One possible plot could be that Carlisle bites Harry as a last - resort to save his life. Harry then finds himself caught between the wizarding world and the vampire world. He has to deal with the prejudice from both sides. His friends at Hogwarts are scared of his new vampiric nature, and the vampires in Carlisle's coven are not sure if they can trust a wizard - turned - vampire. Harry then embarks on a journey to prove that he can be a part of both worlds and use his combined powers for good.
Maybe Carlisle bites Harry in an accidental encounter, and then Harry starts to develop some Twilight - like abilities while still having his wizarding powers. He has to figure out how to control these new powers and keep it a secret from his friends at Hogwarts.
Well, perhaps the fanfiction starts with Carlisle sensing Harry's loneliness and pain after all he's been through in the wizarding world. Carlisle offers Harry a home, and at first, Harry is hesitant but eventually accepts. In this new family, he could form a special bond with Edward. They might exchange knowledge, Harry about magic and Edward about the vampire existence. And the Cullens would have to deal with the possible danger that Voldemort could pose if he ever found out about Harry's new family.
One possible plot could be that Harry discovers his long - lost brother Carlisle. This could lead to a journey where Harry has to adapt to the vampire world that Carlisle is part of, while also bringing his own magic into it. Maybe they team up to fight against a common enemy.
One possible plot could be that a dark magic experiment gone wrong causes Carlisle to become pregnant. Harry, with his knowledge of various magics from the wizarding world, tries to find a way to reverse it or at least ensure a safe pregnancy. Along the way, they face opposition from both the vampire coven and some in the wizarding world who see this as an abomination.
Maybe Carlisle punishes Edward for endangering their family's secrecy in the vampire world. For example, if Edward did something reckless that could expose their existence to humans.
The bite might also change her appearance. She could develop paler skin, more prominent fangs, and a more alluring yet slightly menacing look. Her magic could be affected too. It might become intertwined with her new vampire nature, resulting in some unique and unpredictable magical effects that she would have to learn to control.
In this fanfiction, after Stiles gets bitten by a vampire, he might find himself in the middle of a vampire war. The vampire who bit him could belong to one faction, and now the other faction sees Stiles as a threat or a tool. He has to learn about vampire politics and hierarchies quickly. His friends, especially those who know about the supernatural, would try to protect him. Stiles would also have to deal with the physical and emotional changes that come with being a vampire, like the isolation that can come from living a nocturnal life and the fear of hurting those he loves.
In a Carlisle and Esme having a baby fanfiction, the plot could revolve around Esme's pregnancy. She might experience some difficulties due to her vampire nature. Carlisle, being a doctor, tries his best to ensure her and the baby's well - being. The family comes together to support them. The baby could have special powers, and they have to protect it from those who might want to harm it because of its uniqueness. The story could also show how the baby grows up in a family of vampires and how it adapts to its strange existence.
The plot could involve Carlisle and Esme using the chess game as a way to communicate their deeper emotions. Maybe each move represents a thought or feeling they have but are too reserved to say out loud. For example, a bold move on the chessboard could signify Carlisle's growing courage to be more open with Esme about his love for her.
In a 'Max Ride meets Carlisle' fanfiction, it could start with Max being curious about the rumors she hears of a 'gentle vampire' which is Carlisle. She tracks him down. Carlisle is initially wary but then realizes Max is not a threat. They start to share their stories. Max tells Carlisle about her time in the School and how she escaped, and Carlisle shares his long life journey and how he came to form his coven. As they talk, they discover they have more in common than they thought, like their sense of morality and the need to protect the innocent.
One possible plot could be that their baby has unique powers. Since Carlisle is a vampire and Bella has her own special traits, their child might inherit a combination. For example, it could have the ability to heal others like Carlisle, but also have some form of mental shielding like Bella. The story could focus on how they protect the baby from the vampire and werewolf worlds that might see it as a threat.