One common theme could be love and loyalty. Since they are mates, the story might revolve around their deep love for each other and their loyalty in the face of difficulties.
The theme of sacrifice could also be present. In some fanfictions, either Bella or the major might have to sacrifice something for the sake of their relationship or for the greater good. It could be sacrificing a personal goal, a friendship, or even their own safety. And of course, the theme of power dynamics within their relationship might be explored, especially if one of them has a certain power or status in the fictional universe.
Another theme might be adventure. They could be on some sort of adventure together, perhaps in a fantastical or dangerous world, and their relationship as mates helps them through it. For example, they might be fighting against some dark forces and their bond gives them strength. Also, self - discovery could be a theme. Bella might discover new aspects of herself through her relationship with the major.
Often, these fanfics explore the idea of redemption. Jasper may see Bella as a chance for redemption from his past. And for Bella, being with Jasper could be a way to find a different kind of life in the vampire world. Also, the theme of family is present. How their relationship affects the Cullen family and how the family reacts to it are often explored.
In 'bella is emmett's mate fanfiction', a frequent theme is the transformation of relationships. The friendship between Bella and the other Cullens would shift. For instance, her relationship with Rosalie would be very different as Emmett is Rosalie's mate in the original. There could also be a theme of new beginnings. It's like starting a whole new 'Twilight' - like story but with a different romantic core, which gives the writer a lot of room to explore different plot directions.
One common theme could be friendship. Since Bella is Kate's mate, their relationship might be explored in terms of how they become friends and support each other. Another theme could be adventure. They might go on some sort of journey together in the story.
Love against all odds is a big theme. Their bond as mates in the fanfiction usually has to overcome various obstacles. It could be differences in their personalities, or external forces like rivalries or family expectations. Also, the theme of transformation is common. As they get closer, they might change each other in positive ways, like becoming more confident or more understanding.
One common theme is the discovery of love. Bella and Godric often have to figure out their feelings for each other. Another theme is the struggle against society's expectations. Their relationship might not be accepted by all in their world. And power is also a theme, as Godric usually has a certain amount of power, and Bella's role as his mate might change her relationship with power as well.
One common theme is the exploration of a new relationship. Since Bella and Eric are not mates in the original, it's all about how they come to be mates in the fanfiction.
One common theme is the struggle against their different natures. Jasper has his violent past as a vampire, while Bella is a human. Fanfictions often explore how they deal with this difference.
Power is a common theme. Since Voldemort is a very powerful dark wizard and Bella is his devoted follower, their relationship in fanfiction often revolves around power sharing or Bella gaining power through her connection to Voldemort.
In 'bella and paul mate fanfiction', the theme of transformation is often present. Not just Bella's potential transformation into a werewolf's mate, but also the transformation of their relationship from hostility or indifference to love. There is also the theme of protection. Paul is a werewolf and has a natural instinct to protect, and this plays a big role in how he relates to Bella. And of course, the theme of love against all odds, as their relationship is not an easy one considering the complex world of Twilight that they are a part of.
The theme of self - discovery is also prevalent. As Bella gets involved with her mate, she often discovers new things about herself, her desires, and her place in the world.