A/N: Apologies if this has already been done.  It's just a bit of fun, and no offence is intended to any stories in particular :)
Any names you recognize are the creation of J.R.R. Tolkien; anything stupid I happily claim as my own.

The Groupie of Dol Guldur

I

Úlairiel sang to herself as she ambled through the forest of Mirkwood; bits from the Lay of Leithian, mixed in an avant-garde way with what she could remember of the Lay of Nimrodel.  Occasionally she took a pot-shot at one of the black squirrels, with the vague idea of wearing a dramatic squirrel fur ensemble to King Thranduil's being-begotten-day party. 

Úlairiel was a tall, slender Elf-maiden, whose hair streamed behind her like the great banner of the Woodland Realm (only not green).  Her eyes were like pearls fresh from the inner processes of the oyster.  She wore a long gown of cloudy silver, now marred poignantly with blood from a brace of squirrels slung over her shoulder.  She bore a bow taller than herself, inlaid with gold and strung with her own hair.  Her arrows were flighted with beautiful dodo feathers.

Singing, ambling and collecting squirrels, Úlairiel wandered a long way.  Suddenly she bumped into a tree and realized that it was getting dark.  She had left the path a long time ago, and had since covered distances that defied the laws of physics; now she faced the fact that she was lost.  Looking searchingly at the trees helped little; she found it hard to tell one tree from another even in daylight.

"Woe is me!" cried Úlairiel.  "Alas, for I shall perish in this wood, never to have known love!"  She collapsed tearfully under a tree.

Then a bird screeched somewhere in the forest, and, like a sign, Úlairiel saw a light through the trees.  Seizing her bow and squirrels, she rose and began to make her way towards the glimmer.  As she walked, more lights were revealed, and finally she rounded an enormous tree and saw a hill crowned with a great fortress.  Towers, flying buttresses, minarets; it was truly an impressive place.  The windows from which the lights shone were slits placed extremely high, and there seemed to be only one, small door with hefty iron bars across it, but to Úlairiel in her fraught state it was welcoming indeed.

She scrambled up the slope of the hill and hammered on the outer gate.  "Please permit me entrance," she called, "I am but an Elf-maiden, lost and alone!"

The gate flew open as though she had spoken a magic password.  "An Elf-maiden, lost and alone?" said a voice like razor blades being sharpened.  "My Lord bids you enter!"  And a hand in very spiky mail shot out of the gate, grabbed her neck and yanked her in.

"Ow!" cried Úlairiel, whose skin was delicate.  "Unhand me – " Then she fell silent as she beheld her captor.

She had never seen a male like him in all her two thousand and eighteen years.  The armour that covered his whole body was moulded into the shapes of formidable muscles.  Scored steel winked in the light of a guttering torch.  His cloak was black and fell in sweeping folds.  His hood enveloped his face, giving him a sexy highwayman look, but it was the face itself that made Úlairiel's heart flutter like a butterfly on a pin: a bottomless abyss in which she could drown.

"Oh…" she murmured.

She was affecting him too, she could tell; he stood stock still for a moment, the edges of his cowl trembling slightly.  In truth, never had such a sight been seen in the gloomy fortress as Úlairiel in all her beauty, standing with red and parted lips amid the shadows.

His gaze was too much for her, and she took a step backwards, fetching up against a corpse that was hanging on the wall.  She detached a set of fingers from her shoulder almost without noticing, staring at the figure who, she felt, must be her true love, the love she had foreseen in dreams and whose existence had been prophesised by one of the lost Istari (who had briefly emerged from the wilderness to bless her cradle).

"May I know the name of my lord?" she whispered.

"This ssservant...," he hissed, "lieutenant of Dol Guldur...of the Nazgûl...fair female."

"A Nazgûl?" Úlairiel gasped.  She had heard so many stories of the Nazgûl, but had never dreamed of meeting one.  He must be possessed of awesome powers, as well as being a king.  "But what is your name?"

"Name..."

"Yes.  I mean, I'm Úlairiel."

"This ssservant 'ssservant' to my Lord...'#5' among Nazgûl."

"#5," Úlairiel mused.  She had seldom heard such a beautiful name; it was like music, and it fitted him to perfection.

"Úlairiel...," he breathed close to her ear, making it tingle with cold and delight.

"#5..."

He was bending over her, and Úlairiel was lost in the infinity beneath his hood.  Black velvet swirled around her eyes.  Her hands tentatively touched his steel breastplate.

"I would stay with you," she murmured, after some minutes.

"Ride often...many dangersss...," he said.

"I can ride," she declared, "I'm strong and I'm not afraid.  Where you go, I will go."

"Go with...Nine?...Never done...before…Lord must be…asssked…"

"I will ask him if need be!" Úlairiel said passionately.  "No-one will part us!  And anyway, why shouldn't there be more than nine in your gang?  Another person could be wonderfully useful!  And I'm a great shot – see these?"

She gave #5 a squirrel in token of her love.  Then she marched into the fortress, fortuitously finding the stairs first time, and went up to find the master of Dol Guldur.