Well, one possibility could be that it focuses on how they prepare for the baby. Maybe they start looking for a safe place to raise the child, like a secluded cottage away from all the chaos. And they might also start gathering supplies for the baby.
The plot could involve the reactions of their friends and allies. Some might be overjoyed and offer support, while others could be worried about the implications of a half - Emilia, half - Maou baby. It could also show how Emilia and Maou's relationship evolves during this time, becoming stronger as they face this new chapter together.
Another aspect could be the challenges they face due to their different natures. Emilia is an elf - like being and Maou has his own demonic nature. There could be concerns about the baby inheriting certain powers or facing discrimination from different factions. They would then have to find ways to protect their unborn child and ensure its future in a world that may not be fully accepting.