When Merlin had first come home, barely able talk or eat and with a steel bar piercing his tongue, Arthur was torn between sympathy, shock, and a fervent desire to time-travel. When Merlin had stood there in their kitchen, tongue out and steel bar glinting in the light, Arthur had been struck with a gut-clenching desire to hold Merlin down and fuck his mouth until his cock was sore from rubbing against Merlin's tongue ring.
Between his desire to have Merlin's tongue on him and Merlin's insistence that they lay off oral sex until the piercing was healed, Arthur had spent every night for eight weeks burying himself in Merlin's ass, fucking into him over and over as he tried to slake the lust that made his blood boil every time Merlin laughed and his tongue ring flashed. Or when he caught Merlin in the bathroom mirror, examining his ring and cleaning it. Or when he caught Merlin's mouth twitching in a strange way and he knew that Merlin was playing with metal in his mouth.
Arthur had endured two whole months of almost constant and insatiable arousal and when Merlin had returned from the piercing parlour, Arthur had grabbed him and dragged him towards the bedroom before Merlin's seductive smile had reached its full magnitude. Then he spent the entire night plunging his cock into Merlin's mouth over and over and groaning at the new sensations, practically weeping at how good it felt and growing hard every time he kissed Merlin afterwards and tasted his own cum in Merlin's mouth, along with the slight tang of steel. Arthur had stayed away long into the night, recounting the experience, his cock twitching feebly in an attempt to harden again, and thinking to himself that no feeling could ever compare.
And then, three months later, Merlin had left the house on his day off and come back two hours later, limping slightly and with a huge grin plastered on his face. Arthur had looked at him with a confused look on his face, mildly concerned until Merlin had opened his belt and dropped his pants to reveal a small bar of steel running through the underside of his cock, just near the crown. Arthur's gaze had turned predatory, and then frustrated, his desire tainted by the knowledge of how long he would have to wait. Then Merlin had just said "two weeks" and Arthur could have wept with joy and frustration all at once. Every night for two weeks, Arthur had Merlin fuck him with his tongue, fingers, and every toy that they had, and Arthur had begged for more and prayed that the days would pass faster.
On day fourteen, Merlin had come home from work to find Arthur naked in the living room, stretching himself open with slick fingers, his face and chest flushed to match his cock which was rock hard against his stomach. Merlin had closed the door behind him and Arthur was on his a second later, fumbling him out of his clothes, his normally capable fingers clumsy with lust. He had pushed Merlin to the ground right there by the door, rolled a condom over Merlin's cock and ridden him, hard and fast until tears ran down his cheeks and his thighs gave out with the strain. Then Merlin had rolled him over and pounded into him over and over until Arthur spilled over his own chest and neck, his cock untouched and his vision marred by blinding white.
Afterwards, as Arthur drifted off to sleep right there on the floor, he thought to himself that no feeling could ever compared and silently dared Merlin to prove him wrong.