Disclaimer: Arda and its creatures are not mine. Neither are the Aliens (shudders). However, I think I've spotted Isilme napping on my bed…

Incubus

"Far, far below the deepest delving of the Dwarves, the world is gnawed by nameless things. Even Sauron knows them not. They are older than he."

- The Two Towers, LoTR Book 3, Ch 5, The White Rider

Prologue: In the Deep

"Too deep we delved there, and woke the nameless fear."

- The Lord of the Rings 2 – The Council of Elrond

- - -

Mid February, Year 41 of the Fourth Age

Somewhere beneath Ered Lithui

"Another wasted day! Whoever claimed that there's silver beneath these forsaken mountains was a fool!"

Thrain, son of Torin, glanced askance at his companion. Kíli, son of Lâr, had many good traits – his careless tongue not one of them.

"Wherever the King of the glittering Caves commands me, I go." Thrain felt the wall with his right hand, sensing the texture of the limestone around them. Despite his disrespectful comments, Kíli had a point: there was no silver to be found here.

Perhaps we should get back," said Kíli. "I heard rumors that Bifin caught a wild boar this morning, and it's been weeks since I tasted anything as good, served with ale."

Thrain sighed and secured his hatchet at his leather belt. "Fine, Kíli." They might as well head back – they had been underground since morning and a mug of ale did sound good.

Both lads made their way to the shaft leading above ground, passing several openings on the walls around them leading deeper. The echoes of steel hitting stone reached their ears, the comforting sound of the earth's heartbeat. In the stillness of the tunnels they crossed paths with other miners, exchanging brief greetings. They had almost reached the shaft when another of their companions stumbled upon them, his round face beaming with excitement.

"It's – it's incredible!"

"Easy, Barin," said Thrain, helping the other Dwarf to steady himself. "Catch your breath and tell us what happened."

Still panting, Barin pointed at a tunnel leading southwards. "Master Nóli's team discovered an ancient door engraved with words in an ancient tongue. Some form of elvish, they said, and the cavern before the door is littered with orcs' bones. They are trying to break through as we speak. Come!"

Barin started to run southwards, and Kíli followed his heel. After a moment of hesitation, so did Thrain. "Wait for me," he cried, his heart pounding inside his chest with excitement. The fleeting thought that what the elves had sealed should not be unleashed crossed his young mind, but he pushed his childish fears back. They had defeated the Dark Lord, had they not? Had not Evil perished, now the stuff of frightening winter tales around the fire?

The remnants of his fears vanished when he stood in the cavern before the door, its surface illuminated by several torches. High, sturdy, of aged oak and iron, the double doors towered over the heads of his comrades. Stretching his neck, Thrain caught glimpse of the Master Mason's form crouched by the door. His skillful hands sensed the wood, feeling the countless winters of silence it had endured in this forsaken place. Slowly, tenderly, the aged Dwarf traced the patterns of iron and the streaks of wood, seeking the secrets of this gate. Breathless – speechless – the assembled miners watched him as he rose and pointed at a spot where wood and metal met.

"Here," he said, his voice a hint of thunder.

Another Dwarf stepped forward, bare-chested, wielding a massive hammer: Master Nóli, one of the most experienced miners, whose team had found this gate. Hefting his hammer, he took a step backwards and managed a powerful blow on the gate. Like thunder the blow echoed through caverns and tunnels in the starless night of the deep. Had the soil beneath their feet trembled? Had a sigh followed the blow, a sigh of a thousand deaths? Thrain felt a shiver down his spine and lowered his eyes with shame for his trepidation. Then he looked up again, as the others around him took a step forward as Master Nóli pushed the gates open. Someone handed him a torch and he cast light to whatever lay behind the door.

Once more, Thrain stretched his neck to get a better glimpse. A vast cavern lay behind the gate, and the smell of humid, stale air reached his nostrils. As the other miners before him walked forward, Thrain followed, looking agape at the multicolored stalagmites and stalactites. The sparkled green and blue and yellow, and the sound of dripping water echoed around him in the vastness of the cave. Still, the seeds of doubt spoiled the magnificent sight around him; why had the elves sealed this place?

"Master Nóli!"

Kíli's voice made him focus, the icy fingers of terror gripping his heart anew. Something is wrong here. Just as he picked up his pace, Kíli called out again.

"Master Nóli! You must see this!"

Thrain reached the edge of a shallow pool, and found Kíli standing in the clear water up to his ankles. The strangest of things lay in the middle of the pool on a flat stone, barely above the water surface: an egg like nothing he had ever seen.

"Look what I've found," said Kíli and cocked his head, his voice quivering with pride. "It's a dragon's egg."

"Lad, get out of there," said an old Dwarf beside him, and Thrain turned his head to see Delin, the Master Mason, right next to him. With his brow furrowed over eyes focused and unblinking, his stare darted from Kíli to the strange egg. "This is no dragon's egg."

Kíli pouted. "What else can it be?" He raised his hoe and poked the egg.

"Lad, get out of there. This place was sealed for a reason." The concern in the old Dwarf's voice made Thrain's stomach churn.

Kíli continued to poke the egg, whose leathery surface throbbed in the most unsettling manner.

"By Smaug's backbone, lad, leave that egg al –"

Delin had hardly finished his words when the top of the egg opened. In a moment that seemed to linger on, Thrain watched his friend lean over the opening to peek inside. His dry throat closed on the warning cry he never voiced, when a foul creature, propelled by a muscular tail, leaped out of the egg and covered Kíli's face. Writhing, with his arms waving aimlessly around, Kíli fell back and lay still in the deafening silence of the cave.

After a moment of shock, the Master Mason and Master Nóli leaped inside the pool. Delin shoved a torch inside the egg while Master Nóli picked up Kíli and carried him out. Thrain watched in horror the arachnid creature that clung on his friend's face.

"Kíli…" he mumbled, still petrified. "All he wanted was a juicy piece of wild boar and a mug of ale." His head jerked sideways as a strong hand gripped his shoulder.

"Take heart, lad," the Master Mason said. "Your friend will be fine."

Yet his eyes spoke his doubt.

- - -

A bat flew up the shaft and into the night air and screeched in its own tongue the tale of the deep. The owls heard it and flew west and south, bearers of ill news.

Later that night, in a stable somewhere in Pelargir, a white tomcat heard the cry of the owl, and stirred in his sleep. Stretching his forelegs in a lazy, languid motion, he blinked his amber eyes – eyes that saw all the things that men wish most to keep hidden. Yawning, he stood and leaped on the stable's window, staring into the night.

His eyes darted back and forth, between his warm, cosy spot on the straw and the north and the evil that lurked there. After a moment of contemplation, Isilme leaped on the ground and took the path to the north, mumbling curses in High Feline about mortals and their stupidity.

There should better be some fat rats in those caves.

- - -

Isilme: Moonlight in Sindarin.

All the things that men wish most to keep hidden: Reference to Queen Berúthiel's cats. In case you hadn't already guessed, Isilme is a descendant of those cats.

Why cats? Well, what did you expect from me? Anyway, in the first Alien film, the only creature that looked the Alien in the eye and lived to tell the tale was that ginger tomcat, Jonesy. It's only fitting that a cat should be in this tale.

If you spot any holes with LotR canon, please let me know. Including Dwarven names…

Inspiration for the title came from a 2000 AD graphic Novel.