A/N: A response to this prompt on kinkme_merlin: Arthur/Merlin, Arthur fucking himself on Merlin's fingers. Lots of dirty talk about how Arthur's so slutty he can't even wait for the real thing will make all of OP's dreams come true!
"Think you can hold still, for once?" Merlin asked, voice rough and low, as he slid the first finger inside Arthur. The prince, for his part, was already completely hard and wanton and desperate, so he just writhed in response as Merlin slid his finger in straight to the knuckle.
He slowly moved his finger in a circular motion, grinning at Arthur's high, keening whine as he did so. Arthur bucked his hips up as soon as Merlin flexed his fingers, and twisted in the sheets when Merlin resumed the circular motions.
"Guess not, then," Merlin said as a second finger joined the first.
Arthur nodded in agreement before promptly jerking right off the bed when Merlin scissored his fingers inside Arthur, smirking at the reaction of the man on his fingers, and scissoring while going in a circular motion, making Arthur undulate his hips deliciously as he tried to push himself more on Merlin.
Feeling rather generous, Merlin simply shoved the third finger in, no warning, no preparation, no ease, and Arthur moaned and whimpered and tried to push himself even further on the little appendages as Merlin kept the fingers scissoring away from each other, stretching Arthur wide open.
"You know, Arthur," Merlin said, conversationally, from between Arthur's propped up legs. "They say patience is a virtue?"
"Wh...what?" he mumbled, eyes screwing shut as Merlin stroked one finger after another after another over his prostrate.
"You're just so...impatient..." Merlin said, the last word coming out as a near moan from himself. "You're so...desperate...to be filled...that you'll fuck...fuck yourself...with my...fingers." And that last word was punctuated with a sharp thrust from Merlin's fingers right up against Arthur's hotspot and a sharp jerk of the hips from Arthur as he came, white ropes of come spraying across his chest and stomach to the accompaniment of a whine that came straight from the back of his throat and went right to Merlin's cock.
Merlin kept up his finger movements, though now softer and gentler, massaging and tender, as Arthur came down off his orgasmic high and lay before Merlin, sprawled across the bed, wanton and sated with a dopey smile on his face.
Above him, Merlin smirked at the objecting whine that came out of Arthur's mouth as he pulled his fingers out.
"Like I said," Merlin said, before thrusting his cock right into Arthur's waiting body in one go, straight to the hilt even as Arthur arched off the bed and desperately offered his entire body to Merlin's touch. "Patience is a virtue."