Chapter Text
Merlin sighed as he shifted uncomfortably atop his horse. The aging spell Arthur had asked him to perform on them both was having some unforeseen consequences. Initially he had thought Arthur’s idea to age him up had been brilliant—they needed information and it was the perfect disguise. He hadn’t been as keen about the part where he was supposed to regress his own age a few years back though. It was so the two would make a convincing father and son, he had gone along with it because it was a smart plan.
Unfortunately, that meant that he was now sitting astride a horse, in a horny teenage body, watching Arthur’s shirt stretch tight across his very fit and much broader shoulders under the hot sun. Each time Arthur lifted his shirt to let the air circulate Merlin would catch tantalizing glimpses of skin and the swell of his ass pressed flush to the back of the horse.
Which had led to the currently very big, very hard problem in his pants. A problem which he doubted Arthur would be inclined to take care of until they were safely back in the Citadel and the spell had been lifted from them both. Which was, in Merlin’s opinion, a damn shame because this older version of Arthur was doing things to Merlin. He decided they were definitely going to be exploring that thought further sometime in the near future. But for now, just thinking about it was making Merlin’s very horny, teenage cock spasm in want, pressing it harshly against his rapidly tightening trousers.
Once again, Merlin shifted, pressing a hand to his cock in a vain attempt to bring himself some relief.
“What are you doing back there, Mer-lin?”
Arthur’s voice interrupted his erotic musings, bringing his head up with a start as he tried to hide both his hard cock and his guilty hand from Arthur’s keen gaze.
“Nothing!” He answered guiltily as Arthur’s eyes bored into him.
“Oh really?” Arthur asked as he turned his horse around and brought it flush with Merlin’s.
“That doesn’t look like nothing to me,” he smirked, his eyes flicking pointedly to Merlin’s crotch, which gave an answering twitch. Damn Arthur and his stupid lips, and his own stupid cock, which definitely seemed to like obeying Arthur more than him. They were going to have words in the near future damn it!
“Oh, I’m sorry Daddy. I just seem to be having some problems with these damn teenage hormones!” Merlin snapped.
Arthur took in a sharp breath, his eyes dilating, as he shifted suddenly on his horse. Merlin looked down in surprise to see Arthur’s cock swelling slightly in his trousers as well. A smile grew on Merlin’s face at the sight.
“Oh, you like that, do you Daddy?” Merlin smirked at Arthur. Noting the way his hands clenched around his horse’s reigns before he turned the horse abruptly and set a brisk pace. Merlin hurried to follow on his horse, wondering if he had upset Arthur after all.
A few minutes later he noticed with a sense of relief that Arthur was turning off the road up ahead and making his way to a clearing hidden back a ways from the path. There he quickly dismounted and began attending to his horse.
“We’re going to set up camp here,” he told Merlin, his voice hoarse with need.
“But it’s still early yet,” Merlin protested. “We can still easily make it back to Camelot tonight.”
Suddenly Arthur was towering over Merlin. “Don’t you want to please your Daddy?” he purred.
The sudden desire that ripped through Merlin at those words robbed him of the ability to breathe, let alone speak. He nodded mutely up at Arthur as he tried to catch his breath.
“Good,” Arthur responded, pleased. He lifted a hand to stroke Merlin’s hair. “Set up camp while I take care of the horses; and be quick so Daddy can take care of his little boy.
With that Arthur turned to attend to the horses, while Merlin set the camp up in record time. When he was done he stood awkwardly next to Arthur, waiting for him to tell him what to do next.
“There’s a lake just down the hill there where we can get cleaned up,” Arthur told him. “Come on, Daddy wants to make sure you’re nice and clean.”
“I thought my Daddy wanted me to be a dirty boy though,” Merlin teased.
“Oh, I do,” Arthur agreed. “But I need to get my boy all clean, so Daddy can dirty you up properly.”
He gave Merlin a leering grin as he dragged him down to the water and helped him undress.
“You’re so much smaller like this,” Arthur observed as his hands trailed over Merlin’s neck and down his chest. He tentatively reached out his fingertips to graze lightly over Merlin’s stiff, but obviously smaller cock, before wrapping his large hand around him, engulfing it within.
“You’re also quite a bit bigger too you know,” Merlin retorted, the observation stinging his modest, yet still present ego. “I’m not that small.”
“No, you’re not, you’re perfect,” Arthur breathed, taking his hand and leading him into the water. The cool water felt refreshing against his skin as his Daddy helped wash the dirt and grime of the road from him. His large hands attentive as they bathed his little boy. Merlin helped to wash his Daddy in turn, marveling at how large Arthur was and what he had to look forward to for years to come.
His cock, long denied, was heavy and red between his legs as they worked. Twitching in anticipation when Arthur’s hard body pressed against his, as his Daddy’s large hands rubbed down every inch of him. Merlin wasn’t sure how much more of this he could take, but Daddy had promised to take care of him, so all he could do was wait.
Once they were both clean they walked hand in hand back to camp where Arthur—no, his Daddy he reminded himself—lowered him to the bedrolls laying flush together, side-by-side. Daddy then crawled over him, dwarfing Merlin’s smaller body with his own. He blocked out the sun as he took Merlin’s lips in a gentle but deep kiss. In that moment his Daddy became his entire world.
Merlin drew in a ragged gasp as his Daddy moved to suck at his neck, then his nipples before leaving a hot, wet trail down to his cock.
“You’re so beautiful baby,” his Daddy marveled, placing a few sweet kisses on Merlin’s dick. He licked teasingly at the slit, sucking the pre-cum up with a moan before swallowing Merlin down.
Oh god, there were definitely some advantages to being smaller, Merlin thought desperately as he was engulfed by the hot, wet heat of Arthur’s mouth. Arthur’s throat constricted around his cock as he swallowed, turning Merlin into a moaning, writhing mess beneath him. Arthur then lifted up to tongue the head some more, dipping into his slit to lick up more of the pre-cum pooling there before plunging back down again.
He wished he could prolong the moment, but he couldn’t wait any longer. The stimulation was too much. He tried to warn Arthur but his Daddy, sensing he was close, picked up the pace. He sucked frantically on his cock, moaning around him when Merlin canted his hips into the air, trying to drive his dick deeper into Arthur’s hot mouth. Arthur’s hands reached around and grabbed onto his ass, his fingers digging into the flesh as he fucked his face with Merlin’s cock.
Merlin couldn’t take it anymore, he was so close, so close—he was there! The world went white as wave, after wave of pleasure coursed through him. His cock spurting streams of cum down his Daddy’s throat which his Daddy swallowed up greedily.
He came back to himself as his Daddy was sucking and licking his softening cock gently, making sure his baby was completely clean. Merlin gazed down on his Daddy with a lazy, satisfied smile which Arthur returned.
“There. Didn’t I say Daddy would take good care of his baby?”