Yes, there might be. Fanfiction platforms often have a wide variety of creative works. You can try searching on popular fanfic sites like Archive of Our Own or FanFiction.net.
It could be full of drama. Maybe there would be a lot of internal conflict within Lucifer about becoming a father, and Chloe might have to deal with the reactions of her friends and family.
In this fanfic, their relationship would be transformed. There would be a new level of intimacy as they are about to become parents. They would share more tender moments, like Lucifer feeling the baby kick for the first time. However, they would also face new challenges. The stress of the pregnancy and the unknown future could put a strain on their relationship at times. But overall, their love for each other and for their unborn child would keep them together, working through any difficulties that come their way.
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 possible plot twist could be that the pregnancy is not as straightforward as it seems. Maybe there are some supernatural elements involved, like the baby having special powers. For example, the baby could be a key to a different realm or have the ability to manipulate time. Another plot twist could be that there are enemies who want to harm Chloe because of the pregnancy, adding a lot of action and suspense to the fanfic.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfics, and you can search for 'Chloe and Lucifer pregnant' in the search bar. There are likely to be many different takes on this scenario written by various authors.
In the 3x11 fanfic of Chloe and Lucifer, their relationship might be explored in unique ways. Maybe it shows a deeper emotional connection that wasn't fully shown in the original series at that point. It could also introduce new plotlines centered around their characters, like how they deal with a particular crisis together.
One potential antagonist could be Lucifer's father. He might not approve of the union or the baby, seeing it as a disruption to his grand plans or as something that could change Lucifer in a way he doesn't want. Another could be some of the demons from Hell who see the baby as a potential threat to their power or existence if it has some sort of unique abilities.
The theme of good vs. evil is common too. Chloe, representing the good, and Lucifer, with his devilish past, come together. Fanfics often play with this dynamic, like how they influence each other's views on morality and how they navigate the world with their different natures.
Another theme is the battle between good and evil. Lucifer, being the devil, constantly struggles with his nature. In fanfic, this can be shown in different ways, like how Chloe influences him to lean more towards good. It also delves into the idea of redemption, which is related to the good - vs - evil theme.