This chapter was written by Spectral.
"Back to the scene of the crime then, huh Meph?"
Mephistofilly froze at that, before slowly turning towards Discord. Her eyes spoke only of malice, and she gave him a strained smile.
"On second thought..." Meph turned to Celestia. "You will take that path," she said as a matter-of-fact, raising her hoof and pointing towards the wall. As she continued to speak, the stone came to life and formed a narrow tunnel leading upwards. "The tunnel emerges at the foot of a nearby mountain. Fly northeast with haste, and Appleloosa will be but a two hour journey from there."
Celestia and Twilight nodded just as Luna emerged from the doctor's home with Rainbow Dash on her back.
"Oh, look at that." Discord laughed nervously. "We better get going, right?"
Still facing to Celestia, Meph motioned towards the draconequus.
"The two of us will return to where it happened. We have some things to talk about."
"I understand," Celestia replied, attempting and failing to hold back a grin.
Discord's smile literally dropped to the floor, before he reluctantly sighed in defeat.
From where Applejack and her parents sat, one could see the whole of Ponyville. Tartarus' version, that is. The buildings and streets were all there, only slightly more old fashioned – it was basically the same town.
"It's like looking back in time." Applejack glanced at her parents, who smiled back at her.
"It appears our friends has come to some sort of agreement," Carrot Seed said, as he saw Twilight trot towards them.
Twilight Sparkle approached the three ponies on the edge of the clearing. They were joined in an embrace, and Red Delicious' voice grew stronger as Twilight came closer.
"...care of yourself, lil' Apple. We'll miss you." Applejack slipped out of her hooves when Twilight arrived, and looked questioningly at her mother.
"I'll be back in a jiffy, just gonna follow my friends to the surface," Applejack said, raising en eyebrow.
Applejack must not know she's alive. Discord's earlier warning echoed through Twilight's mind, and she reluctantly held her tongue. Applejack's parents exchanged knowing glances with Twilight, before saying that they would wait there for Applejack's return.
Celestia and Luna, with Rainbow Dash on her back, stood by the tunnel when Twilight returned with Applejack. Meph and Discord were nowhere to be seen.
"They left," Luna explained, noticing their searching glances. "Mephistofilly did not look... pleased."
Celestia took a step towards the tunnel, glancing inside.
"She did mention that this will only be open a short while before closing, though, so we need to hurry."
She stepped inside, quickly followed by Luna. Twilight gave Applejack a reassuring smile before following the other two princesses. Applejack raised a hoof enter, but she hesitated. A feeling that something was wrong was nagging at her heart. Shrugging, she shook it off, before waving goodbye one final time to her parents. She then delved into the darkness after the others.
Twilight Sparkle heard the galloping hoofsteps of Applejack approach from behind, before slowing down and trotting next to her. Twilight shot a glance at her friend. Applejack's eyes were focused straight ahead on the rainbow mane that swung to the steady rhythm of Luna's steps, and she wore a solemn yet determined expression.
Nopony in the group said anything as the tunnel went on and on, constantly upwards. The low ceiling gave a sense of being trapped, and Twilight had an urge to use her wings to just fly out of there. She was beginning to understand why Rainbow Dash spent so much time flying: such freedom. Then again, the low ceiling prevented such a thing, and the group trotted onward in silence.
After what felt like forever, Twilight Sparkle saw the faint light that was the end of the tunnel. The others apparently noticed it, too, and the group let out a sigh of relief. But that feeling didn't last. The earth around them shifted slightly, and a brief rumbling sound echoed through the tunnel.
"It's going to collapse!" Celestia called out. "Run!"
The light quickly grew closer, and despite that the rumbling had ceased they didn't dare stop their gallop. They burst out into the open and stopped when a safe distance was between them and the tunnel, heaving for air.
"I have never been happier to see the sun..." Celestia breathed, glancing to the sky before straightening herself. "But there's no time to lose."
"What about Discord?" Twilight asked between her gasps for air, concerned.
"He will manage. He always does." Luna glanced back over her shoulder, and her eyes widened in chock.
"Applejack, get away from there! The entrance will collapse any minute!"
Applejack wasn't moving.
"I can't come with you."
Realization dawned upon the three princesses just as stone around Applejack slowly came to life again, rumbling ominously.
Celestia took a step towards her, only to find her hoof hindered mid-air by some sort of force field. The path was closing, and no living pony was allowed to enter.
"Applejack!"
"I have led a happy life, but it's time for me to move on..." she gulped, angrily blinking away a few tears. "Y'all must go to Appleloosa..."
"It's not like you think, Applejack!" Twilight shouted in panic. "You're not-"
"You can't save me!" Applejack screamed. Even the moving stone seemed to go silent as her words echoed across the landscape. Tears were streaming down her cheeks and her eyes rested on Rainbow Dash, who had muttered something in her unconsciousness. "Head to Appleloosa. And... tell her I loved her."
With that, Applejack turned and bolted into the darkness, the sound of her sobs quickly fading.
Celestia and Twilight cried out and gave chase, only to be stopped and thrown back by the invisible barrier. Luna simply stared in disbelief where Applejack had stood.
The three princesses could only watch in vain as the earth screeched and shifted, leaving nothing but solid stone where the gates once had been.