Everything boiled down to the coming confrontation. Everypony she cared about was relying on her, whether they were aware of the situation or not. Without victory here, no living thing would survive the coming darkness; without the light of the sun, the world itself would die. It was not courage that drove her, but desperation, and hope. Hope that her life was not an attempt in futility. Desperation to accomplish what her mentor had left in her hooves. To make her teacher proud. Perhaps the others had their own reasons, but while their cause resonated with her own, their dreams were unknown to her, only their goal. The reclamation of the elements, the defeat of the Nightmare, and the return of the sun and the princess they loved to their rightful places.
Even as they journeyed to the old castle ruins, they could feel the temperature dropping. Not even a day and the planet was starting to cool. Not enough to cause problems yet, but for those attuned to the weather, like Rainbow Dash, it was like one of her feathers was bent at an odd angle; it drove her up the wall, and in this instance, there was nothing she could do to remedy the situation. So they journeyed on. Past the jaws of death. Over the raging waters that sought their hooves. Through the forest of terrors. Over the chasm and past the temptations of fame and power. Finally, they made it. They found the one weakness of their enemy, and the thing that would bring balance back to the for- I mean, Equestria.
However, something was wrong. They wouldn't activate. The legends said that a spark would ignite the power of the final element, so why, no matter how much power the young mage poured into these blasted rocks, did they not react? What was she missing? What if- no, she'd come too far, she wouldn't fail her friends, her family, her princess. Not when she was this close.
Then she made her move. The nightmare was no longer content to sit idly by while the mage struggled to unravel the mysteries of the universe. In the flash of an eye, she was elsewhere, separated from her fellows, alone against a twisted goddess. A being she could never hope to match. But Twilight knew she didn't have to match the nightmare. All that Twilight needed was on the floor behind the monster. Lowering her head and beginning what appeared a suicidal charge, she faked the monster out, making a final desperate lunge for the elements, a final desperate grasp for the spark that she'd been unable to find.
But she failed. The monster shattered the Elements, and with them the hope she held. Until she heard them. The others, rushing to her aid, even as doom drew near. Truly, she would never again meet such loyal, generous, honest.... wait. Was that it? It was! She felt it, a different spark. Not a literal, but figurative one. The same issue with so many legends, and if they should be interpreted literally or figuratively! And with that spark came renewed hope. She identified each bearer, the elements alighting upon each mare in turn, followed by her own, as the truth of the situation became apparent. With this new hope, this new power, a new day would finally dawn, and the darkness before them cast down forever more. The mage focused the energy about her with her purpose: End the nightmare. End the eternal night. And as she wished it, the energy responded. The rainbow of light was beautiful, and the Nightmare caught flat-hooved. As her consciousness slipped away, her only thoughts were of victory. She'd made her princess proud.
<-()->
Twilight cracked an eye open. A moan from behind here told her the others were just coming around as well. She recognized the symptoms they were suffering from. Complete magical exhaustion. When the body has no more left to give, it shuts down, leaving the caster to regenerate their mana pools to sufficient levels before the caster can become active again. But that didn't matter, they had- wait, why was it still night? That was impossible, the elements had defeated the nightmare. There should be nothing holding back the sun anymore!
Stumbling to her hooves, Twilight made her way as quickly as possible in her current condition to the armor of the nightmare, seeking answers. What she found was not only confusing, but terrifying as well. Lying amidst the smoldering armor was a strange creature she had only read about in bestiaries and books of myth in the Canterlot library. A black insectoid creature known to the laypony as a changeling.
But how? How could a changeling have impersonated the Nightmare so perfectly? Such creatures were not capable of that kind of magic. The cloud, the illusions, sealing the princess away. Not to mention no living creature had seen the nightmare for a millennium. For a solid minute, the genius could only sit in silence as her mind desperately tried to piece together a puzzle for which she did not have all the pieces. Twilights mind was a supercomputer, make no mistake. Any problem given to her, any task assigned was completed with the full focus of her mental faculties. But in this instance, it all failed her.
The wheel kept spinning, but the hamster was nowhere to be found.
<-()->
"BWAHAHAHAHA! She actually thought I would stick around when she got her hooves on the one thing on this green planet that could stop me? It's so naïve I don't know whether to pity her or have her executed!"
Beside the hysterical ruler of the night, a large chitinous creature, nearly the same size as the nightmare, giggled along at the images displayed in the viewing spell suspended in the center of the Canterlot Throne room.
"Indeed, I told you this would be worth it. The looks on their faces when they realized their quest was for naught was wonderful! My only regret is not being there to taste their despair. I'd get indigestion afterwards, but it would be worth every pained moment!" The Queen tittered.
The nightmare gave a toothy grin at her fellow conspirator. "Agreed, the looks of hopelessness are wonderful. I'm glad I remembered the spell for making memory gems. This one is going on my dresser. Would you like a copy?" Her mood was adamantine as she turned to the Queen beside her. Perhaps the bug wasn't so bad after all?
Chrysalis herself was allowing herself to bask in her victory, not just metaphorically, for allying herself with such a powerful figure so early in her reign, but factually, from the comraderie flowing from her fellow in harms. Truly, nothing brought together evil despots quite like watching the populace suffer. Now if she could just convince the idiot that she was well on her way to wiping out all life on the planet, everything would be awesome. 'hm-hm-hm-hm-hm-hmmmm....'
Nightmare's ear twitched as a strange sound reached her, originating from the changeling. "Did you say something?"
"Huh? Oh, no, just a tune I heard somewhere..."