One interesting idea could be Mal's unique powers evolving in a different way under Hades' influence. For example, her magic might take on a darker or more underworld - themed aspect.
Perhaps in this fanfiction, Mal's relationship with the other VKs (Villain Kids) changes. Since she's being raised by Hades, she might have a more conflicted relationship with them, as Hades' teachings could be at odds with their shared experiences on the Isle of the Lost.
One plot idea could be Mal struggling to fit into the Underworld society that Hades rules. Since she's from a different world in Descendants, adapting to the dark and often chaotic nature of the Underworld could be full of challenges and interesting character developments.
Hades himself would be a central character. His influence on Mal, his parenting style, and his own motives for raising Mal would be important aspects of the story.
One idea could be Mal and Chad going on an adventure in a magical forest. They could encounter strange creatures and have to work together to find their way out. Another idea is a story where they attend a ball together and have a romantic dance. They might also get into some comical misunderstandings at the ball.
One common theme is power. Since Hades is a powerful figure and Mal also has her own powers, their interactions often involve power struggles or the sharing of power to achieve a common goal.
One common theme is the exploration of power. Hades is a powerful figure from Greek mythology and Mal has her own unique powers in her fictional universe. Fanfictions often play with how their powers interact and whether they can learn from each other.
There are many great fanfictions about Mal and Hades in Descendants 3. One common theme is exploring their relationship. Some fanfictions might focus on how Mal discovers more about her father, Hades, and how this newfound connection changes her. It could be about her coming to terms with having a rather infamous father and the powers she might inherit from him.
A cool fanfiction could be Mal and Ben swapping powers for a day. This would lead to all sorts of comical and also challenging situations. For instance, Mal would have to deal with the responsibilities of being a king - like making important decisions in court - while having Ben's more 'goody - two - shoes' power. And Ben would be on the Isle of the Lost, trying to use Mal's magic in a place where it's not always welcome. Or a story where they go on a secret adventure away from Auradon, just the two of them, and discover a hidden land that has its own set of rules and magic, and they have to adapt quickly to survive.
You could write a fanfiction where Ben and Mal get transported to an alternate dimension. In this dimension, their roles are reversed. Mal is the one in charge of Auradon and Ben is from the Isle of the Lost. They have to figure out how to get back to their own world while also learning about each other in this new dynamic.
One idea could be exploring Persephone's adjustment to the Underworld. For example, she could start a garden in the gloomy realm using her powers over plants, which not only changes the look of the Underworld but also the attitude of its inhabitants. Another plot could be Hades trying to court Persephone in a more modern way, like taking her on a tour of different parts of the Underworld that are beautiful in their own dark way.
One idea could be exploring the backstories of the minor characters in the House of Hades more deeply. For example, delving into the history of some of the shades that are often just in the background.