In many fanfictions, Merlin's magic acts as a catalyst. For example, if Freya is in danger, Merlin uses his magic to protect her. This shows Arthur that there is more to the world of magic than he thought. It can make Arthur more accepting of Freya, who is often associated with magic. Sometimes, Merlin's magic also reveals secrets about Freya that Arthur needs to know, which either brings them closer or causes some initial friction as Arthur has to adjust to new revelations.
In most cases, it initially causes shock and confusion for Arthur. He has grown up believing magic is evil, so seeing Merlin, his closest friend, using it is a huge blow. However, it can also lead to a deeper understanding between them. Arthur realizes that Merlin has been using his magic all this time to protect him and Camelot. This can strengthen their bond as Arthur now sees Merlin in a new light, not just as a servant but as a powerful ally.
Some fanfictions show Arthur becoming more dependent on Merlin's magic in certain situations. For instance, when facing a powerful enemy that can't be defeated by normal means. This changes the dynamic from just a king - servant relationship to more of a partnership. Merlin, on the other hand, might feel more confident in using his magic openly around Arthur, which also alters their interactions. They could have more equal conversations and decision - making processes.
If not resolved, it could lead to a breakdown in their relationship. Merlin's flinching might eventually push Arthur away, making him feel like Merlin doesn't trust him. This could cause Arthur to distance himself from Merlin, which would be a huge change from their usually close bond in most Merlin - Arthur stories.
It completely changes the dynamic. Instead of just a friendship, it adds a layer of romantic love. Their interactions now have a different undertone. For example, a simple glance between them in the original story might just be friendly, but in the fanfiction, it could be filled with passion and love.
Merlin's magic can both strengthen and complicate their relationship. On one hand, his magic allows him to protect Arthur in ways others can't. For example, he can use magic to heal Arthur's wounds secretly. But on the other hand, Merlin has to hide his magic from Arthur in many fanfictions because of the laws against magic in Camelot. This secrecy can create tension, like when Arthur suspects something is different about Merlin but can't quite put his finger on it.
In such a fanfiction scenario, the roughness can have various impacts. It could create a sense of tension and conflict in their relationship. Merlin might start to question Arthur's true feelings towards him. But on the other hand, this rough treatment could also be a sign of Arthur's internal struggles or misunderstandings. Maybe he's dealing with his own insecurities or pressures and taking it out on Merlin in the wrong way. As the story progresses, this could be a catalyst for character growth for both of them, with Merlin learning to stand up for himself and Arthur learning to be more empathetic.
Merlin can impact their relationship positively. He might use his magic to create opportunities for them to be alone, like creating a private garden for their dates.
Fanfiction often explores their relationship in many ways. For example, it can show how Merlin acts as a mediator between Arthur and Gwen. He might use his magic subtly to bring them closer or resolve misunderstandings. Sometimes, it shows how Arthur's sense of duty as king affects his relationship with Gwen, and how Merlin helps him balance that with his personal feelings.
One great 'Merlin Freya Arthur' fanfiction is 'The Lost Bond'. It beautifully weaves the relationship between Merlin, Freya, and Arthur. It shows how Merlin's magic can be a bridge between Freya's otherworldly nature and Arthur's destiny as a king. Another one is 'Freya's Return', which brings Freya back into the story in a very unexpected way and explores how her presence affects the dynamic between Merlin and Arthur. There are also many on fanfiction.net that you can explore based on reviews and ratings.
During the time of Merlin's captivity, they could have long conversations that they never had before. Arthur might open up about his insecurities regarding magic and his kingdom, and Merlin could share his true feelings about serving Arthur. This would strengthen their bond in a new and unexpected way.