"Harmony is not won, it isn't earned either. You can't spend your life trying to make peace or finding it. Harmony, peace, and serenity are lost every second of every day. Once you lose it, you can't get it back... But, you can nurture what's left and love it until it is ready to grow. And, when it does start to grow, maybe it'll be in a time and place that's ready for it. And if not... Well... At least you tried." - Princess Celestia.
Heaving cough after cough, Nightmare Moon could not force out another scream as the flames of Solaris kept a firm grip against her throat while pinning her to the wall. Though the haze of heat put everything at a waver for Nightmare Moon, she could still see her sister rising from her bed and stalking over to her pinned form. "You dare raise your horn to me?" Solaris tightened her flames around her sister's throat, choking her windpipe out with not only the blistering pain but the thick smoke, "I have raised you better than this, Nightmare Moon... I have given you everything and this is how you treat my actions?"
The dark mare managed a few more dry crackles of breath between the living flames continuing to wring her neck out and scorching against her chest. She had hesitated for just a moment... A moment of doubt that she had hoped would not rise at the deciding moment but had. In that one moment, everything fell to pieces. Nightmare Moon saw from over her sister, in the glaze of the window, the sun had begun to rise once more and to bring the dawn. The dawn of Solaris' power... The dawning of her unimpeded reign. "Nightmare Moon, I will grant you but one last moment to speak your will only for the matter you are my blood. That alone is all I will grant you as a chance to save yourself or I will not hesitate to finish you here."
"L..." Nightmare Moon looked down to her sister with glassy, dead eyes, struggling for a breath as a dark spark started to glow through her horn.
"What are you saying?" By whatever force, Solaris' flames dimmed slightly, decreasing the tension against Nightmare Moon's throat.
"M...My... My last will..." Celestia... I wanted nothing more than to bring you home. However... "Dear sister... My last will..." Suddenly, the entirety of Solaris' chamber was drained of light as Solaris' flames were extinguished and the world outside faded to a blood-red darkness. Nightmare Moon fell to the floor, her lungs clearing and her eyes glowing to a blinding white, becoming the center of Solaris' attention along with the erratic celestial hair of her sister suddenly growing calmed and taking to a central form, sparkling through the darkness. Solaris staggered back towards the blood-red world blocked from them by the windows, her own smoldering eyes stunned by the sight of her sister looking at her. "My last will... Is to free this world from you!"
Solaris hadn't the reaction time she presented before when she had caught her sister; unable to protect herself as a bolt of blue-black energy struck her to the chest and flung her out one of the windows of her chamber. The look of confusion and fear was still across Solaris' face as shards of glass and broken window splinters surrounded her in the air as she was sent into the air. To Solaris, time seemed to slow down; frozen in the air not by her own power or anything else; as if everything was just being pieced together for her. "Why...? Why can't I--" Her own thought was answered when she saw the sun or lack-there-of. In the time of her gripping and choking her sister, she did not notice as the moon had been lowered to conceal the sun behind it. The centers of all her power... Her armor? Given to others for safe keeping. Her guards? Put at ease. The sun? Blocked out by the moon.
She... Was defenseless. That was when time finally caught up to her and she sent for her wings to flick out from her sides, but all for nothing as the flames that filled her wings would not ignite. Her sight fell to the kingdom below, where she was now falling towards. All she could think about was this... betrayal. At that same moment, her plummet was ended as she was consumed by an unseen force of magic. From behind and above her, she could hear the flaps of large wings, along with the feeling of hateful eyes. "...So this is how you end me? With betrayal?"
"Betrayal? You view this as betrayal?" Solaris was made to spin to face her sister and the reality of the event. Before her, framed by a blood-red sky was no longer Nightmare Moon. Before her was a purified being clad in ornate and magnificent armor; shielded behind her by a pair of radiant wings that held the night sky within each plume. "This is not betrayal, Solaris. This is what you have brought pain for! This is what you have destroyed for! This is what you brought nightmares for! This. Is. Retribution!"
What defines us as who we are is every action that happens to us. Not the action itself, but... How we react to it. For better, or for worse, maybe being happy in a case could be bad. Perhaps becoming angry when we shouldn't could be good. In the end of the line, we can't know what each of these actions could have brought us. But, if you ask me...
All of Caballussia looked to the sky, waking their young, elderly, and resting to see what all had given dream to. Blood drained out from the canvas of the sky, bringing to it an almost harsh sparkle of blue to the darkened world. All ponies watched as the moon moved below the horizon while the glaring sun lifted high into the supposed noon sky. Several shooting stars shot through the blue sky in every which direction as a dark form took center in the vision of the sun. "Citizens of... Of Equestria... Solaris... Is. Banished!"
"Equestria" screamed with joy and wept of all the horrors past. For now, Queen Luna had freed them all.
...I think our world has gone pretty well. - Celestia