Identity is a common theme in such fanfictions. Both Edward and Harry have their own identities within their respective worlds, and when they become mates, they have to re - evaluate and sometimes re - define who they are. There's also the theme of acceptance. Their relationship may not be accepted by everyone in their communities, so they have to fight for acceptance while also dealing with their new - found bond as mates. This creates a lot of drama and interesting plotlines in the fanfictions.
Love and devotion are very common themes. Since they are mates, their deep love for each other is often explored. Another theme is the struggle between their different natures, with Edward being a vampire and Bella being human. Protection also comes up a lot, as Edward is always eager to protect Bella.
One common theme is the idea of overcoming differences. Since Edward is a vampire and Jacob is a werewolf, their different natures create a lot of tension which they have to overcome in most fanfictions. Another theme is the power of love and how it can bridge the gap between two very different beings. Also, the concept of loyalty often comes up as they have to be loyal to each other and their new relationship in the face of opposition from their respective groups.
One common theme is the exploration of their eternal bond. Since they are vampire mates, their connection is supposed to last forever, and many fanfictions focus on how they maintain and strengthen this bond. Another theme is the challenges they face due to their different natures. Bella was once human, and becoming a vampire brings a whole new set of issues. Also, the theme of protecting each other and their family is quite common. They are mates, so they will do anything to keep each other safe.
One common theme is the exploration of a forbidden or unexpected love. Since they were previously seen as family within the Cullen coven, their new relationship as mates goes against the normal perception. Another theme is the discovery of self - identity. As they become mates, they might question who they are within the family and the vampire world anew. For example, Esme might wonder how her role as Carlisle's wife was different from her new role as Edward's mate.
One common theme is the exploration of their different personalities coming together. Harry is often seen as the brave hero, while Luna is the eccentric and dreamy character. Their relationship in these fanfictions usually shows how they balance each other out.
Friendship is a very common theme. Harry and his mates often rely on each other and form deep emotional bonds. Another theme is adventure, as they usually embark on various quests and challenges within the wizarding world.
Well, a major theme is the power of forgiveness. Harry has to forgive Snape for his past actions, and Snape has to forgive Harry for being James Potter's son. Understanding is also common. They come to understand each other's motives and personalities better. And growth. Both characters grow as individuals because of their new - found relationship as mates. They become more empathetic and less judgmental towards each other.
One of the main themes is the discovery of a shared destiny. In many 'Harry and Merlin Mates' fanfictions, they find out that they are meant to be together for a greater purpose, like saving the magical world. Also, the theme of mentorship exists. Merlin, being more experienced in magic, often mentors Harry, and this relationship dynamic is explored in different ways in these fanfictions.
One common theme is redemption. Draco often has a chance to redeem himself in the eyes of Harry and others. Another theme is friendship overcoming enmity. They start as enemies but through various events, they become friends or even more. And the theme of self - discovery is also present as they learn more about themselves through their relationship.
Forbidden love is also a big theme. Given their past enmity and the different paths they were on in the original story, their relationship as mates is often portrayed as something that is not easily accepted in the wizarding society. Writers like to play with this idea of two characters who were supposed to be enemies falling in love.