One common theme is family building. It shows how Lena and Kara come together to create a family unit with the baby. Another theme is the exploration of their relationship. Having a baby often tests and deepens their bond.
One possible plot could be that Lena and Kara are in a dangerous situation together. As they face a powerful enemy, they realize their deep feelings for each other. In a moment of intense emotion, perhaps after one saves the other's life, they share a kiss.
One possible fanfiction could be about Lena Luthor becoming a mentor to young Kara Danvers. Lena, with her intelligence and resources, could help Kara understand the complex world around her while also learning to control her powers better. Maybe Lena discovers Kara's identity early on and decides to guide her in secret, away from the prying eyes of Lex Luthor and other potential threats.
One idea could be that they overcome some external threat together which makes them realize their love is unbreakable and they decide to get married. Maybe they fight against an anti - alien group that targets Kara, and Lena uses her intelligence and resources to protect her. This shared experience brings them closer than ever.
Another great one is 'Baby Steps'. This fanfiction delves deep into the emotions of Lena and Kara as they navigate the world of parenting. It has some really cute scenes where they learn to take care of the baby, like the first time they change a diaper or put the baby to sleep, all while dealing with their own insecurities and the reactions of their friends and family.
During the pregnancy, their relationship could transform in many ways. They would become more empathetic towards each other. Kara, with her super - strength, might be more cautious around Lena, not wanting to accidentally harm her. Lena, on the other hand, would use her intelligence to research the best ways to have a healthy pregnancy for both of them. They would also have a new shared purpose in life, which is to raise their children well, and this would create a deeper and more complex relationship dynamic than before.
They would support each other's careers more than ever. Kara would be there for Lena's business meetings, using her super - speed to help Lena get things done quickly. And Lena would be helping Kara with her journalism work, using her tech - savvy skills. Their relationship would also deepen on an emotional level, sharing their fears and dreams every night.
There might be a fanfiction where Kara's identity as Supergirl is revealed in a way that hurts her deeply, and Lena, despite their past differences, stands by her side. It could explore their complex relationship and how they deal with the fallout together.