow up faster than they expected. They might also face some judgment from society, but they stand strong together to face it all.