Summary: When Sarah unwittingly releases a malevolent power from an ancient isle, she must join forces with her former adversary to save the kingdom she once threw down. But an alliance with the Goblin King comes with its own dangers, and promises can be perilous...

Author's Note: So... this happened. You can blame (or thank) the channel that decided to show Labyrinth over the Christmas break. Now this thing is already 30,000+ words. And counting. Ye gods. I always said that one day I would write a full-length Labyrinth fic, so I guess this is it.

THE DIAMOND OF THE DAY

Prologue

The cool night air ghosted over his bare skin, stirring the wild strands of pale hair around his face. The tower room commanded a wide view of the Labyrinth, which from such a great height appeared like a pendant nestled in the hollow of a throat, fine-veined threads weaving intricate pathways of illusion and bewilderment to the city at its centre. But it was the view inside that absorbed him. A path of silver moonlight illuminated the chamber, casting its transient glow over the runes carved into the stone-work, tracing a path along the small table upon which sat a solitary crystal and finally falling upon the large bed that was framed by a great pair of horns that supported the elaborate headboard. Carvings of figures cavorting, of faces beautiful and grotesque that gazed down upon the sleeper in silent watchfulness.

Reclining against the stone pillar of the wide tower window, he toyed lazily with the goblet of wine between his long fingers. The deep purple flavour was rich and spiced and potent, but still not a strong enough vintage to drown the taste of her that lingered on his tongue. The Goblin King smiled. His eyes ran appreciatively over the feminine form that lay supine on the tousled silks. Lush curves and slender waist, the violet bloom of bruises unfurling on her white shoulders and throat where he had marked her with lips and teeth. Not that she had minded. Not that she had begged him not to stop. She was ever hungering, ambitious, insatiable. One day it would prove to be her undoing. But the Goblin King did not allow himself to care about such things. There was no tenderness between them - no, never that - only moments of calm between the storms.

The moonlight glimmered in her black hair, those sharp green eyes for once heavy and languid. Mortal, yes. But also something more. She had been touched by the Underground now and would never be ordinary again. But for the present, sated and at ease, her demeanour possessed the softness of almost any human woman. How much easier things would be if she stopped fighting him, he mused idly. And how much less interesting.

Jareth laughed. "Can it be that you are finally satisfied, Morgan?"

Morgan le Fay sat upright at once, casting her heavy hair back over her shoulders. "A bargain is a bargain. I gave you what you wanted."

"And so easily you gave it, too." His tone was soft, mocking.

"You promised," she said. "Show me."

"Very well."

Naked, he walked over to the bed and seated himself behind her, hands curling around her shoulders, sliding down her arms to rest upon her splayed-out fingers. He lowered his lips to the nape of her neck, breathing in the scent of her. Night air and belladonna and the whisper of burnt embers in a dark forest. Witchery and poison. The air shimmered and it was not of his making.

"Your power has grown since we last met."

"You are not my only teacher."

For a moment, Jareth felt a flash of raw jealousy, before a derisive smile curled his lips.

"Nimue?"

"She sends her regards."

"She would do better not to attract my attention." In his voice was the silken dagger of a threat. He needed no reminders of past failures. Nimue had caught him at unawares - a fatal oversight on his part - and it was the closest he had come to ever being overpowered. The pain of death could have been endured, but imprisonment brought only humiliation. He was still young in the reckoning of his kind, but a lesson had been learned. The Labyrinth was his domain and seeking to exert his power too much in the world Above weakened him. His was a face that would never age, but a shadow of experience now haunted his irregular eyes that would never again possess quite the same gleam of vanity that had defined his youth.

The Goblin King shook away such dark ruminations. He turned his attention to the woman in front of him.

"Close your eyes."

She did so, leaning back into the cage of his body. Lust immediately spiked within him, which was no doubt her intent.

"Crystals," he murmured against her hair, "Are formed of dreams, fantasies, desires. Conjure up the image in your mind, so clearly you could almost touch it. That thing you desire most - where the very yearning of it torments your nights and robs your days of all joy. When all else fades to a distant shadow and there is only the consuming hunger. Let it grow, take shape…"

First it was nothing more than a glimmer. Then the clear liquid light took form and hardened into a transparent globe, a sphere, a crystal that danced on the tips of her fingers. A face gradually appeared in its depths, a fair young face, brave and handsome with a sweep of golden hair on his lofty brow where there rested -

Morgan's voice was hard, full of such venom that the figure in the crystal turned to look at her curiously. "Arthur has been crowned King of Camelot."

Jareth shrugged, carelessly. "And what is that to me?"

He felt her shoulders stiffen. "I mean to take what is mine. They cheered him. I stood in the crowd and watched as they cheered him when he took my throne. A mere boy - callow and inexperienced, raised as a commoner. What does he know of power, or rule, or -"

The crystal dropped to the floor and smashed. The fragments of dust shivered across the stone until they vanished altogether under the indifferent sweep of the Goblin King's hand.

"So much power," he chided mockingly, "And so little control."

Furious, she spun around in the circle of his arms and tried to strike him.

With inhuman speed, he caught her wrist. He let forth his power and it snaked over her skin in winding tendrils. He saw her face contort with pain but not a sound escaped her lips. No, she would never show vulnerability in front of him.

There was the warning of danger in the tilt of his chin, the unsmiling mirth that tugged at his thin mouth. "You grow arrogant, Morgan. Do not forget who holds the real power here."

Instead of being cowed, her eyes darkened with something fierce and wild. "Then show me."

"If that is your desire."

He descended on her with elemental fury. It was a warring of teeth and tongues, her nails scoring the pale skin of his back as he hissed against her bared throat. Her limber body writhed beneath his with serpentine grace as he ran a possessive hand down the length of her. How vicious she was, how intoxicating. She was dangerous, he knew. And one day would be even more so, when she came to the zenith of her sorcery. We both of us are dangerous. The Goblin King was not such a fool to think it was him she loved; no, if it came to a choice between him and the power she craved, she had made that choice long ago. It would end in fire and destruction, of course, but in the meantime, both had their uses for one another. And why not take pleasure in the moment while it lasted?

"Tell me," she panted, "Tell me I am your heart's desire - that you would never leave me for another -"

Jareth only laughed. "Who else would there be?" His long fingers threaded through the midnight strands of her hair as he stared into the crystalline depths of her green eyes. There was nothing soft or gentle in her beauty: it was fierce, striking, otherworldly. A face that would lure lesser beings to their doom. My wicked enchantress…

His whisper echoed around the chamber like a challenge, those soft cadences drifting out the open window into the vastness of the sprawling Labyrinth beyond. "Who else could possibly compare?"