You can start by giving the OC a distinct backstory. For example, if they're a vampire, explain how they were turned and what their human life was like. This will shape their personality and values.
One idea could be that the OC is a powerful witch who gets caught in the middle of the Salvatore - Rebekah drama. She might initially befriend Rebekah, not knowing her full vampire nature, and then fall for one of the Salvatores. This creates a love triangle full of supernatural twists.
One great fanfiction in this category is 'Rebekah's New Love' where the OC is a half - vampire, half - witch. It has a really engaging plot that weaves in the relationship between Rebekah and the OC while also involving the Salvatores in a very interesting way. Another one is 'Salvatore's Secret Heir' which focuses more on the mystery aspect of the OC's identity and how it affects their relationship with Rebekah.
In a Rebekah Mikaelson x OC Salvatore fanfiction, one common theme could be redemption. Maybe the OC has a dark past and Rebekah sees something in them that she wants to save. Or it could be about power struggles. The OC, being related to the Salvatores, might have access to certain resources or knowledge that Rebekah wants. Another aspect could be the exploration of forbidden love. Since the Vampire Diaries is full of complex relationships, this pairing can add another layer of complexity. Writers often use this to create a unique and engaging story that stands out from the original plot of the show.
One popular trope is the 'forbidden love' aspect. Since Damon has his own complex history and relationships within the show's canon, his relationship with an OC is often seen as something that goes against the norm or is frowned upon by other characters. Another common trope is the 'OC as the savior'. The OC might be the one to rescue Damon from some sort of emotional or physical danger, which then starts their relationship on a path of mutual dependence.
To develop Rebekah, explore her past more. How has her time as a vampire affected her relationships? What are her hopes and dreams? For the OC, build their backstory gradually. For example, if they're a werewolf, how did they become one? How has it shaped their view of the world? Let their relationship develop organically. As they interact, they learn more about each other and change in response to each other.
One idea could be that the OC is a new vampire in town. Rebekah takes an interest in them because they seem different from the other vampires she's known. They could go on adventures together, facing other supernatural threats while also exploring their growing relationship.
Stefan Salvatore x OC fanfiction often explores unique relationships. In such stories, the OC (Original Character) can bring new dynamics to the 'The Vampire Diaries' universe. It allows fans to create their own storylines that might not be possible with just the canon characters. For example, the OC could be a witch who has a special connection with Stefan, leading to all kinds of adventures and romances.
One common theme is friendship. Many fanfics explore how an original character can form a deep and meaningful friendship with Rebekah. Another theme is adventure. Since the Mikaelson world is full of danger and mystery, the oc often gets involved in adventures with Rebekah. For example, they might go on a quest to find a lost artifact or face a new supernatural threat.