a/n Thanks to MssDare for the pre-read. This is unbeta'd so I apologise for any errors. (Written for the Oral Fixation square on my Kink Bingo card) Enjoy.

Watch Your Mouth

English Lit was even more torturous than usual. Shakespeare was not one of Arthur's favourites to begin with, but today's lesson was the worst so far this term. It wasn't just the subject matter today though, because Arthur was paying scant attention to anything being said around him.

No, Arthur's discomfort was all down to the action of one person, and one person only.

Merlin.

Why Arthur had chosen to sit in this particular seat - which afforded him an uninterrupted view of the 'problem' – he would never know.

Arthur swallowed thickly, eyes following the tip of his boyfriend's pen as it disappeared inside his mouth. A mouth which, Arthur knew from vast experience, was hot and wet and incredibly talented and should definitely be sucking on Arthur's cock instead of that bloody pen!

He loved Merlin's mouth. Loved it and used it at every available opportunity. Merlin was well aware of this obsession and mercilessly taunted Arthur every chance he got. Like now. Merlin sucked the pen further in, his teeth gently worrying the edges and eliciting a low groan from Arthur. Oh God! Arthur clenched his fists under the table and counted to ten in his head. He needed to look away. If he didn't then there was good chance he'd either come in his pants or jump on Merlin and treat the class to different kind of lesson altogether.

Merlin smirked as he slowly withdrew the pen and ran it teasingly along his plump bottom lip.
Through some sort of herculean effort, Arthur managed to resist palming his crotch, even though his dick was straining in his jeans and just about begging for some attention. As far as Arthur was concerned, Merlin had caused this predicament and Merlin could bloody well take care of it too!

They both knew what was going to happen when the bell eventually rang. At least Arthur did, and Merlin had better be on board with the idea too, or he might just have to strangle him.

"Come on, already," he hissed, scowling at the clock and cursing its slow moving hands.

Merlin's soft snicker told Arthur that he hadn't been as quiet as he'd intended. The teacher gave him a disapproving look but the bell rang immediately after, and Arthur wasted no time at all - shoving everything into his bag and practically running out the door.

He waited just outside the classroom, impatient for Merlin to come out.

Arthur started to tap his feet. What was taking so long? If Merlin was doing this on purpose, Arthur was going to kill him. He was already using his book bag to hide the bulge in his jeans; he didn't want to add 'loitering with intent' to his odd behaviour.

Fucking finally, he spotted the familiar mop of black hair strolling through the door.

"What on earth have you been doing in there?" Arthur hissed, grabbing Merlin by the shoulder and dragging him down the hall.

"Why? Were you waiting for me?" Merlin laughed at the murderous look on Arthur's face.

"You know I was bloody well waiting for you!" Arthur muttered, opening the door to the store cupboard and manhandling Merlin inside. "And while I love listening to the ridiculous things that come out of that smart mouth of yours, Merlin. I can think of a much better use for it!"

Arthur shut the door behind them. "I think you owe me," he said, leaning back against it. "Teasing me like that wasn't very nice. Look what you did." He gestured to his crotch.

Merlin licked his lips, grinning as Arthur's eyes tracked every move of his tongue. "What do you want, Arthur?" Merlin whispered, moving closer and running his hands up Arthur's chest. "Do you want my mouth?" he asked. "Do you want me on my knees... sucking your cock until you come, thick and hot down my throat?"

"Oh God...yes!" Arthur rasped, unable to stop his hands from gripping Merlin's shoulders and giving him a gentle shove in the right direction.

Soft laughter spilled out of Merlin as he gave Arthur his widest smile, eyes bright and full of mischief. He pushed up against the pressure of Arthur's hands, just enough to lean forward and whisper in his ear. "Fuck my mouth, Arthur..." Merlin's warm breath ghosted over Arthur's ear. "Make me choke."

A strangled sound escaped Arthur's throat as Merlin sank to his knees, making quick work of Arthur's jeans and boxers. He watched, hands fisted at his sides as Merlin's long fingers wrapped around his prick and brought it towards his pretty, pretty mouth. "Merlin..." Arthur breathed, biting his lip in anticipation. Merlin looked up and Arthur's breath hitched as his tongue flicked out to taste the pre-come leaking out of Arthur's cock.

"Hmm..." Merlin hummed, opening his mouth and sucking Arthur all the way into his throat.

"Holy shit!" Arthur cried out, his hands sliding into Merlin's hair and hanging on
for dear life as Merlin's tongue did things that made Arthur's toes curl and his eyes roll back into his head. This was what Arthur had imagined when he'd watched Merlin fellating his pen. This was why he would let Merlin tease him shamelessly. This... was the reason that Arthur would let Merlin fuck him over his desk when he came round to 'study' after school.

Merlin's lips were red and swollen, stretched wide around Arthur's dick and sucking up and down with his eyes fixed on Arthur's the whole time. Pushing back the need to come at the sight of Merlin like that - looking up at him with such trust and adoration - Arthur stroked his thumb down the side of Merlin's face and along the edges of his lips, forced wide by Arthur's girth.

Merlin closed his eyes, leaning into Arthur's touch. He hummed again, purring like a cat and sending shivers straight up Arthur's spine. Pleasure licked along Arthur's bones, tickling his nerve endings and settling deep in his belly.

"Merlin..." he breathed, wanting to say more but unable to find the words. It was hardly surprising that he was rendered speechless, given the way Merlin was using his tongue and the barest hint of teeth. It was a miracle that Arthur was still standing. He braced himself against the door when firm hands settled on his hips, tugging a little and urging him to move. Too far gone to ask - 'are you sure?' - 'is this ok?", Arthur fisted Merlin's hair once more, and he thrust his dick shamelessly into Merlin's willing mouth.

He felt the tightness of Merlin's throat as he fucked into his mouth again and again, driving Arthur closer to the edge until he was barely holding on. Merlin's fingers dug painfully into the flesh of Arthur's arse cheeks and he managed one more thrust before he was coming, spilling hot and sticky onto Merlin's tongue.

"Fuck..." Arthur gasped out, his hands still buried in Merlin's thick black hair as that perfect mouth of his worked to capture everything and swallow it down. Merlin rocked slowly back onto his heels, letting Arthur's cock slip out of his mouth with a soft kiss to the tip and carefully dragging Arthur's jeans and boxers back up over his hips.

"Come here," Arthur said, drawing in a shaky breath. He pulled Merlin off the floor and kissed him; thrilling at the taste of his cum on Merlin's lips. "Thank you."

"My pleasure," Merlin said, smirking in that filthy way of his.

Arthur glanced down, grinning widely as he spotted the tell-tale wet patch on the front of Merlin's jeans. "So I see."