It isn’t anything big that draws his attention to it, nothing specific, but Merlin just has this— inclination, this off feeling when he stops and thinks about it long enough.
It’s in the slant of his mouth, the hard steel-glint of his eyes, and the way his hands feel on Merlin’s skin: harder, rougher. Possessive.
Now that Merlin’s seen it, he can’t unsee it: can’t pretend that the man that walked out of the lake is the same one he reverently placed in a boat and set adrift.
Can’t deny the fact that the man he loves came back different.
When the first body turns up, Merlin doesn’t think anything of it; he doesn’t even recognise the bloke until the news report says he’d been found outside the hospital where he used to work. Merlin remembers then: he was the nurse who turned Merlin away from visiting his mum, saying it was outside visiting hours.
“You didn’t hurt him, did you?” Merlin asks, not expecting an answer.
“I didn’t like the way he talked to you,” Arthur says, and Merlin tries to tamp down the sick feeling in his stomach.
When Merlin is fired from his job at the garden centre, his boss turns up a week later, his neck snapped and Merlin just knows the hands that snapped that neck are the ones that touch him every night.
“You can’t keep doing this, Arthur,” Merlin says, fear coiled tight in his lungs.
“I know.” Arthur bows his head and he looks like a child. “I just have these feelings. I get so angry that I can’t help myself— I don’t know what’s happening to me, Merlin.”
Merlin tries not to cry when Arthur clings to him, his face pressed into his neck and whispers, “I’ve just missed you so much.”
When the woman from Number 8, who called Merlin a creepy little faggot gets discovered in her bedroom, smothered by a pillow, Merlin has no choice but to act.
“What do I have to do?” Merlin asks, “to make you stop?”
“I don’t know,” Arthur says, and he sounds so lost that Merlin has to reach out and lay a hand on Arthur’s cheek, stroke his cheekbone with his thumb. He realises he isn’t scared of him, he’s scared for him and that’s quite a distinction.
“If you hurt me—” Merlin says, “would that help?”
Arthur reels back like he’s been shot. “I could never hurt you,” he says. “Never.”
“But what if I let you?” Merlin asks. “What then?”
He grabs Arthur’s hand and places it on his throat. Arthur’s eyes widen in horror and he pulls it away. Merlin just smiles. “It’s okay,” Merlin says, “I can stop you if it goes too far. Magic, remember?”
Merlin leads Arthur to the bed and they kiss: open-mouthed, obscene. Merlin strips his clothes off, only pausing the kiss to pull his t-shirt over his head. He unzips Arthur’s jeans, pushes his underwear aside and rides him slowly, Arthur’s cock driving deep inside him.
When Arthur’s hand wraps around his throat, Merlin isn’t the least bit frightened. He pushes forward and groans when Arthur’s thumb presses into his carotid.
“You like this?” Arthur asks, awed.
“I like you,” Merlin says, “I love you. This is killing you, Arthur. So do it.”
Arthur digs his fingers in and holds Merlin tight around the throat while Merlin fucks himself on Arthur’s cock. When Merlin comes, he can’t breathe for a minute. Sparks dance in front of his eyes and Arthur flips them over, works himself deep into Merlin’s body.
When Arthur comes deep inside Merlin, his hand still wrapped around Merlin’s throat, he looks like himself again, beautiful and unattainable and golden.
Merlin has finger-shaped bruises around his throat like a necklace, and Arthur digs into them with his thumbs and whispers, “Thank you. I thought maybe you’d make me leave.”
Merlin shakes his head and kisses Arthur once, a quick brush of lips. “Never. You’re never leaving me again.”
When the waiter at dinner a week later looks down his nose at Merlin, and Arthur looks homicidal, Merlin placates him with a hand on his leg. Later, he lets Arthur tie him to the bed and bring him to the edge over and over again, scratching and biting so hard he breaks skin.
Arthur whispers apologies into his skin afterwards, his tongue soothing, and Merlin wears his marks as if they were the Pendragon crest.