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.
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.
One common theme is the struggle against the odds. Since Bella and Caius are from different 'worlds' in a sense, they often have to face opposition from other vampires or even Bella's human friends. Another theme is the discovery of a deep, new connection. It's about how they come to realize their bond as mates.
Love triangles are a big part of these fanfictions. Bella is in a unique position with Carlisle and Caius. There's also the theme of self - discovery. As Bella navigates this new relationship, she discovers new sides of herself. And the theme of family is there too, as Carlisle has his own family and Caius has his own group, and Bella has to find her place within these complex family structures.
One popular 'bella is carlisle and caius mate fanfiction' is 'Twilight Reimagined'. It offers a unique take on the relationships, with interesting character developments.
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.
I know of a 'bella is caius mate fanfiction' titled 'The Caius - Bella Bond'. This story begins with Bella being drawn to Caius in an unexpected way. As the story progresses, it shows their growing bond and how they deal with the enmity from other vampires. It's a great read for those interested in this pairing. There are also many other fanfictions out there that you can explore on various fanfiction platforms.
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.