Perhaps Draco's actions during a war or a major conflict in the fanfiction world led to his death sentence. He might have made a decision that cost many lives, even if it was a difficult situation and he was acting under duress. His family's reputation as former Death Eaters wouldn't help his case either, and the public outcry for justice could push for the harshest punishment.
One way it could develop is through Draco getting involved in a dark magic plot gone wrong. Maybe he was forced to participate by the Death Eaters in his family, and when things got out of hand, the wizarding world decided on a death sentence for him. In some fanfictions, the political climate in the wizarding world might be so strict that any association with dark magic at that level is seen as unpardonable.
Well, it could be that Draco is forced to follow the Death Eater path while Hermione is fighting against them. But then, they might get thrown into some situations together, like being trapped in a place. Draco realizes that Hermione is not just a Mudblood in the sense that he was taught, and they start to form an unlikely bond. Their relationship could be full of tension, with Hermione constantly trying to convert Draco or at least make him see the wrong in what he's doing, and Draco struggling between his loyalty to his family's Death Eater ideals and his growing feelings for Hermione.
Hermione would likely be more analytical. She might start researching the legal aspects of the case, looking for loopholes or signs of a miscarriage of justice. She would be outraged if she thought Draco was being wrongly accused, as she values fairness and the rule of law in the wizarding world.
One way this could develop is that Hermione's sacrifice could be a turning point in Draco's character. He might have been on a dark path before, but her selfless act makes him question his beliefs and actions. He could then start to work towards redemption, perhaps trying to fight against the dark forces in honor of Hermione.
One way it could develop is through the use of dark magic coercion. Maybe a powerful Death Eater discovers Hermione's intelligence and decides to use Imperius Curse to make her his slave. He could force her to use her magic skills for his evil purposes, like brewing dangerous potions or stealing valuable magical artifacts.
One way this could develop is that Voldemort sees an opportunity to use Hermione's intelligence for his own gain through this union. He might think that by having Draco marry Hermione, he can control the magical knowledge she has. Draco, on the other hand, might initially resist as he has his own pure - blood ideals. But under Voldemort's pressure, he could be forced into it. Hermione would surely fight against it, using her wits and the support of her friends like Harry and Ron to find a way out of this strange and unwanted situation.
It could be about Draco being in a situation where he's somehow sentenced to a kiss. Maybe it's a part of a magical punishment or some sort of bet in the wizarding world of the fanfiction's setting. It might involve his relationships with other characters, like his enemies or love interests.
Well, it could mean that in a fanfiction context, the character Draco is given some sort of punishment or situation within the fan - created story. Maybe he's been condemned to a particular fate, like being exiled or having to perform certain tasks as part of the plot in someone's fanfiction.
The plot could develop in a very dark way. Harry might start hunting down the Order of the Phoenix members. He would be using his knowledge of the good side to help the Death Eaters. For example, he could lead them to the secret passages in Hogwarts.
The development might also involve the Death Eater introducing Hermione to some secrets of the Death Eater organization in a bid to undermine it from within. This would be a very risky move. Hermione, being the clever witch she is, would have to be very cautious in dealing with this new - found ally. She would need to constantly assess whether his help is genuine or part of a bigger trap. Their relationship would be full of tension and mutual suspicion at the start, but gradually they could learn to trust each other more as they work towards a common goal, like bringing down Voldemort's regime.
One way this plot could develop is through a political or family power play. In the wizarding world, marriages are sometimes used to strengthen alliances. Maybe the Malfoy family and some powerful wizarding families or political forces force the situation. Harry, being female in this fanfic, might initially resist but then gradually find some unexpected common ground with Draco as she gets to know him better in this forced situation.