In a fanfiction scenario like this, the mystery man blindfolding Draco could be part of a magical experiment. Perhaps the mystery man is trying to unlock some hidden power within Draco. Since Draco is from the Slytherin house, there could be some dark magic involved. Or, it could be the opposite, and the mystery man is trying to protect Draco from some other dark force by hiding his identity from him. This could lead to a whole new adventure for Draco where he has to trust the mystery man blindly.
Perhaps it's a rival student from another house who's playing a prank on Draco. They blindfold him to lead him into an embarrassing situation, like making him walk into a classroom full of students while looking silly. Or it could be a new character created by the fanfiction author, someone with a mysterious past and a connection to Draco that has yet to be revealed. This new character might be on a quest that involves Draco, and blindfolding him is just the first step in their plan.
Another idea is that Draco becomes involved in some sort of underground magical movement. After Azkaban, he may be disillusioned with the established magical order. He could join a group that aims to reform or even overthrow the current power structures in the wizarding world, leading to all sorts of adventures and conflicts.
Perhaps Snape would force them to work together on a task as punishment. This could be something like cleaning the Potions classroom without magic or helping in the Forbidden Forest. During this time, they might start to understand each other better. Harry could see that Draco isn't just a spoiled brat all the time, and Draco could see that Harry has more depth than he initially thought.
One possibility is that they start arguing at first. Draco, being his usual snarky self, might blame Hermione for getting them into this situation. But as time passes, they could gradually start to understand each other better. They might share some of their deepest fears and secrets, which they would never have done in normal circumstances.
In this fanfiction scenario, Draco joining the Order might also mean a significant change in his relationship with Hermione. They could start to see each other in a whole new light. Their shared experiences within the Order could bring them closer together. Draco might learn more about the Muggle - born rights that Hermione is so passionate about, and this could further his transformation from a pure - blood supremacist to a more open - minded wizard.
Well, perhaps the kidnappers are Death Eaters who have a different plan for Draco. They could be trying to use him as a bargaining chip against his father, Lucius Malfoy. This would put Draco in a really tough situation, caught between his loyalty to his family and his own desire to break free from the dark side that his family is associated with.
She might find love in an unexpected way. Since she's now a man, her romantic interests could shift. She could meet someone who sees her new male self in a way that she never experienced as a woman. For instance, she could fall in love with a woman who is attracted to the qualities she now has as a man.
Well, Draco standing up to his parents could lead to a lot of internal family drama. His parents might be shocked and try to bring him back into the fold. But Draco, being determined, could resist. He might leave his family home and start a new life on his own. He could also use his knowledge of the dark arts that he learned from his family in a more positive way, to fight against the real evil in the wizarding world.
Well, one possibility is that Harry would be completely shocked. He might initially think Draco is playing some sort of cruel joke on him. After all, they've been rivals for so long. But then, he could start to consider it seriously. Maybe he realizes that this could be a chance to bridge the gap between them. He might accept, which would cause a huge stir among their friends and classmates.
Well, if Draco gives Harry a lust potion in fanfiction, it could lead to a lot of chaos. Harry might start having unexpected feelings towards Draco or others around him. His normal behavior would be disrupted as the potion takes over his emotions. He could struggle to control his actions and thoughts, which would create a very interesting dynamic in the story.