Well, a possible plot twist is that Hermione and Draco find out their baby has a unique magical gift that is both a blessing and a danger. For example, the baby could have the power to control time, which attracts the wrong kind of attention from dark wizards who want to use the baby's power for evil. Also, there could be a twist where Hermione's pregnancy makes her lose some of her magical abilities temporarily, and she has to rely on Draco more than she expected, which changes the dynamic of their relationship.
One interesting plot twist could be that Draco's family initially opposes the relationship but then comes around when they see how much he loves Hermione. Another could be that Hermione discovers a new magical ability during her pregnancy that has never been seen before. Maybe it's related to the combination of her and Draco's magic. A third plot twist might be that there is a threat to their unborn child from an old enemy of either the Malfoys or Hermione's friends, forcing them to team up with unexpected allies to protect their family.
One popular plot twist could be that they keep their relationship a secret from their former Hogwarts friends at first. Their different backgrounds and the history of enmity between Gryffindor and Slytherin make it a big deal. Another could be that there's a prophecy involved that ties their unborn child to some great destiny in the wizarding world. Maybe the child is predicted to bridge the gap between the pure - bloods and the Muggle - borns, which adds a whole new layer of drama to the story.
A possible plot twist is that Hermione is actually on a secret mission for the Order of the Phoenix when she marries Draco. She's using the marriage as a cover to get closer to some dark wizards Draco has connections with. As they spend more time together in their 'fake' marriage, they start to truly fall for each other, which complicates things for Hermione's mission.
One interesting plot twist could be that Draco saves Hermione not out of pure altruism but because he discovers a dark plot against the wizarding world that Hermione unknowingly holds the key to solving. So, by saving her, he's also saving himself and his family from a greater threat.
One interesting plot twist could be that Ginny and Draco's pregnancy is a result of a magical accident. Maybe a spell gone wrong during a battle or an experiment that binds their magical essences together. Another could be that they keep the pregnancy a secret from everyone at first, and as they struggle to come to terms with it, they start to develop unexpected feelings for each other. For example, Draco, who has always been a bit of a snob, realizes Ginny's true strength and kindness through this situation. And Ginny sees a more vulnerable side of Draco that she didn't expect.
One interesting plot twist could be that they are betrothed due to a magical contract made by their ancestors to end an old feud between the Gryffindors and Slytherins. Hermione at first resists but then discovers Draco has a kinder side she never knew. Another could be that in the middle of their betrothal, a dark wizard tries to use their union for his own evil purposes, forcing them to work together to stop him. And perhaps, after all the chaos, they realize they actually love each other in a way they never expected.
A possible plot twist could be that Hermione gets turned into a Death Eater against her will, and Draco has to help her break free from the dark magic controlling her. This would completely reverse their typical roles.
In some fanfictions, there could be a time - travel plot where Draco and Hermione from different timelines end up together and Hermione gets pregnant. This would involve dealing with the consequences of changing the timeline as well as their relationship dynamics.
In a post - war wizarding world, there is a new potion that has some unexpected side effects. Draco and Hermione accidentally consume it. As a result, Hermione becomes pregnant. They are both shocked and confused. But as they navigate through this strange situation, they find that they have more in common than they thought. They start to bond over their shared experiences in the war and their hopes for the future of their child.
One possible plot twist could be that the tie - switching is part of a magical prank gone wrong. Maybe Hermione and Draco accidentally swap more than just their ties in a spell - mishap. This could lead to them experiencing each other's daily problems at Hogwarts. For example, Draco might have to deal with Hermione's heavy class schedule and the pressure from her friends to always be the top student, while Hermione has to face the Slytherin's snide remarks towards her as she now looks like one of them.
One plot twist could be that Snape is actually under a spell that makes him fall in love with Hermione. This could lead to a whole mystery about who cast the spell and why. Hermione would then have to figure out whether the love is real or not, while still dealing with the feelings she has developed for Snape. Another could be that they get married in secret, and when it's revealed, it causes an uproar in the wizarding community, with people taking sides either for or against their union.