One common theme is family loyalty and betrayal. Since they come from the Black family, their actions towards each other and the family are often explored. For example, Sirius leaving the family while Regulus had a different path within it.
Another theme is redemption. Regulus, in some fanfictions, is on a journey to redeem himself after his actions related to Voldemort. And Sirius may play a part in that or be affected by it. It's an interesting dynamic to read about.
The theme of brotherly love also runs through a lot of Sirius x Regulus fanfiction. Despite their differences and the events that pull them apart, there is always an underlying love and connection that is often the focus of the story. It can be shown through memories, letters, or their interactions when they do meet.
The themes often revolve around the idea of secrets. Regulus may be hiding secrets from Sirius, which ultimately lead to his departure. This can create a sense of mystery and suspense in the fanfiction. Another theme is the power of choice. Regulus makes a choice to leave, and this choice has far - reaching consequences for both him and Sirius. It can also explore the theme of redemption. If Regulus has made some wrong choices, his leaving could be a step towards redeeming himself, either in his own eyes or in Sirius's eyes. Additionally, the theme of the impact of the wizarding war on personal relationships is quite common, as their situation may be a microcosm of the larger conflicts and divisions in the wizarding world.
One common theme is family loyalty. Sirius is driven by his love for his brother and his sense of family duty to save Regulus. It shows that no matter how estranged they may seem, family bonds are strong.
Another theme is the power of love and brotherhood. The fanfictions often show how Sirius' love and care for Regulus can overcome the barriers of the Black family's dark heritage and the dangerous magical world they live in. It's about how that connection between the two brothers can be a source of strength in difficult times.
One common theme is family loyalty. Sirius and Regulus come from the Black family, and fanfictions often explore how their loyalty to family, or lack thereof in Sirius' case, affects their actions and relationships. Another theme is redemption. Regulus, in particular, is often given a chance at redemption in these stories as he had a more complex and morally ambiguous role in the original series.
One common theme is their relationship as brothers. Many fics explore the complex dynamic between them, from their early days in the Black family to their diverging paths. For example, some stories focus on how Sirius's rebellious nature clashed with Regulus's initial loyalty to the family.
Another theme is secrecy. Given Regulus' secretive nature in the Harry Potter universe, many fanfictions play on the idea of him having to keep his relationship with the character a secret from his family or other dark wizards. This adds an element of mystery and danger to the story.
A theme that often shows up is mystery. Given Regulus' secretive actions in the original story, fanfictions often build on this. The reader may be drawn into his world of secrets, trying to uncover what he's really up to. For instance, the reader could be involved in his search for the Horcruxes. Also, the theme of loyalty can be explored. Is the reader loyal to Regulus despite his ties to the Death Eaters? And how does Regulus' loyalty shift as he gets closer to the reader?
Friendship is a very common theme. Their bond as Marauders is often explored, like how they always had each other's backs. For example, in many fanfictions, they stand up for each other against the pure - blood supremacists at Hogwarts.
One common theme is the 'what if' factor. Writers often explore what would have happened if Sirius and Lily had a different relationship. Another theme is the idea of forbidden love, considering Lily was with James and Sirius was his friend. Also, themes of loyalty and friendship are often intertwined as they navigate their complex feelings.
One common theme is redemption. Regulus was once a Death Eater, and through his relationship with Harry, he often seeks redemption. For example, in many fanfictions, he tries to make up for his past mistakes by helping Harry in his fight against Voldemort.