She really wishes she'd thought of it sooner
Pinkie happily bounced from one twisted spire of pentadimensional paintings to the next, while the sky below them swirled in a jagged maelstrom of sugar and letters. "Hey, Twilight!" she called to her friend, a couple centuries to her not-left. "How's it going?"
Twilight gave an annoyed grunt from her twelfth nostril, as forty-two percent of her eyes looked in Pinkie's cross-dimensional direction. "No better or worse than the last time you asked," the essence of Magic made flesh and unmade breathed into the fabric of reality around them. "And that was just ten minutes from now!"
The annoyance in Twilight's words shook the hypercube of honey-flavoured marshmallows Pinkie had lazily set her corporeal form on, and the avatar of Happiness had to wrench herself away from it and into a fold of time, as the structure exploded in a sidewards shower of meteoric glitter.
"I think you just created life on that planet!" the pink nebula of energy exclaimed, pointing a tentacle a universe and a star's lifetime behind them. "I wonder what kind of cakes they will come up with!" She began to fantasise, stars exploding in her mane as she let herself drift aimless in the storm of harmony around them.
Twilight shook her many heads. "Pinkie..." Shaking her heads again, in the opposite direction, to undo all the changes her previous motion had wrought upon realities unnumbered, the once and future mare extended one of her appendages across the infinite dimensions it existed in, over unending stretches of empty space and frozen time, to reach her notes and scribble indecipherable quantum lines of knowledge on them.
"Oh! Oh!" Pinkie fell back upwards, a grin on her face broader than the whole of creation. "I know what we can do. Let's play How Many Seconds in Eternity!" The chimes of her excitement harmonized through aeons uncounted, and every civilization ever to manifest a possibility of existence in the waving weave and time saw its greatest poets and artists sewn into their history where the sound crossed it, like lightning splitting the sky.
Twilight kept up her note-taking in every direction of time, as the pattern of her inscription grew ever more complex and vast with each subsequent split in probability, all of its realities collapsed onto one single set of multifaceted consequences. The result was a sight chaotic and meaningless to mortal eyes, but not to Twilight's all-encompassing atemporal vision.
"There's a universe large as a planet, denser than the densest of black holes," Pinkie began to recite, as she bounced around the curves of space and time. The ripples of her motions started life in as many solar systems as there ever were atoms in her old body through her entire life, yet also brought end to just as many through the relentless waves of all-consuming entropy.
"It's heavier than our universe as much as a star is heavier than a planet orbiting it, and time around it so slow it may as well be frozen," she continued. She seemed strangely cheerful, insofar as her hyperdimensional form let one discern. Insofar as her antilogical nature allowed such a being to be cheerful. It was more like a complex pattern of interwoven timelines and facets of potential realities manifest within her in that situation.
"Every time our universe collapses back in on itself to being its cycle of existence anew, a single atom is released from the hyperdense planet-sized universe," the timeless amalgam of metaphysical constructs and fundamental rules of creation that had once been and yet was and would be a pink pony went on. Her bouncing around had led her full circle around Twilight, back to the moment she'd started.
Pinkie stood still and firm, stark like a beacon across every reality. "And when the last atom has been released and the universe has disappeared, the first second of eternity will have passed," she declared, and the weight of her statement toppled galaxy-spanning empires and brought an end to beings so ancient they had witnessed the stars first give light and at last fade out.
Despite herself, Twilight experienced the closest thing the manifestation of Logic and Harmony itself beyond the boundaries of matter and energy could feel to a genuine smile. It was still closer to a living carbon-based creature's equivalent of one than what a hate-ridden soul could muster, a fact that both saddened and delighted her a great deal. "That sounds like a very long time, Pinkie."
The other shrugged, and forgetfulness was born. "So, how's it going there?" Out of the nothingness, she willed a crease into the fabric of existence, and twisted it on itself at angles beyond the limits of dimensions until it folded away and a bubble of non-existence came to be inside the outside the two manifested themselves in.
"No better or worse than the next time you'll ask." Twilight seemed to pause, looking everywhere but at the bubbling colourless void of rage and hate burning in times beyond time and spaces beyond space. Something had come from it, a lacerating cry from its innermost depths that echoed through the pillars of creation. But she wouldn't give it any acknowledgement.
Pinkie contemplated the waves that shook the roots of existence, absent-mindedly filling her bubble of nothing with swirling galaxies of sentient cotton candy. "Do you think we should address that at some point?" she asked, her tone hesitant. Then she let go of the question, and threw a single long look at the raven's nest beyond the hole.
Twilight meanwhile watched the question Pinkie had let go of fall down into the skies of chaotic energy around them, where it was torn apart and reduced to its basic components. And then an idea struck her, brighter than the light of every star in the universe combined as it shined from her heads like a halo. Quickly she retreated her appendage back from the distant aeons she had cast it through, her movements rippling through and reshaping multiverses.
"I should have thought of this sooner," the purple amalgam of cosmic anomalies chided herself, as she folded and twisted timelines together. Empty universes slithered from her form and sparks of nothing shot out around her as the whole of creation began to pivot and collapse onto her core, shifting in segmented shards that realigned themselves to exclude the centre of their motion.
Supernovae the size of atoms imploded as they tumbled upwards along the twisting ladder of times, and universes melded together as their matter broke down into boundless seas of harmonies and energy. The future fell like rain across the infinitely small fragments of the web that made up reality, as the consciousnesses of beings whose thought and will shaped the flow of causality seeped in through the cracks. Time burned and force shattered, and the spiralling weave of events bent over itself and filled its own gaps. Dimensions existing in the folds and pockets between each other were turned inside out, layers of reality superimposed over one another clashed and fused in a shower of sparks, souls that were never born danced through halls that never would be, and the mute cackling of undone conjectures resounded through the whole of everything.
And then Twilight Sparkle wasn't.
