Another plot point could be the reaction of the people around them. The male lead may have enemies or rivals who try to use the presence of the adopted daughter against him. Or there could be other family members who are jealous of the attention she gets from the male lead. This can create a lot of drama and conflict in the story, forcing the female lead to prove herself worthy of being in the family and also protecting the male lead in return.
Perhaps the story involves the female lead using her new position as the male lead's adopted daughter to change the fate of the family or the world around them. She could have some knowledge from her previous life (if it's that type of story) and tries to prevent disasters or improve the family's standing in society. Like, she might know about a business deal that will go wrong and uses her influence as the daughter to stop it.
One common theme is family. Since the female lead becomes the male lead's adopted daughter, there is a focus on building a new family dynamic. It could be about learning to trust and love within this new family structure.
One popular 'I became the male lead's adopted daughter' novel is 'The Adopted Daughter of the Male Lead'. It has an interesting plot where the female lead, after becoming the adopted daughter, changes the fate of the male lead and those around them in a fantasy world.
The female lead's character development might start with her being in a vulnerable state when she first becomes the adopted daughter. As she adapts to her new life, she becomes more confident. For example, if she was initially shy, living with the male lead and being part of a new family gives her opportunities to grow and speak up for herself.
Well, a plot point could be how Harry's presence affects the Malfoy family's reputation in the wizarding world. Some might see it as a sign of the Malfoys changing their ways. In the fanfiction, Harry might also discover secrets about the Malfoy family that they've been hiding for generations. And of course, there's the whole aspect of how Harry's magical abilities develop in this new environment. He could learn different spells or techniques from the Malfoys that he wouldn't have otherwise.
One interesting plot point could be how Harry adapts to the Malfoy family's pure - blood traditions. He might struggle with their values at first. For example, the Malfoys' view on blood purity and how that contrasts with Harry's more inclusive nature.
One interesting plot point could be how Izuku adjusts to living with Midnight. He might learn new ways of using his quirk under her guidance. Another could be the relationship dynamics that develop between Izuku and Midnight's friends or colleagues in the hero world.
One interesting plot point could be how Harry and Malfoy adjust to their new family dynamic. Malfoy, coming from a very different background, might struggle with the more humble and kind - hearted values that Harry represents. Another could be how the wizarding world reacts to this unexpected adoption. Some might be shocked or even disapproving, thinking that a former enemy should not be taken in so readily.
One plot idea could be the adopted daughter discovers she has a unique power. Maybe she can communicate with animals like Batman can with bats. This new power causes some chaos as she tries to figure it out and also keep it a secret from Batman at first. Another idea is that she gets into trouble at school because of her association with Batman. Bullies target her, but she uses her martial arts training (that Batman taught her) to defend herself in a really cool way.
One common theme is redemption. Often, the male lead has some past mistakes or a troubled past, and taking in the adopted daughter becomes a way for him to find redemption. For example, he might have been a cold - hearted person before, but the love and responsibility towards the daughter change him.
Well, perhaps the story focuses on how the adopted Malfoy copes with the expectations that come with the Malfoy name while also trying to form their own identity. It could involve them making friends outside of the typical Malfoy social circle, which would create all sorts of interesting interactions and conflicts.