Betrayal is also frequent. Whether it's being betrayed by a friend or someone he loves, it adds a lot of sadness to the story. Like when a trusted ally turns against him because of his magic. It really tugs at the heartstrings.
One sad Merlin fanfiction is 'The Fallen Knight'. It shows Merlin in a state of despair after Arthur's death, and how he struggles to find a new purpose in a world without his king. It's really heart - wrenching.
Well, 'Merlin's Broken Heart' is another one. It focuses on a situation where Merlin is betrayed by someone he trusted deeply. The pain and sadness in his character are palpable throughout the story, and the author does an excellent job of making the readers experience Merlin's emotional turmoil.
In a more humorous take on the 'Merlin tied to a bed' fanfiction, it could be that Merlin has fallen ill and the overly - protective Gaius has tied him to the bed to make sure he rests. Merlin, being the active person he is, complains constantly. Arthur comes to visit and teases Merlin about finally being still for once. Meanwhile, Merlin tries to convince Arthur to let him loose, promising that he'll be fine. Eventually, Gaius relents and unties Merlin, who then immediately starts bustling around the room.
It could. In many fanfictions where everyone forgets Merlin's birthday, it might end sadly as Merlin feels isolated and unloved. He might have expected at least one person to remember, and when no one does, it could lead to a melancholic conclusion with him feeling deeply disappointed and alone.
If Merlin died in the fanfiction, it could trigger a series of tragic events. The balance of power could tip, and the villains might seize the opportunity to attack. It could also bring out hidden strengths in the remaining characters as they try to cope with the loss.
One more idea is that Merlin is tied to the bed in a dream - like state created by an ancient magic. In this dream world, he is faced with his deepest fears and insecurities. His friends in the real world notice his strange behavior and try to wake him up. Merlin, while in the dream, has to find the source of the magic that is binding him and break free. Through his inner strength and the memories of his friends, he manages to do so and wakes up, having learned more about himself and his magic.
If Merlin is a Dark Lord in fanfiction, it could be an interesting exploration of the 'nature vs. nurture' concept. Maybe he turned dark because of the constant fear of being discovered and persecuted for his magic. His actions as a Dark Lord might include taking over Camelot or exacting revenge on those who wronged him in the past. It gives a whole new perspective on his character.