Perhaps Hermione discovers a new form of magic during her pregnancy. Since she is so brilliant, this new magic could be related to protecting the unborn child. And Antonin could be the one who encourages her to explore this new magic, which in turn deepens their relationship.
One possible fanfiction could be that Hermione and Antonin find themselves in an unexpected situation where they are about to become parents. Maybe it starts with an accidental magic incident that binds them in some way and leads to the pregnancy. It could explore how Hermione, with her strong will and intelligence, deals with the situation while also having to face the reactions of her friends and the wizarding community who might not be so accepting of her relationship with Antonin.
Well, it could be that in a post - war scenario, Hermione is involved in some sort of rehabilitation program for former Death Eaters, and Antonin is one of the participants. Hermione is assigned to help Antonin reintegrate into the wizarding society. As they spend time together, they realize they have more in common than they thought. Their relationship develops, and they have a baby. The story could then focus on how they raise the baby in a world that is still somewhat divided between those who were on different sides of the war.
In this fanfiction, the pregnancy could be a result of a magical accident. Hermione and Blaise are working on a powerful spell, and something goes wrong. Now they have to deal with the consequences. Hermione might be scared but also determined to face it. Blaise would need to step up and support her. They might have to go on a journey to find a way to reverse the spell if they don't want the pregnancy, or they could accept it and start building a family. Along the way, they would face many obstacles, like other wizards who might want to use the situation for their own gain.
One possible plot could be the initial resistance from Hermione. Given her strong will and her loyalty to her friends in the original story, she might be very against this marriage law. For example, she could try to find loopholes in the law. Antonin, on the other hand, might be more accepting as it could be a way to gain power or status. Maybe at first, they are constantly at odds, but as time goes on, they start to understand each other's perspectives and develop an unexpected bond.
It could be that in the fanfiction world, Hermione was the victim of a spell gone wrong. This spell could have made her pregnant and also somehow cut her off from her usual support system, leaving her alone. Or perhaps she made a choice to distance herself from others because she didn't want to endanger them while she was dealing with this unexpected pregnancy.
One possible plot twist could be that Hermione uses her intelligence to outwit Dolohov even while kidnapped. Maybe she manages to leave hidden clues for her friends to find her. Another could be that Dolohov has an ulterior motive other than harming her, like using her as a bargaining chip in the wizarding war. Or perhaps Hermione discovers a hidden power within herself during the time of her captivity that helps her escape.
The exploration of redemption can also be important. Antonin might be on a path of self - discovery and change influenced by Hermione. Their relationship then becomes a vehicle for his possible redemption in the story.
One common theme is the clash of different ideologies. Antonin is often associated with more 'dark' or traditional wizarding ideas, while Hermione is a strong advocate for equality and knowledge. Another theme is redemption. Sometimes Antonin is shown as being redeemed through his relationship with Hermione. And of course, there's the theme of forbidden love, as their relationship would likely be frowned upon in the wizarding world.
There could be a situation where Draco has a change of heart later. Maybe he realizes his mistake after some time away and tries to come back into Hermione's life. This could lead to a very emotional and complex reunion, with Hermione having to decide whether to forgive him or not.
One way this could happen in fanfiction is if there was some form of time - travel involved. Maybe Hermione traveled back in time and ended up in a situation where she and Severus had a relationship that led to her pregnancy. Another possibility is that a magical artifact forced them into a situation where they had to be together closely, and feelings developed over time, resulting in a pregnancy. Fanfiction writers love to take unexpected turns with characters' relationships.