One idea could be that Rebekah's son discovers a hidden power within him that links to the family's dark past. He might struggle to control it while also trying to fit into the human world. For example, he could accidentally use this power during a school event, causing chaos.
Another plot could revolve around Rebekah's son being hunted by an ancient enemy of the Mikaelsons. He has to rely on his wits and the few friends he has made in the supernatural community. This would involve a lot of running, hiding, and trying to figure out the motives of the enemy. Maybe he discovers a long - forgotten prophecy about himself along the way.
One idea could be the baby having unique powers that attract both danger and allies. Maybe the baby's powers are a mystery even to Rebekah at first, and she has to protect it from those who would use it for their own gain. Another plot could be about the baby growing up in a world full of supernatural politics, with Rebekah trying to shield it from the darker aspects of that world. Also, a story where the baby forms an unexpected bond with a character who was initially an enemy could be really interesting.
A more complex plot could be that the OC is a time - traveler. They accidentally land in Rebekah's time period. At first, Rebekah is suspicious of the OC, but as the OC reveals knowledge of future events that could help Rebekah and her family, they form an alliance. However, changing the past has unforeseen consequences that they must deal with.
One plot idea could be an OC who is a long - lost relative of the Mikaelsons. They show up in Mystic Falls and at first, the Mikaelsons are suspicious. But as time goes on, they start to form a bond, especially Rebekah. Another could be an OC who is a powerful witch and is brought in to help the Mikaelsons with a new threat. Rebekah might initially be jealous of the OC's power but then realizes they can work together. A third idea is an OC who is a human with a special ability to see the future. Rebekah tries to use this to her advantage in the vampire - filled world she lives in.
The plot might involve Harry trying to hide his true identity as a Mikaelson. He could struggle with the fact that he's different from other wizards. His relationship with his friends, like Hermione and Ron, could be strained as he tries to keep this secret. Also, the Mikaelson family might try to get him involved in their vampire world affairs, which would create a whole new set of challenges for Harry.
Maybe Harry discovers his Mikaelson heritage when strange things start to happen to him during his time at Hogwarts. His newfound powers could attract the attention of both the wizarding world and the supernatural world from Klaus' side, leading to a complex web of alliances and rivalries. He might have to learn how to balance his wizarding skills with his vampire - like abilities.
Perhaps in the fanfiction, Rebekah is a transfer student from a different magical school. She forms an unlikely friendship with Hermione. Together, they work on a project that combines the magic of the Vampire Diaries' world (where Rebekah is from) and the wizarding world of Harry Potter. This could lead to new spells being discovered. And Rebekah might also have some romantic tension with one of the male characters, like Ron or Draco.
One idea could be a story where the baby Mikaelson has unique powers that start to manifest at a very young age. Maybe they can communicate with spirits, and this leads to all sorts of adventures as the family tries to protect the baby from those who might want to use their powers.
Caroline Forbes would be an excellent ally. She's strong - willed and has a good heart. She could help Rebekah's son navigate the social aspects of the vampire world, like how to handle vampire politics. Also, her friendship with the Mikaelsons could make her a natural protector for Rebekah's son.
Well, the baby could be born with a condition that requires it to be in a certain magical environment to survive. This would lead the Mikaelsons on a quest to find and create such an environment. And what if the baby's presence starts to change the power dynamics in the supernatural community? Some might see it as a threat while others as a new hope for a different kind of future.
One idea could be that Elijah discovers he is going to be a father during a time of great turmoil in the supernatural world. His family's enemies might see this as a weakness and target him and his unborn child. Another plot could involve Elijah trying to protect the mother of his child from the dangerous vampire politics and ancient curses that could harm her or the baby. Maybe he has to make a deal with a powerful witch to ensure a safe pregnancy for the mother.