Teros

It's cold.  Freezing, even.  My eyes flutter open and I groan, feeling the icy embrace of the cave's floor beneath me.  I can feel my skull throbbing as I cast a simple light spell across the pitch-black cavern.  As I blink to clear the murky edges of unconsciousness from my vision, the entirety of this nightmarish place comes into view.

I am in a tiny, claustrophobic chamber.  The only light source is attached firmly to my head, and whenever I move the slightest bit, shadows dance tauntingly from behind the jagged crystalline shards that stab their way out of the floor.  The air is dank, and the only sound heard is the occasional dripping of water and the echoes of my own shallow, panicked breaths.

"Shining?!"  I call out desperately for my fiance.  The only answer is my own voice, distant and muted, bouncing off the walls of this awful dungeon and taunting me with my own isolation.

"Shining Armor!  P-Please, where are you?!"

"Mmmm...  Hmmhmmmmm...  Nopony can hear you, princess."

The last word is dragged out, stretched thin like a wet tissue.  That voice.  I know that voice.

"Y-You!  Where are you, I-I know you're down here!"

"Oh, Mi Amore Cadenza, you don't know anything about me."

Her face appears behind—or maybe within—the smooth rock wall before me.  I feel my muscles tense up.  I grit my teeth, and with a scream, fire a condensed beam of magic into her smug, chitin-encrusted face.

My attack is met with a chorus of hideous laughs and my own spell rebounding wildly around the chamber.  I dive to the floor, covering my head with my hooves as the reflective walls around me bounce the stream of deadly mana across the room.  I see it flying towards me, and on instinct, a blue bubble coalesces around my body, absorbing my own lethal blow.

"Look at you, Cadenza.  Cowering like a rodent from your own power.  Honestly, I'm doing your country a service by leaving you to rot in these caves."  The voice comes from behind me, and I spin around in a haste, my horn glowing with violent energy.  My eyes flick around the room, but I find nothing but soulless walls of crystals.

"Oh please, Princess.  Do try to maintain whatever dignity I've allowed you to keep," she says, her voice echoing within itself as if her very speech was coated in deceit.  She breaks into cackling laughter as I spin around again, flaring my wings.  "Heh heh heh...  Mmmm.  Yes, it will make this all much more painful for you, and far more amusing for me."

"What do you want from me?!" I scream.

"I want what you've so selfishly hoarded," she snaps.  "I want what all things living beyond Equestria's borders want."

My head is spinning as I turn around once more, my horn searching desperately for a target.  "I don't understand!  I don't have whatever you're looking for, so let me go!"

"Hmmmhmmmhmmmmmm...  Cadenza, you silly girl.  One of the greatest powers in this world is yours to manipulate like clay, and yet you refuse to act."  I look up, and find her gaze—my gaze—staring back.  "And so, I will take it from you."

The white-hot energy leaves my horn, dimming the room.  I stare at this menacing copy of myself, and fall to my knees.

"What...  Wh-What are you...?"

She giggles in my voice.  "I am the beginning of your end, my dear."

I don't reply.  I can't think of a reply.  What was once some hideous beast of an equine now wears my skin, taunts me with my own voice, and stares me down with my own eyes.   Auntie Celestia never prepared me for anything like this.  I've never even heard of anything like this.

I curl into a ball on the cold, hard floor, squeezing my eyes shut.  Her voice echoes from all directions at once, like a deadly bolt of mana streaking across the room.  "I will take from you everything that you love, Cadenza.  I will bring your kingdom to its knees.  I will destroy everything and everypony you hold dear."  I squint my eyes open just in time to see my own lips delighting in every syllable of what she says next.  "I will drain your precious groom-to-be until he is nothing but a dried husk of a stallion."

Tears build up behind my eyes, forcing them shut again.  I lie there, shivering, as the room becomes black as night.  Any energy I had devoted to my light spell is gone, and as all my hopes and dreams and desires for the future drain out of me, her voice—her horrible, echoing voice—tells me one more thing.

"And then I will kill you."

I can't breathe anymore.  I can't think anymore.  As her cackling fades into hollow echoes against the chamber's walls, I roll limply to my side and lie like a discarded doll on the cavern's floor.

"Sh-Shining...  P-Please..." I whimper, but there is no reply.  There is nothing here but myself and the darkness, nothing but the empty sound of my own pitiful gasps.

"Auntie Celestia...  L-Luna...  Tw-Twilight..."

My cries are met with only the echoes of my cries.  The dull chorus of pleading desperation is my only company as I close my eyes to the blackness and break down into sobs.