Arthur rested his head on Merlin's lower back, catching his breath until Merlin clenched around his softening cock. Arthur hissed, oversensitive, and slipped out.
He’d been planning this for weeks, whispering in Merlin’s ear and watching him flush. As he picked up his creation, his heart thudded at the girth beneath his fingers.
He’d begun with the largest candle he could find in the castle -- the thickness of Arthur’s fist, and the length of his forearm. Slowly, he’d melted the sides to thin it as he liked, tapering it just enough at one end, softening the wax so he could work it, sliding his callused hands over and over until it was polished smooth. Merlin would steal glimpses as he prepared Arthur’s chamber for the night, curiosity plain on his face. Arthur would smirk and shake his head. “Not quite ready yet.”
Merlin's hole was red, loose and wet. Arthur slipped a thumb inside, pumping once and twice. The ring of muscle fluttered and a drip of Arthur’s come trickled out. Arthur groaned, lifting his thumb to his mouth and waiting for Merlin to turn, watch over his shoulder, before he sucked it clean.
He slicked the candle with the vial of oil they’d already half-used, meticulously slow, knowing the anticipation was torture. It glistened in the moonlight filtering through the window, shimmering as if by magic. He lined it up, rubbing the tip in the mess at Merlin’s rim, playing in lazy circles until Merlin’s moans became desperate, breathless.
It'd been weeks of foreplay leading up to this. At night he’d fuck Merlin, hand over Merlin’s mouth, so Merlin could smell the beeswax still clinging to his fingers and know what Arthur had been doing in his spare time. He'd push a finger inside alongside his cock, and tell Merlin how pretty he looked, how full he was going to be. Then he’d watch Merlin’s face go slack, eyes fall shut, nostrils flare as he inhaled the sickly sweet evidence of Arthur’s promise.
But the reality of it was a thousand times better than the teasing. He watched Merlin’s arse swallow the first inch, and Arthur's mouth went dry. At the tip, the candle was roughly the thickness of Arthur’s cock, but the girth increased quickly. Arthur pressed in further and Merlin cried out, his hands clutching the sheets.
“More.” The word tore from Merlin’s throat, raw and visceral. His thighs trembled as the candle sunk deeper, his dick swaying heavily between the wide spread of his legs.
It was more than Arthur had ever expected Merlin to take. He was pulled so wide -- wide like two cocks, wide like a fist or the hilt of a sword. And he was taking it, pushing back for more with strangled gasps of Arthur.
When the marker Arthur had made kissed the taut ring of muscle, Arthur swore, astonished that Merlin had managed it all. He leaned in, licked where the rim and candle met, tasting oil and come and the sweetness of honey comb. He nuzzled and kissed while Merlin went mad with every tiny movement of the candle, every wet lick of his rim.
Arthur sat up, knowing there was one more thing he needed, Merlin needed. He reached for the lit candle on his bedside table. Merlin had lost all awareness, wrecked and whimpering, his eyes glazed over, and Arthur knew he was oblivious to everything but the huge wax cock inside him. The first splash of hot wax on his arse took Merlin by surprise. He arched his back, inhaling a ragged breath. Arthur watched the circle of wax cool and thicken on the sweat-soaked skin. He’d peel them off later, one by one, dragging his teeth along Merlin’s body while Merlin writhed like a wild cat. But he wasn’t done this work of art yet.
He painted the back of Merlin’s thighs, the curve of his spine, his nape. He worked randomly: a small tickle of wax one moment, then nothing for an eternity, mixed with a dozen sloppy splashes until Merlin was entirely incoherent. Finally, a single fat drip on the crack of his arse and Merlin choked Arthur’s name into the pillow and came.
He held Merlin tight, keeping him steady as he spasmed around the candle, then carefully slid the massive wax cock free so Merlin could collapse.
Arthur crawled up the mattress, dancing his fingers along a trail of hardened wax. He whispered, "You're amazing."