One idea could be that they struggle to balance their work with the upcoming baby. For example, Lucifer's devil - related duties and Chloe's police work. Another could be that they have different ideas about how to raise the child, given their very different backgrounds. Maybe Lucifer wants to raise the child with a more 'devil - may - care' attitude while Chloe is all about discipline and rules.
One idea could be that they face challenges in their relationship due to the pregnancy. Maybe Lucifer is worried about his devilish nature affecting the baby, while Chloe is trying to balance her detective work with the new situation. Another plot could involve them having to protect the unborn child from supernatural threats, as Lucifer's world is full of such things.
Maybe the pregnancy is unexpected, and they initially panic. But then they start to get excited about building a family together. Chloe could start to train Lucifer on how to be a good father, like teaching him about baby care and normal family values, which would be a big change for him since he's from Hell.
One idea could be that the baby has some sort of special power. Maybe it can see things that others can't, like angels or demons in their true forms. This would add an interesting dynamic as Lucifer and Chloe try to understand and protect their child from the otherworldly forces that might be interested in the baby's power.
One common plot idea is how they deal with the challenges of having a baby while Lucifer is still adjusting to his life on Earth. For example, he might be worried about his devilish nature affecting the baby in some way.
One idea could be that they face challenges in their relationship due to the unexpected pregnancy. For example, Oliver might worry about how his vigilante life could affect the baby and Chloe. Another could be that they go on a journey to find a safe place for their family, away from the threats in Smallville. They could also have to deal with the reactions of their friends and family, some of whom might not be as supportive as they hoped.
One common theme is the exploration of their relationship dynamics when they are about to become parents. It often shows how they support each other during the pregnancy.
One possible plotline could be Chloe's struggle to balance her pregnancy with her journalistic work in Smallville. She might face challenges like keeping her pregnancy a secret from certain people who could use it against her. Another could be the reaction of her friends, especially Clark. Clark might feel a new sense of protectiveness towards her and help her deal with any strange happenings in town that could endanger her or the baby.
The fanfiction could also be about the challenges Chloe faces during her pregnancy. For example, she might have health problems during the pregnancy. She could also face social issues, like dealing with people who judge her for being pregnant at a certain age or in a certain situation. The story could show how she overcomes these difficulties and grows as a person.
One idea could be exploring how Yennefer deals with the physical and emotional changes during pregnancy while still being a powerful sorceress. Maybe she has to find a way to protect her unborn child from the many enemies she has made.
One idea could be exploring how she and her partner (like Percy) adjust to the news. They might have to deal with the reactions of their friends and family. Another could be the challenges she faces during the pregnancy, like her still wanting to be involved in heroic adventures but having to be more cautious.