Fanfiction.net is a really popular platform for 'bella swan and carlisle cullen fanfic'. It has a large collection of stories, ranging from different genres and writing styles. You can easily search for specific tags related to bella and carlisle to find the fanfics you're interested in.
Another fanfic could be 'The Unforeseen Alliance'. In this, bella and carlisle find themselves in a situation where they have to team up against a common enemy. It's full of action and also shows the growth of their relationship as they learn to trust each other more.
One common theme is the exploration of a forbidden relationship. Since Carlisle is much older and in a different position in the vampire hierarchy compared to Bella, it creates an interesting dynamic. Another theme is the idea of mentorship. Carlisle often acts as a mentor figure to Bella, guiding her through the vampire world.
You can start by looking on Fanfiction.net. It has a large collection of Twilight - related fanfictions, including many that focus on Bella and Carlisle. Archive of Our Own (AO3) is also a great place. It has a wide variety of fan - created works, and you can easily search for specific pairings like Bella Swan and Carlisle Cullen.
One great fanfiction could be 'The Unforeseen Bond'. It delves into a different kind of relationship between Bella and Carlisle, where they form an unexpected friendship that has a profound impact on the Cullen family dynamics. Another one might be 'A New Perspective' which shows Bella's view of Carlisle as a mentor figure rather than just Edward's father. And then there's 'Carlisle's Concerns', which focuses on Carlisle's internal thoughts regarding Bella's presence in their vampire world.
One interesting fanfiction could be about Bella having special powers that Carlisle discovers and they go on a journey to understand them. It might involve them traveling to different vampire covens to seek knowledge.
There's 'A Different Path'. This fanfic takes a unique turn where Bella discovers she has some special abilities that Carlisle is intrigued by. It's filled with mystery and some really cool plot twists that keep you hooked from start to finish.
Well, Carlisle is a very different kind of vampire. He has a sense of honor and ethics. In relation to Bella, his connection was mainly through Edward. But Carlisle was always there to support Bella, to make sure she was okay in their dangerous vampire world. He was like a guiding light for her, not a romantic partner. Their relationship was built on his respect for her humanity and her place in Edward's life.
Their relationship can be developed through shared experiences. For example, they could face a common enemy together. This would force them to rely on each other and understand each other's strengths and weaknesses.
A plot could revolve around Carlisle and Bella going on a secret mission together. Maybe they have to find a lost ancient vampire artifact that could change the future of the vampire world. Along the way, they develop a deep bond and respect for each other.