There are some. However, the quality can vary greatly. Some fanfictions might focus on the emotional aspects of this new family connection, while others could be more action - packed, perhaps involving Bella's new role in the Volturi family if Caius is her father. It really depends on what you're looking for in a fanfiction.
One common theme is identity. Bella has to grapple with who she is now that she has a different family origin. Another theme is power dynamics, as being Caius' daughter would likely place her in a different position of power within the Twilight universe. Also, family relationships are explored, like how her new connection to Caius and the Volturi would affect her relationships with the Cullens.
One idea could be that this relationship creates a huge power dynamic shift in the Volturi world. Since Bella is Aro's daughter, she might have unique powers or a special status that Caius is attracted to. It could also lead to a lot of internal conflict within the Volturi, as some may see her as an outsider despite her relation to Aro. And her relationship with Caius might be a way for her to gain more influence and change the Volturi's ways from within.
At first, it might be a bit rocky. Bella, being human and now blind, is in a very vulnerable state. Caius, as a powerful vampire, may come off as intimidating. But as time goes on, they start to develop a deep bond. Caius learns to be more gentle and caring, and Bella starts to trust him more and more.
Well, Caius could be very possessive and see Bella's blindness as something that makes her even more his. He would be by her side all the time, guiding her physically when needed. He might also share his vampire senses with her in some way, like describing the world around them in vivid detail so that she can 'see' through his words. And he would definitely be very angry if anyone made fun of or took advantage of her blindness.
In this scenario, Bella's life would be full of political intrigue. She'd be caught between her father Aro's expectations and her relationship with Caius. Her relationship with Caius might not be a smooth one at first. They might have to overcome their differences, like Caius' traditional views on vampires and Bella's more modern or human - influenced ideas. But as they grow closer, they could start to change each other's perspectives.
One common theme is the struggle between different vampire clans. Since Caius is part of the Volturi and Bella has her own connections, this often creates a backdrop of power struggles and politics in the fanfiction.
Bella, a character known from the Twilight series, is one of the main characters. She is usually the focus of the story's emotional arc. Caius, from the Volturi, is the other main character. His actions and decisions, especially in relation to Bella, form the core of the conflict and development in the fanfiction. Their personalities, which are often a blend of what we know from the original source and new interpretations, are what make these stories interesting.
Often, bella x caius fanfiction features a relationship that is somewhat dark and intense. Caius being part of the Volturi has his own set of power and authority, which adds an element of danger to the relationship with Bella.
One great Caius Volturi and Bella fanfiction is 'The Volturi's Obsession'. It explores an alternate universe where Caius has a more complex relationship with Bella. Another is 'Caius and Bella: A Forbidden Bond' which delves into the challenges they face due to their different natures.