Celestia sighed when the two changelings were set down before her. She stood up and marched forward, but to the queen's surprise and horror, she stood before the youngest of the two. She closed her eyes, and lowered her head to face the young changeling prince. She said, "I know that you're scared, and to that you have every right. I am something to remember, little one, but you needn't worry."
Chrysalis's eyes clamped shut as she recalled all the princess had done to her children, assuming that her last son would meet a similar fate. She glanced at her son's eyes as the princess held his gaze. She willed her jaws to open, with all of her willpower, she fought against the halter's spell.
The prince focused his attention on the leftmost edge of his vision, towards his mother, just in time to see her halter snapping, ripping apart under her will. He watched as a dozen guards pinned down the queen, holding spears at her head and pinning her hooves against the ground with their own, and summoning shackles with their magic.
Princess Celestia stood up, and looked at the queen, who wasn't even resisting the guards as they restrained her. She felt pity for the queen, who had traveled so far, and fought so hard to find her. She opened her mouth to speak, but froze when the smaller changeling fell forward, and his horn connected with hers.
In that instant, everything fell impossibly far from Celestia's control. A flood of raw, untamed magic flowed from her body, through her horn, and into that of the young changeling. She collapsed, drained of her power, and bounced off the ground a few times, her crown landing a few centimeters away from her nose.
The guards assumed that this was some trick of the queen, and that she had killed the princess. Perhaps out of bravado, perhaps of idiocy, perhaps of good intentions but misplaced actions, a spear was driven through the queen's skull, and she lay there for a moment, bleeding, before her eyes rolled closed.
The prince's halter, unable to handle such a flood of magic from its captive, burst into shimmering dust. The young changeling stood, and opened his eyes, showing the guards two orbs of endless, merciless fire. His horn erupted into an earthen green flame, which spread across the surface of his body.
He should have been unable to control so much magic, so much power, but his father had left him that capacity. And this changeling possessed, in that moment, more power than any other living creature on the planet. Not Celestia, from whom his new strength was taken, could have stopped him from destroying Canterlot.
Discord, who had, in all likelihood, the ability to cripple such power, could have done nothing in the face of so much rage. This timid changeling, only half alicorn by blood, was the most powerful being in existence.
Celestia frantically glanced at the window, dismayed to find that the sun was not up. She could not have moved the sun at that moment, nor could she have turned back time to undo this mistake. She was at this changeling's mercy, and, by the fire in his eyes, he was not too keen to provide her anything.
She hoped her death would be quick.
The guards made such haste, practically vanishing altogether, as the new superpower before them marched. He stopped at his mother's dead body, and when he blinked, the fire, the rage, the hatred for whom had done this, evaporated from his face. His toxic green eyes welled up with tears, and he wept, for he could not know what power he possessed, nor what he could do for his mother, likely the only person who could help him manage this magic.
He stood, then knelt, nudging his mother's shoulder with his nose, urging her in his native tongue, "Please... come back..." He traced his mother's shape with his gaze, then that of the spear, which was still buried in her head. He whimpered faintly, and spoke in English, which he'd stolen from absorbing Celestia's magic. "I... I will do what I can... for my home..."
He sniffled, and cared not for whom may have been watching. He bawled, constantly slipping between changeling and pony words, "G-go see father... Tell him that I-" He coughed as the stench of sweet ichor flooding his nose drowned out the world he'd already forgotten. "I miss him, and you."
He closed his eyes, lit his horn with a green glow, a bit too brightly to pass as normal, and his mother's horn glowed in turn. He knew that she wanted him to have it if she ever died, that it was her wish that he take it with him, carry a piece of her. He knew that she wasn't coming back, but wished that he didn't have to confront it every day for the rest of his life.
Celestia's eyes widened as the queen's horn was snapped off, leaving nothing of it on her head. An instant later, the rest of Queen Chrysalis's body disintegrated, and blew away in the wind, which had been let in by the suddenly open windows. She didn't know how to feel about this.
On the one hoof, one of Equestria's greatest enemies was dead, and her only heir was hundreds of kilometers away from his kingdom, which had just evicted him, so they wouldn't have let him back in anyway. She didn't have to worry about more changelings being born. This was good.
On the other hoof, that heir was her nephew, and had just stolen nearly all of her magic. He was unstable, wrought with grief, and suddenly more powerful than she was. Her nephew, who probably didn't know that he was her nephew, had just lost his mother, who hadn't even resisted the guards after freeing herself. She was surely about to die.
On the other other hoof, she couldn't undo any of what had just happened, move the sun, or explain to him why he shouldn't kill her. He didn't know how to reverse time, nor did he even realize how much he needed her advice in order to manage his newfound powers. Reason might dictate assisting the poor child.
But she couldn't do anything, as the changeling prince charged towards the window. He slipped between the panes of glass, and dove straight down. This alarmed Celestia, for if he died while carrying most of her magic, it would all die with him, disperse back into the world, and she would not be able to even consider undoing all of this for a very, very long time.
The princess of Equestria lay there, purple eyes glazed over, mane solid, lying flat against the ground, crown standing on the floor. She remained there for a few hours, until Princess Luna came flying down the hallway, shouting, "'Tia, why is the sun still down? I've already lowered the moon a-" She landed, eyes wide, watching her sister breathe. "'Tia!"