Prompt: 100 Heartbeats

One hundred heartbeats. For some, it’s an eternity. For others, merely a minute or two.

Strange how time can twist itself so, thought Celestia, even as she dodged another volley of ravenous midnight fire. All a matter of context, I suppose. The next volley came, clipping her on the wing this time, and she cried out in more than physical pain. The being across the room from her gave a horrible, chilling laugh, and she barely managed to struggle to her hooves again before black, flickering tendrils sped towards her. She focused, leaping up and blasting the evil, fiery tongues away with a burst of brilliant golden magic. It wasn’t enough to dispel them completely, however, and she soon found herself entangled in the same deadly dance she had been performing since the moon had set.

Eighty heartbeats.

There was another cold laugh from the dark, flickering, alicorn-shaped form at the room’s edge, and Celestia had to repress a frustrated scream. Please, Sister, she thought desperately, ducking to avoid a gigantic spectral axe that had materialized above her head, if any fragment of you is still there-

“Fool.”

Sixty heartbeats.

The dark being’s voice echoed across the half-destroyed chamber, causing Celestia to pause for a moment. She nearly paid for it with her life as a pillar of black fire erupted out of the ground beside her, singing her coat and feathers. “Your so-called sister is no more than a shell for a power far greater than her feeble offering,” the dark alicorn said, spinning and lashing out with a magical whip. “A worthy, vessel, I admit, but no more than that.” It gave a mocking smile. “I may return her to you when she has exhausted her use. The Royal Statue Garden has been looking rather bare lately, hmm?”

Forty heartbeats.

Celestia had to choke back a sob as she parried the whip’s lash with a shining golden lance of her own. This horrible perversion of the soul she had known for millennia, this creature of malice and spite, this... this... thing, had replaced the elegant, intelligent, and dignified mare she had once shared long, wandering conversations over steaming cups of tea. How long ago that seems, she thought bitterly, shoving her foe back with a burst of golden light and blocking the retaliatory fireball. And soon, it will feel longer still.

Twenty heartbeats.

She could feel it now, the gentle, soothing hum of her six greatest achievements as they were drawn to her across the eddies of time and space. They calmed her, lightening her hooves and sharpening her senses, and she gave a sad, resigned, smile. Soon, sister, you will be nothing but an old mare’s tale, forgotten by all but the most devoted of scholars and the one soul who remembers you as you were. The hum increased, and she leapt high into the middle of the chamber as the air around her began to warp and shine.

Twelve heartbeats.

“What is...” The dark being paused, its flickering maw parting in an expression of utter terror. “NO! I AM THE DARKNESS THAT SHALL CONSUME THE COSMOS! I WILL NOT BE ENSLAVED! I WILL NOT BE DEFEATED! I AM NOX!” It began to back away as six glowing, gold-encased gemstones materialised around Celestia and began to hum with power.

Six heartbeats.

“Sister, please!” begged Celestia. “You’re stronger than this, I know you are! Please, abandon this and-”

“SILENCE! YOUR SISTER IS NO MORE! ALL THAT REMAINS IS THE ETERNAL NIGHT THAT SHALL-”

Two heartbeats.

The Elements glowed, spinning faster and faster as the corona of light around Celestia became brighter and brighter. The Nightmare howled in pain as the light reached it, clawing back at the radiance as though it was a physical force.

One.

“I AM NOT DONE WITH YOU, HEIRESS OF THE SUN! I WILL RISE AGAIN, AND ON THAT NIGHT, YOU SHALL REGRET ALL THAT-” The rest of the speech turned into a scream as the light consumed the dark alicorn fully, enveloping it in a shining cocoon that began to rise towards the ceiling above. It lifted through the castle’s crumbling roof, continuing up through the sky until it was little more than a glowing speck like so many of the stars that littered the night sky.

I’m sorry, sister. I’m so sorry.

Celestia stared up at the stars, Elements now lying dun and discarded at her hooves, and softly began to cry.