One common theme is the struggle against society's norms. Since in the original legend their relationship is not of a married nature, in fanfictions they often have to face opposition from the court or the kingdom. Another theme is the discovery of their true feelings for each other, which might be a slow - burn process even though they end up married.
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.
The 'Redemption' trope is also seen in some fanfictions. Maybe Arthur has made some mistakes in the past, and Merlin helps him to redeem himself. Or vice versa. It's a way to explore the characters' growth and development. And then there's the 'Battle Against Evil' trope where they fight side by side against dark forces, which really showcases their bond and loyalty.
I really like 'The Sword in the Stone' as a fanfiction - like take on Merlin and Arthur. It shows Merlin as this wise and mysterious figure guiding Arthur on his journey to become king. There are also some great interactions between the two characters that show the deep bond they share. You can find it in many libraries or online bookstores.
You can start by looking on Archive of Our Own (AO3). It has a vast collection of fanfictions, and you can simply search for 'Arthur and Merlin married' in the search bar. There are also some fanfiction communities on Tumblr where fans might share their works or recommend good ones.
One way they overcome challenges is by being true to themselves. Arthur, as the king, has to balance his duties to the kingdom with his love for Merlin. He realizes that his love for Merlin doesn't make him a weaker king but a more compassionate one. Merlin, on the other hand, uses his magic not just to protect Arthur but also to show the people of Camelot that he is an asset to the kingdom. Together, they face any rumors or negative talk head - on, and their love for each other only grows stronger through these difficulties.
Their wedding would be a grand affair. It might be held in Camelot's grand hall, filled with knights, nobles, and common folk alike. Arthur would surely wear his finest armor, polished to a shine, while Merlin would don a simple yet elegant robe. There would be feasting for days, with music and dancing. The vows they exchange would be a blend of the traditional and the deeply personal, pledging their love and loyalty to each other in front of all their friends and subjects.
Merlin would likely be seen as a bit of an enigma at Hogwarts. His magic is different from the norm, so he might be a bit of an outsider at first. But his kind heart and loyalty would soon win over his classmates. Arthur would be the brave and headstrong character, perhaps a bit like a Gryffindor version of his usual self. He'd be eager to learn about combat magic and would probably be a natural leader in group projects or Quidditch teams.
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.
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.