Always
Twilight was running. She didn't know what she was running to, or why she was running, but she was running, and she embraced it. Her metal legs bounded off the ethereal grass as she ran, kicking up tufts of dirt and plant. The edge of the platform came up, and with a powerful kick she leaped off the edge, coming to a running landing on the next. She kept up her speed, the whirring of gears and shining of metal in her body comforting to her robotic senses.
A white crystal loomed before her. Charging her horn, she formed a rainbow-coloured cone around her head, and shattered the star-shaped crystal into a million shining fragments as she came out over the abyss. She pushed off of the air, leaping to the next platform. She kept running, pushing harder and harder as the cloudscape behind her slowly drifted past. A trail, coloured like the shades of her mane, extended out from behind her, following the shape of her perilous journey over the leaps, chasms, and islands of the skies.
As she ran, she became faintly aware of a music filling her ears, repeatedly saying something about always and harmony. She ignored it, as something else quickly caught her attention. A gleaming silver dolphin jumped in and out of the slowly drifting pink clouds below, chittering as it dipped below the drifting masses only to reappear a second later. Twilight soon realized she could spare no attention, however, and darted forward.
Her mechanical muscles pushed to their extremes as she ran, jumped, and smashed her way across the floating islandscape. The world beside her became a blur as she increased in speed. Soon, she felt herself being freed from her earthly shackles. She felt her metallic body slowly rise, rise as if levitating off ground, and began gliding across the ethereal landscape, pushing harder and harder. A pair of dolphins began to swim through the air alongside her; but she paid them no heed as she pushed harder and harder. She felt the wires and gears of her robotic body cry out against her pushing, but she paid them no heed, darting forwards along her path.
She heard the song again; louder this time, and more forceful. Instead of tuning it out, she allowed it to flow through her, carrying her faster across the landscape. It no longer mattered what passed by her, what she dashed through, what she leapt across. All that mattered was getting to the end of her journey, no matter how far off it may be, no matter how many tiny floating islands she'd have to leap across and how many stars she'd have to run through. She ran through grass, through crystal, through air, focused on her eventual goal.
The dolphins began to follow her on both sides once again, but this time there were hundreds of them, and they were no longer friendly. Silver bodies began to pile up behind her, the residue of failed attempts to tip her off balance into the abyss below. She simply pushed harder, their gleaming silver growing nearer. Each body that landed closer to her gave her the power to put more distance between her and them, until they could no longer catch up to her.
She ran on for hours, being carried by the repeating cries of harmony, feeling them coursing through her soul, empowering her. The sun began to set, tinting the otherworldly islands an orangish colour, but she paid it no heed. She just ran, ran freer than she had in years. She knew she had to get to the exit; that it was the only to save herself and those she cared about. She dashed across the ethereal islands, across the candy-coloured clouds, under the slowly appearing stars, as she made her way to the massive steel spires. A stone wall appeared in front of her, too strong for her to dash through; but she felt no worry. The song curved her sharply upwards, allowing her to run across the wall to where her friends and her real body awaited her. She crested the hundred-meter-high stone monolith, dashing down the other side with the sheer force of gravity, harmony, and her legs powering her. Her chrome-plated hooves dug furrows into the wall as she darted down its face, inching nearer to her eventual salvation and her goal.
A yellow glow emanated from the spire that held her exit; ignoring the collapse of the wall behind her and the subsequent crumbling of the platform, she rushed forward. The cracks of the crumbling platform rushed after her, threatening each second to engulf her. She continued to race against the destruction, but the harmony had pumped as much speed into her as it could; eventually, the crumbling of the platform caught up with her, taking out the ground below her legs. She did not fall, however; while the harmony could not push her any faster, it could create a rainbow-coloured bridge underneath her for her to dash the final few yards.
She finally came to the spire, and burst through the window into her own world. Her body instantly morphed from the robotic beast she had once been back into its original form; however, the world around her was still in ruin. Pink clouds were alternating between raining drops of chocolate and deadly spikes, and the floor had quite literally become lava. However, the harmony was overflowing from the other world into her own. The song penetrated the air, spreading tendrils of harmony around all that was corrupted. The pink clouds became white; their rain turned from a deadly rain to refreshing water. The lava landscape returned to grass, and the utterly destroyed town returned to its original harmonious form. In the central square, the Monarch of Chaos, Discord, watched in horror as the rainbow-colored tendrils reversed all the work he had done. Seven shapes materialized from the ground in front of him as the tendrils came up to the base of his throne before stopping, followed by a purple unicorn.
Followed by the newly-raised princesses and her friends, Twilight wasted no time in donning her element, levitated over to her by Celestia. With the dual force of two worlds' harmony, a massive rainbow emanated from the Elements, crushing the chaos inside Discord into a pulp and leaving only an emaciated, horrified draconequus. But the wave of harmony did not stop there; where the force of one harmony could reach, the dual power broke through; a tidal wave of rainbow emanated from Ponyville, slowly spreading out over the entire world. Clouds of chaos all over the planet dissipated as the wave of pure harmony blasted through them, rendering them into nothingness. Within twenty minutes, the entire planet had been cleansed of chaos, and Discord's century-long reign was over at last.