The banter between Merlin and Arthur in fanfiction is really interesting. It can range from light - hearted jabs at each other's habits. Merlin might poke fun at Arthur's love for jousting and how he always gets a bit too competitive. Arthur could retort by mentioning Merlin's clumsy attempts at serving him. Their banter also reflects the underlying respect they have for each other despite their different social standings. It's like a friendly sparring that keeps their relationship dynamic.
It could start with a slow realization of their feelings. Maybe they were friends for a long time and then suddenly, one day, they look at each other in a new light. After getting married, they become more protective of each other. Arthur might become more open to Merlin's magic, and Merlin would be more involved in Arthur's political decisions.
In fanfiction, Arthur might be rough with Merlin because of a prophecy or a pre - ordained fate. He might think that by being tough on Merlin, he can prevent some bad outcome that he believes is related to Merlin. For example, if there's a prophecy that Merlin will bring great change to Camelot, Arthur might be rough in an attempt to keep things as they are, out of fear of the unknown.
I really like 'The Dragon's Prophecy' in Merlin Arthur fanfiction. It has a lot of action and adventure while still focusing on the relationship between Merlin and Arthur. It shows how Merlin's magic is tied to Arthur's fate in an exciting way. 'Merlin's Secret' is also great as it delves into the secrecy of Merlin's magic and how Arthur slowly discovers it, adding a lot of tension and drama to their relationship.
Merlin might have used his knowledge of the castle's secret passages. He could lead Arthur through those passages, away from the assassins. Also, Merlin could have called upon some magical creatures he's befriended, like the dragon, to help him. The dragon could fly in and either scare the assassins or carry Arthur to safety.
In such fanfictions, Merlin is often portrayed as a very powerful sorceress. She has an air of mystery around her. Her magic is usually depicted as extremely potent and she uses it to protect Arthur or further their shared goals. She might be shown as a manipulator at times, using her intelligence and magic to influence events in their favor.
Gwen also makes for an interesting character in fanfiction. She can be portrayed as a strong - willed woman who supports both Merlin and Arthur. In some stories, she might have a more active role in the magical side of things, perhaps even learning some magic herself to help protect Camelot.
A fanfiction that stands out is 'Arthur and Merlin: A Different Path'. This one takes a different turn from the original storyline. It imagines a world where Arthur discovers Merlin's magic much earlier. This changes the whole dynamic between them, and they face different challenges together. There is also 'The Adventures of Merlin and Arthur in the Enchanted Forest'. It's full of exciting quests and the development of their friendship.
I really like 'A New Beginning'. It features an OC who is a healer. This OC becomes friends with Merlin first and through him, gets involved with Arthur. The story focuses on how the OC uses her healing skills to save Camelot during a plague. It's a really heartwarming story that shows the relationship between the OC, Merlin, and Arthur in a very positive light.
One great 'Arthur Courting Merlin' fanfiction is 'The Courtship of Merlin'. It beautifully depicts Arthur slowly realizing his feelings for Merlin and his clumsy yet endearing attempts at courting. Another is 'Merlin's Heart', which shows how Arthur overcomes the social barriers of being a prince to court Merlin in secret.