Dragon Pr0n for you, my dear!
"Have you ever had fire sex, Potter?"
Harry roused, eyelids heavy, though he hadn't been napping. He never napped, no matter what Severus said. It was simply nice to sit by the fire and close one's eyes after a busy day and a delicious meal made by Kreacher's successor, Ribbly. "What do you mean? On the rug?" He eyed it dubiously. "I think I could do it, but your back – "
"Not in front of the fire." Severus snorted. "Really. Do you think I'm a fool? The only way I'll ever have rug sex again is if you decide to dump me on the hearth and indulge in necrophilia once I'm gone." He snorted again and shook his head, his white hair glinting in the firelight. "Idiot. No. Fire sex."
"Never heard of it." Harry hefted himself straight in his chair, ignoring the creak of his bad hip, and looked at Severus suspiciously. "You wouldn't be taking the piss, would you?"
Severus huffed and turned away from him, his wand drawn. The fire flared as he moved the wand in an intricate pattern, a golden flame separating itself from the rest and twisting out of the hearth to hover in front of him. It took the form of a dragon, one with a long, sinuous neck and a graceful tail crackling with silver sparks.
"Cor," Harry breathed. It was beautiful. He fumbled for his wand. "What's the incantation?"
"Incendia somes," Severus whispered. His dragon waited until Harry's, a crimson red creature with delicate wings, joined it. They hovered between Harry and Severus.
"I can feel it," Harry said. The flame in front of him seemed to flicker across his skin. Experimentally, he put his wand aside and raised a hand. A crimson wing fluttered and warmth began to pool in his groin. "Oh."
Severus smirked. He gestured, and his dragon twined with Harry's. Harry gasped.
"Oh, God, Severus," he whispered. He watched the golden dragon caress his crimson one; he could feel Severus's fingers brush against him, though Severus remained in his chair, across the hearth from Harry. "D'you…?"
Severus's eyes burned. "Yes." He shivered as Harry's dragon returned the caress.
The dragons began to twist and chase one another in graceful swirls of flame and heat, their antics burning across Harry's body. His bad hip kept him from thrusting – had done for years, now – but as his dragon mounted Severus's and enfolded it in its wings, its sinuous movements spurred body memories of Severus's tight heat around his cock, the snap of his hips against Severus's arse, the desperate way Severus used to push back against him, snarling and ordering him to fuck deeper, harder and it was as if they were once again together like that instead of their careful, loving hand jobs and gentle sucking. He watched Severus's face bead with sweat, his chest heave, his expression become fixed and heated as their eyes met over the frantic movements of the flame-dragons.
His orgasm, when it hit, never seemed to end. "Severus," he gasped. "Oh, God, yes!"
Severus's pupils dilated further, then he gasped in turn, silent as always in orgasm.
Panting heavily, they watched as the flames flickered and disappeared, leaving two sated old men sitting in comfortable chairs by a cosy fire, trousers damp.
"We've still got it," Harry finally said. He smiled at Severus, who smirked back. In the firelight, Harry could almost see his sardonic Potions professor, regardless of the silvered hair and the deep lines etching Severus's face.
He wondered if Severus saw the black-haired, defiant brat that still lived inside Harry.