This chapter was written by cooopercrisp.
A blinding flash appeared in the plains, and three princesses and one draconequus appeared. They galloped to the entrance to Tartarus, knowing it was there without being able to see it. Celestia knocked on the invisible gate.
"Mephistofilly!" she shouted. "This is Princess Celestia. Open this gate right now!" The three princesses waited for some kind of response, but nothing happened.
"That's odd," Celestia said. "She's never ignored me like this before."
"Perhaps you should have asked nicely," Discord said with a wry grin.
"This is no time for jokes, Discord," Celestia said. She stared at the entrance, pondering. "We're going to have to force our way in."
"But sister," Luna said, "that would be incredibly dangerous. With the gate to Tartarus open, the dead might be able to walk free."
"The dead are nowhere near the gate," Celestia said, "so they would never realize that there would be a way out."
"But is it even possible to break through the gates of Tartarus?" Luna asked.
"Yes, how do you propose to enter the land of the dead?" Discord asked, unable to suppress a look of glee on his face.
"I believe you and I have the capability to do this, but it will be dangerous. Twilight, Discord, I suggest you step back." Twilight did as she was told while Luna and Celestia bowed their heads, their horns glowing with an ephemeral aura. Their magic surrounded the gate, so that Twilight could actually see its shape outlined in yellow and midnight blue. Discord summoned comically large earplugs and shoved them into his ears.
"You might want to cover your ears," he told Twilight. Twilight did so and lowered herself to the ground. Suddenly there was an explosion as the gates blew open. Dust blew through the air, blinding the four of them for a moment. Once it settled, they looked to find that the way to Tartarus was now open.
"There's no time to lose," Celestia said. "Let's go." The four of them galloped into the cold depths of Tartarus without looking back. A chill wind blew through their coats while their eyes tried to adjust to the stifling darkness. Twilight had seen the inside of the entrance when she had led Cerberus back there, but had never found herself inside it.
Wait a minute, Twilight thought. Something's wrong...
"Where's Cerberus?" she asked. The other three stopped and turned, looking around the cave. There was no sign of the three-headed dog anywhere.
"Maybe he went to fetch the paper," Discord suggested. Luna huffed.
"We don't have time to look for him now!" she said.
"My sister is right. Applejack and Rainbow Dash are in grave danger. We need to reach them as quickly as possible." The four of them set off again, the dark path sloping steadily downward. As they plunged further into the depths of Tartarus, they started to smell a rotten odor. Twilight didn't want to know what the source of it was, but Discord and the other two princesses knew it belonged to a terrible creature that lurked through the dark caves. Celestia had only ever seen it once, when it had escaped from Tartarus and wreaked havoc over Equestria so many centuries ago. The fiery gaze of its stare had been enough to terrify even her.
Don't think about that, Celestia told herself. They kept moving, but Twilight was now starting to lose her breath. They stopped at a crossroads with five separate openings to choose from. Twilight gazed at each opening and despaired.
"How are we supposed to find my friends like this?" she asked, gasping for air. "This place is a maze. They could be anywhere!"
"Twilight," Celestia said, "you have the ability to harness the energy of the Elements and track them using your magic. I suggest you use it now so we can find the correct way to go."
"How do I do that?"
"Just focus on finding your friends, and the spell will lighten your path." Twilight concentrated hard on Applejack and Rainbow Dash, and the memories of them flooded through her. She saw Applejack with large bags under her eyes trying to buck an entire orchard of apples by herself. There was Rainbow Dash, looking hurt as her friends revealed that they were the Mysterious Mare-Do-Well. She saw Applejack and Rainbow Dash at one of Pinkie's parties, gazing into each other's eyes and talking animatedly, the first time Twilight had suspected that they were in love. Suddenly, her horn glowed, and orange and blue streaks appeared on the ground trailing outward down one of the caverns into the darkness. The orange streak was bright and vibrant, but the blue streak was very pale.
"Oh no..." Celestia said.
"What?" Twilight asked, mortified.
"Rainbow Dash's light is almost out," she said grimly. "We need to hurry." Now the four of them galloped at breakneck pace, following the path of the streaks. Their heartbeats raced as adrenaline pumped through them. Even Discord looked serious, showing Twilight that he was also concerned for her friends' safety. Twilight smiled, but the smile did not last.
Twilight saw many paths branching off of this one, and the streaks of her friends took them around all kinds of corners and down further beneath the surface. They glowed stronger as they moved, although the blue one was still quite pale. That must mean we're getting close, Twilight thought.
Suddenly, they turned a corner and in the distance they saw Rainbow Dash laying on the floor of the cave with three ponies watching over her. Twilight gasped in horror; her friend looked close to death. The four of them raced forward. Next to Rainbow Dash, Applejack stood alongside a ghost-white filly Twilight didn't recognize. The sight of her alarmed the princesses though. The four of them heard the voices of Applejack and the white filly echoing off the cave walls as they approached.
"...the new deal is this: you and your parents get to live again. So does your marefriend, who doesn't die from her injury. Your sister and brother are alive and well."
"So what's the catch?" Applejack asked.
"The catch is...I get your soul. And with it, the Element of Honesty. So as soon as you die up there, you come down here. And you won't get a cushy life either, like these other dead ponies do. Maybe I could send you to help Cerberus? Yeah, that'd be perfect!" Meph stuck out her hoof. "Deal?"
Applejack stretched out her own hoof, looking like she was going to make the deal, when the princesses and Discord caught her eye.
"Stop!" Luna cried. Applejack, Meph, and the three ponies overlooking Rainbow Dash all turned to them. Applejack was stunned to see them. The three ponies recognized the princesses and had their brows furrowed. Two of them struck Twilight as looking very familiar. She recognized them from the photographs in Applejack's family album.
Those are Applejack's parents, Twilight thought. But...how is that possible?
Meph, rather than look surprised at the sudden entrance of the three princesses and Discord, withdrew her hoof and looked around frantically as if trying to find an escape. Celestia stepped forward, making her cringe, but the princess turned her attention to Applejack.
"Applejack, you are not to make a deal with this filly. I will not have you hand your soul over to the queen of the dead."
"But Princess," Applejack said, "I don't have a choice!"
"There is always a choice, Applejack." Luna nudged her sister.
"Celestia, there's something wrong here," Luna said darkly. Everypony turned to her.
"What is the matter, sister?" Celestia asked. Luna pointed an accusing hoof at the white filly. She cried out in her royal Canterlot voice.
"You are not the real Mephistofilly!"