A theme of sacrifice could also be present. Maybe there are situations where either Bella or Amun has to sacrifice something for the sake of their relationship or for the greater good of the world they exist in. This could add depth and drama to the fanfiction story.
In a 'bella and amun mates fanfiction', it could be really interesting. Maybe it starts with an unexpected encounter between Bella and Amun. Then, as they get to know each other more, their relationship deepens. There could be all sorts of plot twists, like conflicts with other characters who oppose their union, or challenges they face together. It could also delve into the unique aspects of their personalities and how they complement each other as mates.
One common theme is the exploration of forbidden love. Since Amun is an ancient vampire and Bella is a human - turned - vampire, their relationship often goes against the norms of their respective vampire clans.
One possible theme could be friendship. Even though they are mates, a strong foundation of friendship is often important. They might rely on their friendship to get through difficult times. Another theme could be loyalty. They would be loyal to each other no matter what challenges come their way. It could also have a theme of discovery, as they discover new things about themselves and each other as their relationship progresses.
Another theme might be self - discovery. Bella might learn more about herself through her relationships with the three mates. She could discover what she truly wants in a partner and in life in general. The story could show her growth as a character as she deals with these complex relationships.
Another plot could be that they are on opposite sides of a conflict initially. But as they realize they are mates, they have to find a way to reconcile their differences and work together. This could involve a lot of internal struggle for both of them as they deal with loyalty to their respective sides and their new - found bond.
One possible plot twist could be that Bella discovers Caius has a hidden agenda all along, and it's not just about their relationship. Maybe he's using their bond to gain power within the vampire world. Another twist might be that Bella has a secret power that is awakened by her connection with Caius, and this power changes the dynamics of their relationship and the entire vampire community.
Perhaps there is an external threat to their mateship. A powerful villain could be trying to break them apart for some reason, like using magic or blackmail. So, they have to fight against this threat to stay together.
The theme of sacrifice is also quite prevalent. For example, they might sacrifice their own desires or opportunities for the sake of their relationship. Also, the theme of family acceptance. Sometimes their relationship is not initially accepted by their families, and they have to work through that.
One common theme is the struggle against the odds. Since their relationship might not be accepted easily in the vampire world, they often have to fight for their love.
Love and loyalty are very common themes. Their relationship as mates is centered around love. They are often shown to be loyal to each other, no matter what challenges come their way. In many fanfictions, this loyalty is tested, but they always come out stronger in the end. Also, discovery is a theme, as they discover new things about each other and themselves through their relationship.