Perhaps Moody has a vendetta against the Malfoy family and decides to use Draco as a way to get back at them. This could lead to a lot of psychological and physical harm to Draco as Moody uses his skills and knowledge to torment him. It could also involve Draco trying to fight back or find a way to escape Moody's clutches.
I'm not sure about a specific Moody Hurts Draco fanfiction off the top of my head. But you can try searching on popular fanfiction websites like Archive of Our Own. They have a wide range of fanfictions and you might find one with that theme there.
Another interesting plot is when they are both part of a magical competition. They start as rivals but end up learning from each other. In one particular fanfiction, they are in a dueling tournament. Through the duels and the preparation for them, they see each other in a new light and form an unexpected bond.
Well, in some 'Draco turned into a ferret fanfiction', there could be a plot where Draco in ferret form discovers new things about the Hogwarts grounds that he never noticed as a human. Maybe he stumbles upon a secret passage or a hidden magical creature. Also, there could be a story where his transformation is a result of a misfired spell by a student, and the whole school has to figure out how to reverse it.
A third plotline could be Draco's struggle with his identity. He has the memories of his previous life, but he's now in Draco's body. He has to deal with Draco's family expectations, his reputation at Hogwarts, and at the same time, he wants to do things differently. This internal conflict could lead to a lot of character development and new story arcs.
One interesting plotline could be that they discover their twin relationship early on and try to keep it a secret from everyone at Hogwarts. They might secretly help each other out in classes and with their rivalries against other houses.
One interesting plotline could be Draco trying to adapt to Muggle technology. For example, he might struggle with using a mobile phone at first, which could lead to some comical situations as he accidentally calls the wrong people or activates functions he doesn't understand. Another plotline could be his interaction with Muggle schools. He might be shocked by the different teaching methods and lack of magic in the curriculum. Also, a potential plotline could involve Draco making Muggle friends and learning about their values, which could be a huge contrast to what he's used to in the wizarding world.
One possible plotline could be Draco and Hermione being forced to work together on a difficult school project. Despite their initial animosity, they gradually come to respect each other's intelligence and skills. Another could be a situation where they are both in danger and have to rely on each other for survival. This forces them to set aside their differences. And a third could be a magical accident that causes them to swap personalities or abilities, leading to some humorous and also relationship - building moments.
Well, perhaps there's a plot where they are both entered into a magical tournament against their will. In the process of competing, they realize they have more in common than they thought. For example, they both have a strong desire to prove themselves. This shared feeling makes them bond and slowly become friends, or even more, in the fanfiction world.
A great plotline might involve a magical competition where Draco, Blaise, and Harry are all forced to compete. As they face various challenges, they start to understand each other better. For example, they realize that they all have the same fears about the future of the wizarding world. It could also be a plotline where they are all transported to an alternate dimension and have to rely on each other to get back home.
One interesting plotline could be Harry and Draco being deaged and having to rely on each other in a world that seems new to them again. They might form an unexpected friendship as they don't have the pre - conceived notions from their older selves. For example, they could team up to solve a mystery in Hogwarts that only they, with their combined knowledge from before, can figure out.