Another theme is the growth of the relationship. The pregnancy can either strengthen or test the bond between Sirius and the OC. Sometimes it shows how they come closer together, learning about each other on a deeper level.
One great fanfic could be 'The Unforeseen Bond'. In it, the story weaves a complex plot around the OC's pregnancy. It delves into how Sirius Black reacts to the news and how their relationship evolves. The author does a wonderful job of capturing the essence of the characters within the framework of this unexpected situation.
Themes of secrecy and discovery are also common. In the wizarding world, there could be reasons to keep the pregnancy a secret, and then the story might revolve around how that secret is either kept or eventually discovered. Additionally, themes of love and sacrifice might play a big part, as Sirius might have to make sacrifices for the well - being of the pregnant situation and the future of the child.
One great Sirius Black and OC fanfiction is 'A Sirius Love'. It beautifully portrays the relationship between Sirius and the original character. The OC in this story has a unique backstory that draws Sirius in, and their interactions are full of emotion and depth.
Love and friendship are also big themes. The OC and Sirius usually start as friends or strangers and then develop a deep romantic relationship. Their love story might be set against the backdrop of the wizarding world's turmoil, like the fight against Voldemort. It adds an element of danger and excitement to their relationship.
One common theme is forbidden love. Since Sirius has his own complex situation within the wizarding world, often the relationship with the OC is something that is not easily accepted. For example, in many stories, his family might oppose it.
One of the main things that make it appealing is the chance to see Sirius Black in new situations. With an OC, the story can go in directions not possible in the original canon. The lemon elements, when done well, can enhance the emotional connection between the characters. For example, it can show a deeper level of intimacy and vulnerability. It also gives writers a chance to explore different aspects of the wizarding world that might not be covered in the main series, all while centering around the character of Sirius Black.
I'm not sure about specific 'sirius black pregnant fanfiction' works. But you can try searching on popular fanfiction websites like Archive of Our Own. There are likely many creative and interesting stories there that might match what you're looking for.
To start writing a Sirius Black OC fanfiction, begin with your OC's concept. Consider their magical abilities. Are they a powerful animagus like Sirius? Or do they have some other unique gift? Once you have that sorted, plan out the setting. Will it be mainly in Grimmauld Place or outside in the wizarding world? As for the relationship with Sirius, you can start from an initial encounter. Say, your OC bumps into Sirius in Diagon Alley. From there, build up the story, adding in elements of the wizarding world's lore and some drama to keep the readers interested.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3). Just type in 'Sirius Black OC' in the search bar, and then you can sort the results by popularity or kudos. This way, you'll likely find some of the well - liked fanfictions.