One common trope could be the 'overprotective partner' trope. Luther, being the strong one, might be overly protective of Allison during her pregnancy. Another could be the 'unexpected pregnancy' trope, which could lead to a lot of drama and character development.
Well, clearly Emily and Allison are the main characters. They are the ones who are pregnant, so the story likely focuses on their experiences, emotions, and the changes in their lives.
One common theme could be the reactions of the other characters. For example, her family members in the story might have different responses to her pregnancy, ranging from joy to concern. Another theme could be how Allison herself deals with the pregnancy, whether it was planned or unplanned and how it affects her goals and relationships.
One possible storyline could be about how they navigate the challenges of impending parenthood while also dealing with their unique family situation. For example, they might worry about how their child will be received by the rest of their rather unconventional family.
One possible storyline could be about how Emily and Allison support each other through their pregnancies. They might share their experiences, fears, and joys. For example, they could go shopping for baby clothes together and discuss nursery ideas.
Love and family are big themes too. The stories often show how the love between Steve and the OC grows deeper during the pregnancy. And they start to build a family unit, which might be different from a normal family because of Steve's status. It shows how they create their own version of a loving family in the face of all the challenges that come with the situation.
Another option could be FanFiction.net. However, the quality and quantity of stories might vary. It's also important to note that when you search, make sure to check the tags and summaries carefully to ensure it's exactly what you're looking for. Sometimes, the stories might not be exactly about Allison being pregnant but could be related in some other way.
One great fanfiction in this category is 'A New Beginning'. It beautifully explores the relationship between Steve Rogers and the original character as she discovers she's pregnant. It delves into their emotions, from Steve's initial shock to his growing excitement and protectiveness. The story also shows how the OC copes with the changes in her life, both physically and emotionally, while being in a relationship with a superhero like Steve.
One interesting plot could be the challenges they face in a world that is not used to male pregnancy. They might have to deal with public reactions, both positive and negative. Another plot could be how they support each other through the physical and emotional changes that come with pregnancy.