One common theme is the exploration of forbidden love. Since Carlisle is an older vampire and Bella is a human (initially), their relationship goes against the norms of both the vampire and human worlds.
He becomes more vulnerable. Usually, Carlisle is seen as this strong, composed leader. But when he falls in love with Bella, his emotions start to get the better of him at times. He might second - guess his decisions more often.
One interesting story could be where Carlisle's love for Bella is a slow - burning one. He tries to resist it at first because of the complications it might bring with Edward and the rest of the family. But as time goes on, he realizes he can't help his feelings.
One popular 'bella falls in love with carlisle fanfiction' is 'A Different Kind of Love'. It explores a unique take on their relationship, with Bella being drawn to Carlisle's wisdom and kindness in a more profound way than in the original story.
In the fanfiction, Carlisle's sense of duty to his family and the vampire code might be a hurdle. He has to balance his feelings for Bella with his responsibilities to the Cullen family. Also, Bella's own human life and her relationships with other humans, like her father, could be a complication. How can she maintain those relationships while being in love with Carlisle? There's also the issue of secrecy. Their relationship has to be kept hidden from the outside world to protect both of them.
In some fanfictions, their relationship might start with Carlisle being drawn to Bella's unique spirit. He, as an older and more experienced vampire, is intrigued by her resilience. Maybe he first notices her when she enters the Cullen family's orbit, and from there, a slow - burning attraction begins to form as they interact more and get to know each other on a deeper level.
No. In the original "Twilight" series, Bella is in a relationship with Edward, and Carlisle is more like a father figure. Writing such fanfiction goes against the original intention of the story and may also violate the ethical and moral boundaries of the fanfiction community.
The Cullen family members are important characters too. Edward, for example, might have an interesting dynamic with Bella in this fanfiction. He could be either protective or jealous of Carlisle's special relationship with her.
One common theme could be the exploration of a forbidden or unexpected relationship. Since Carlisle is an older, more reserved character and Bella has her own set of relationships in the original series, this pairing is quite different. Another theme might be the re - imagining of the Twilight world's power dynamics and how this relationship would affect the other characters around them.
There might be some out there, but Twilight fanfiction often varies greatly in quality. Some can be really well - written with good character development, while others might not be so great. It's a matter of searching through different fanfiction platforms to find ones that meet your expectations.