One common theme is loyalty. Since they are brothers, their loyalty to each other is often a central focus. They will go to great lengths to protect one another.
One common theme is friendship. Their relationship is often at the heart of the stories, showing how they support and grow with each other. Another is loyalty. Arthur and Merlin are extremely loyal to each other in the original series, and this is often emphasized in fanfiction.
One common theme is the exploration of gender roles. Since it's a male pregnancy, it challenges the traditional ideas of male and female roles. Another theme is the deepening of the relationship between Merlin and Arthur. The pregnancy often serves as a catalyst for them to become closer and more reliant on each other.
Love, in different forms, is a recurring theme. It could be platonic love that is so strong it's like a family bond. Or it could be a romantic love that the authors explore in a very subtle or sometimes more obvious way. This love is often what drives them to make sacrifices for each other in the fanfiction stories.
One common theme is the power dynamic. Since Merlin has magic and Arthur is the king, it's interesting to see how a female Merlin would handle that. Another theme is love and loyalty. Their relationship, whether it's platonic or romantic, is often at the center.
In Merlin and Arthur gay fanfiction, a prevalent theme is the exploration of identity. Arthur, as a prince, has certain expectations placed on him, and exploring his identity as a gay man is a significant aspect. Merlin, too, with his magical abilities and his role as a servant, has his own identity journey. Another common theme is the idea of sacrifice. They might be willing to sacrifice their own desires or positions for the sake of the other, which is a very romantic and noble concept often explored in these fanfictions.
Another theme is the test of their relationship. The hotel can be a place full of challenges and temptations. It could be other people trying to come between them or some difficult situations that make them question their loyalty to each other. Like in some fanfictions, a powerful sorceress at the hotel tries to charm Arthur away from Merlin, but they overcome it and their relationship becomes stronger.
One common theme is loyalty. In these fanfictions, Merlin's loyalty to Arthur takes on a new, more intense dimension when there are romantic feelings involved. Another theme is sacrifice. Often, either Merlin or Arthur is willing to sacrifice a great deal for the other, which is a big part of their relationship in these stories.
Love and protection are common themes. Arthur's possessiveness often comes from his love for Merlin and his desire to protect him from harm. For example, in many fanfics, Arthur will not allow others to harm or even insult Merlin.
One common theme is loyalty. Arthur's loyalty to Merlin drives his protective behavior. He doesn't want to lose Merlin, whether it's due to magical threats or political enemies.
In Merlin Arthur friendship fanfiction, a prevalent theme is sacrifice. Merlin is often willing to sacrifice his own safety and even his secret of magic for Arthur's well - being. Also, the theme of discovery is common. As their friendship progresses, Arthur discovers more about Merlin's true self and abilities, and Merlin discovers more about what it means to be a friend to a future king. There is also the theme of trust, which is constantly tested and strengthened throughout their adventures together.