Merlin AU: Morgana captures Merlin, and makes an enchanted thread that serves as Merlin’s lifeline. When Arthur receives it anonymously, he thinks it may be a clue to getting Merlin back. But what doesn’t know is that every time it’s pulled, it causes Merlin terrible pain. If it’s unraveled, Merlin dies.
"Have you ever had your life hanging by a single thread? Your life is now just that, and it rests in his hands, Merlin. And he doesn’t even know. Let’s see how good it feels when your beloved Arthur is slowly killing you.”