Twilight throws herself into the miasma surrounding Cadance's heart and finally fights her way through to Cadance's consciousness, with the two of them combining their power to purge the dark magic altogether. The whole circle of family and friends enjoys a reunion, while the Grevyians and their hirelings set a record for steepest Villain Decay as the ponies retake the streets of Canterlot.
Lord Mathos vows that if he cannot take Equestria, nopony else will survive the night either, sending word to Jugurtha to execute the bound Celestia. Turns out he had also kept scrying on Dawn and decided that unleashing the buried balrog is perfect for one final "buck you". Swaggering down into the mines, and thinking one last time of his own family, he calls (and potions) the fire demon to arise before becoming the first victim of its blaze.
Dawn somehow realizes that Twilight is back in commission and teleports up to Celestia to cut her off at the pass, shocked to find the zebra soldiers guarding the sun princess. Jugurtha gives the kill order on both of them but Dawn manages to fight him off after flash-banging the other soldiers. And, after so many years and so much plotting, Dawn turns to her old mentor to receive what's coming to her:
She turned to face Princess Celestia, a beaming smile upon her face ─ and was immediately hit with a full body bind that wrapped her up in golden ropes that would not break.
"You come here," Princess Celestia seethed, her voice quivering with anger. "You dare to speak to me thus, to show your face to me after what you have done?"
"Princess Celestia," Dawn said, squirming as the magic held her in the air. "It's me, it's Breaking Dawn." This is a misunderstanding. She thinks I'm somepony else, or she's forgotten who I am and thinks me impertinent, that's all this is.
"I know who you are Dawn," Celestia shouted. "I know what you have done. I know everything. How you poisoned my niece Cadance, how you have hunted, wounded and betrayed Twilight Sparkle. Where is she? What have you done to my student."
Her she calls 'my student', me she does not seem to remember at all. "I did nothing. I left her out of the city, trapped but safe. I meant no harm to her as I meant no lasting harm to Princess Cadance. I did only what you asked of me."
"I asked," Celestia said in tones of utter incredulity.
"When you cast me out of your school you said that you and I might meet again if I could prove myself worthy," Dawn said, smiling. "I figured out what you meant. It was a test, your last test to see if I really was ready to fulfil my destiny. I had to triumph over absolute adversity. You wanted to see if I really had what it took to rise from nothing to the very pinnacle of success. It took me a while but I finally realised it. And I did it Princess! I had nothing, absolutely nothing at all. But with hard work and a little help from my friends I won everything. I defeated Twilight Sparkle, I got into court. I've gotten here, and now I'm with you. And that means I pass, and things can go back to the way they were...right?" Hold me close the way you used too.
Celestia's eyes were wide with shock. Slowly she lowered Dawn, still bound by magic, to the floor. The Princess said, "Oh Dawn, I am so sorry. I did not do right by you."
Breaking Dawn blinked, "Princess Celestia, I don't understand." My dream, my dream showed that I would fulfil my destiny, that I would be adored by all ponies. How can this be happening?
"Breaking Dawn, when I said those things I never," Celestia shook her head, "I never intended for you do what you have done. I meant for you to find your own path in life, become successful in a field of your choice."
"A field of my choice?" Dawn repeated. "A field of my choice? Something not as glamorous as saving Equestria, obviously."
"Every endeavour is equally meaningful so long as you put your heart into it," Celestia said.
"No it isn't!" Dawn yelled. "That's just what ponies say to make themselves feel better. 'Oh sure, I work in a life insurance office making seven bits an hour but my work is every bit as important as raising the sun!' You told me that I would be more than that, that I was better than that. There were promises made between you and me, Princess."
"I was mistaken," Celestia whispered.
"Mistaken," Dawn's eyes were filling with tears now, tears of anger and sorrow intermingled. She wanted to lash out with magic and strike at Celestia. She wanted to embrace her as a daughter embracing a mother. She wanted to cry, she wanted to scream, she wanted to fight, she wanted to collapse in a heap. "I got fired from every job I ever had because you filled my head with talk about my greatness, my destiny. You made me think I was so awesome I was too good for anywhere that would employ me, too good to take orders from anypony. And now you tell me you made a mistake and it was all a bunch of horse manure."
Celestia was weeping too, crystal tears falling down her glowing white cheek, "I cannot apologise enough for what I did to you, Breaking Dawn. It was wrong of me to put so much weight upon a filly so young. I used you, and when I could not use you how I wanted I set you aside with undue haste. All your failures as a student may be laid at my feet as your teacher."
"No, no Princess don't blame yourself," Dawn said. "I hate to see you sad, don't cry. But, but why couldn't you use me? I wouldn't have cared what it was you asked me to do. I love you, I am your most loyal servant, the most faithful pony in all of Equestria. I would have died for you had you commanded it. I told you that I would do anything to stay by your side, so why couldn't you use me."
"Because you are not the pony that I thought you were."
"But Twilight Sparkle, she is," Dawn demanded. "What makes her so much better than I am? I have as many friends as she does. I am as charismatic as she is, more I think. I understand friendship, harmony, courage, generosity as well as she does. She's a little more powerful than I am, but that shouldn't matter should it? What makes us different, and her better."
Celestia bowed her head, closing her eyes, "I learned from the mistakes I made with you. Twilight was ignorant of her destiny, lived her life not knowing the plans I had for her. And thus she was not corrupted by her position, by the power she would wield. She never grew arrogant, as you did."
"That's it?" Dawn shouted. "I am condemned for a fault not my own."
"You are condemned entirely for faults your own, Dawn," Celestia said, her voice growing cold and stern. "As a student you were vain, lazy, disrespectful to your professors and disdainful of your fellow students. And now, as a grown mare, you have grown vicious and cruel. What you did to Cadance, whatever your intentions to reverse it, whatever your motives, your actions these past weeks have been absolutely unforgiveable.
"You have disappointed me in ways I never believed possible Dawn. As much as I regret my failure to better help the filly that you were, the mare that filly has grown up to become disgusts me."
"No," Dawn sobbed, sobs that were childlike in their broken-heartedness. "No, this isn't how it's supposed to be. This isn't what I was promised. I had a dream, a dream. I'd save you, then you'd embrace me like the old days, and make me a princess and..." Dawn's tears fell heavily upon the crimson carpet. "All I wanted was to be great, to shine, to be loved by you. Was that so terrible a dream to chase?"
"Only when you sought to rise at the expense of others," Celestia said.
Before Celestia can finish passing judgement, the balrog makes itself known, and, despite Celestia's pleas for Dawn to surrender the Elements for Twilight and friends' use, Dawn bursts out of there for one last shot at glory, teleporting back to her friends. The gang dons the Elements and Dawn leads them up to face the demon before summoning her magic...
...and nothing happens.
At least, at first.
Turns out getting turned into a raging she-demon is a karmic retribution on the Element of Magic's part.
So you are the pony who sought to gain the powers of Harmony? Arrogant fool, did you truly think yourself worthy?
Yes, Dawn did not think the answer so much as it was dragged from her mind, torn from out amongst the pain and the confusion and the constant yelling. Dimly, she could hear her friends crying out, asking what was happening to her. But all she really hear was the voice in her head.
Then you are as stupid as you are over-proud. One such as you, who creeps and crawls and strikes from the shadows, will never be fit to embody Harmony.
But, you called out to me, I heard you singing...
A siren song, to lure those who would seek me out of the desire for power or fame. My true bearer hears nothing from me, for I am nothing to her but a means to protect that which is truly precious.
Dawn started yelling even louder as she felt her skin being torn apart, demonic wings erupting from her back, claws sprouting from her hooves. The pain was like a zebra crucifixion.
What's happening to me?
You are being punished for your hubris. You will wear your soul upon the outside now.
No, please. I was supposed to be great, known throughout the land.
You will be. As a cautionary tale.
"Get it off her, get it off!" Candy's yelling was muffled as though by water.
Dawn could dimly feel Razor's hooves upon her head, even through the distance and distortion she could hear the pain in Razor's voice, "It won't come, it's like its fused to her head or something."
She felt Cherry's touch but dimly as the pegasus hugged, "Please Dawny, please stop. Come back to us. You don't have to hurt. You don't have to suffer alone because we're all here."
Is this hurting them?
Only when they touch you.
Do whatever you like to me but you can't hurt them, they don't deserve it.
Then make them let go.
"Let go," Dawn croaked through her agony. "Get away."
"No can do sunshine," Razor growled through gritted teeth as lightning lashed her hooves and forelegs. "I'm coming away with this crown or not at all."
"You can't leave us Dawny, we need you," Laurel pleaded. "You make us more than what we are, you always did."
"We already lost you once, we can't lose you again," Candy said.
"Please Dawn, if our friendship means anything like as much to you as it does to us," Hardy said.
Your friends are worthier than you yourself. Be thankful for them.
The pain lessened. Dawn found she could stop screaming as she felt her body returning to its normal pony state. The lightning all around her died down and vanished. Razor, hauling upon the Magic Crown, flew backwards, bounced along the ground and let the crown slip from her scorched hooves to fly away into the night.
Breaking Dawn collapsed in a heap on the ground, crying.
They were right all along. Celestia, Twilight Sparkle, all of them. It never was my destiny at all. They were right, and I was so wrong.
"What do we do now?" Hardy asked. "Dawn, what happens next?"
"I don't know," Dawn confessed for the first time since her mad scheme began. "I've no idea where to go from here."
