Well, in some fanfictions, Merlin is forced to marry Arthur because of a prophecy. The prophecy states that their union will bring great prosperity to Camelot. So, the court and the people push for the marriage despite Merlin's initial reluctance. Or perhaps there's a situation where Merlin has to marry Arthur to save his own life. Maybe he has made a deal with a dark force and the only way out is to marry Arthur.
One possible plot could be that Merlin has some hidden magical ability that makes him a valuable asset in a political marriage to Arthur. For example, his magic could be the key to uniting two kingdoms. Another plot might involve a magical curse that forces the marriage. A third idea could be that Merlin and Arthur are tricked into a marriage by an evil sorcerer who wants to disrupt Camelot from within.
In a fanfiction scenario where Merlin is forced to marry Arthur, it could start with a misunderstanding. The kingdoms believe that Merlin has some sort of claim to the throne through a long - lost lineage. To solidify the power structure, they demand the marriage. This could lead to a lot of internal conflict for both Merlin and Arthur. Merlin is worried about his secret magic being exposed, and Arthur is grappling with his feelings for Merlin as a friend and now as a potential spouse. As the story progresses, they might start to understand each other on a deeper level and actually fall in love despite the forced nature of their union.
Merlin would probably be very conflicted. On one hand, he is loyal to Arthur and Camelot, but on the other, being forced into a marriage is a huge infringement on his freedom. He might be scared about how this will change his life and his ability to use his magic secretly. Arthur, on the other hand, could be initially resistant as well. He sees Merlin as a friend and a servant, and this sudden change to a marital relationship would be strange for him.
Well, one plot could be them facing challenges together as a couple in Camelot. Maybe there are court nobles who oppose their relationship, and they have to fight for their love while also maintaining the kingdom's stability. Another could be Merlin using his magic in new ways to protect Arthur, not just as his friend and advisor but as his husband.
Maybe a plot where Arthur and the knights get a glimpse into Merlin's past through some magical artifact. They see his early days of learning magic and the struggles he faced, which makes them understand his motives and loyalty better. This could lead to a stronger bond between them all.
One possible plot could be that Naruto is forced to marry a character from another village as a political alliance. This would create a lot of drama as he has to adjust to living with someone he barely knows while also dealing with the reactions from his friends in Konoha.
One interesting plot can be found in 'Courting the Warlock'. Here, Arthur starts courting Merlin after realizing that Merlin's magic can be a great asset to Camelot. But as he courts Merlin, he truly falls in love, not just for the magic. This creates a complex dynamic as Merlin is initially suspicious of Arthur's motives. Also, in 'The Royal Courtship', the plot involves Arthur trying to court Merlin while also having to deal with political unrest in Camelot. He has to balance his love for Merlin with his responsibilities as a king - to - be, which makes for a very engaging story.
One interesting Merlin and Arthur fanfiction could be where Merlin reveals his magic to Arthur in a very unexpected and comical way. For example, during a royal banquet, when a knight accidentally drops a sword that's about to impale Arthur, Merlin freezes time and casually walks over to pick up the sword, then unfreezes time and acts like nothing happened. Arthur is left completely bewildered until Merlin finally confesses his powers.
One interesting plotline could be Merlin using his magic in modern times to secretly protect Arthur, who is a powerful businessman or politician. For example, he might use magic to prevent assassination attempts on Arthur.
One interesting story could be where Merlin uses his magic in subtle ways to tease Arthur during their adventures. For example, he might make Arthur's sword just out of reach for a moment, only to have it magically appear in his hand seconds later, leaving Arthur both frustrated and amused at Merlin's antics.
One interesting scenario could be that Arthur plans an elaborate proposal in a secret, enchanted garden. He decorates it with magical lights and rare flowers. Another could be that he proposes during a grand feast, in front of all their friends and allies, making it a very public and joyous occasion. Or perhaps he takes Merlin on a quest, and at the end of it, when they've achieved something great together, he pops the question.
One interesting story could be where Merlin uses his magic to secretly help Arthur court Gwen. For example, he might create small magical moments during their encounters, like making the flowers bloom around them at just the right time. Another could be a story where Gwen discovers Merlin's magic early on and they team up to protect Arthur from various threats.