One common theme could be the challenges and joys of impending motherhood. The character Lily might be depicted as dealing with the physical and emotional changes. Another theme could be the reaction of those around her, like her partner, family or friends.
One idea could be that Ginny discovers she's pregnant during a time of relative peace in the wizarding world. She might initially be worried about how Harry will react, but he is overjoyed. As the pregnancy progresses, Ginny could start to train her unborn child in magic in a very gentle way, like whispering spells near her belly. Lily could grow up to be a powerful witch with unique abilities, perhaps having a special connection to the magical creatures in the Forbidden Forest due to Ginny's own experiences there.
A common theme is the struggle between their personal dreams and the new reality of having a baby. For example, if they had dreams of traveling the world or pursuing certain careers, those might have to be put on hold. Family support or lack thereof is also a theme. Whether their families are there for them or not can greatly affect their pregnancy journey. Additionally, the theme of fear is often present. They are likely to be afraid of the unknowns of pregnancy, childbirth, and raising a child.
One common theme could be the conflicted emotions of Snape. Given his complex relationship with Lily, his reaction to her pregnancy might be a central aspect, like dealing with his unrequited love in a new context.
The main characters are clearly Lily and Severus. Lily is often portrayed as a kind - hearted and strong - willed character. Severus, on the other hand, is usually depicted as complex, with his own insecurities and hidden depths.
One popular Oliver Queen pregnant fanfiction might involve a storyline where his relationship with a female character deepens in an unexpected way. For example, in some stories, it could be a result of a magical or scientific accident that leads to the pregnancy. This adds an interesting twist to his character's journey.
One common theme is the anticipation and excitement of becoming parents. The characters, Lilly and Oliver, might be shown daydreaming about their future with the baby. Another theme could be the changes in their relationship. For instance, they might become closer as they share this new experience.
Well, usually in fanfiction communities, if you're looking for 'lily pregnant fanfiction', you might want to start by looking at the relevant fandom forums. Some fans might share their favorite stories or even write their own. However, it really depends on which 'lily' the fanfiction is based on. Is it from a particular book, movie or TV show? Knowing that would narrow down your search a great deal.
One possible plot could be the challenges they face in their relationship due to the unexpected pregnancy. Maybe they have to deal with the reactions of their friends and family. Another plot could involve how they prepare for the arrival of the baby, like Severus trying to be more responsible and Lily dealing with her own fears and hopes.
Fanfiction.net is also a great place to search. Many fans post their Oliver Queen - related fanfictions there. However, the search might not be as refined as on AO3. You may need to spend some time browsing through different categories related to Arrow or Oliver Queen to find the pregnant fanfiction you're interested in.