Love is a very common theme. The love that develops between Sirius Black and the OC can range from a slow - burning romance to an instant attraction. Another common theme is redemption. Sirius may find redemption through his relationship with the OC.
Love and friendship are also common themes. The OC often forms a deep bond with Sirius, whether it's a romantic love or a strong friendship. This bond helps to develop both characters and drive the story forward. They might go through challenges together and their relationship grows stronger as a result.
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.
Love and friendship are very common themes. Since Sirius is such a complex and beloved character, many fanfics explore the deepening relationship between the reader and him, whether it's a slow - burn romance or a strong platonic bond.
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.
Love and Romance are very common. Since it's about Sirius Black and an OC, the development of their relationship, from the first meeting to falling in love, is often a central theme.
Love, both platonic and sometimes romantic, is also a major theme. Their relationship had a special connection, and fanfics might show how that connection could develop into something more. It's about the unspoken feelings they might have had for each other.
One common theme is redemption. Since Regulus was involved with the Death Eaters and then had a change of heart, many fanfics use his relationship with the OC to explore his journey towards redemption. For example, the OC might be the one who helps him see the error of his ways.
One common theme is friendship. Since Sirius has strong friendships in the original story, in these fanfics, his friends often play important roles in his life and character development. For example, how they support him during tough times.
A frequently seen theme is the struggle against the dark side. In the context of the Harry Potter universe, Sirius has his own battles with the dark forces. Fanfics with female characters often involve them joining Sirius in his fight, either directly or by providing moral support. Also, self - discovery is a common theme. The female characters often grow and learn about themselves through their interactions with Sirius.
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.