//------------------------------//
// Interlude Chapter: Underground 
// Story: "Princess Flurry Heart, Destroyer of Worlds!" 
// by Fluttercheer 
//------------------------------//

	As the wheels of the train hit an unexpected bump on the tracks and the train car was shaken by the impact, Rainbow Dash's head shot up. Frantically, her eyes darted around, but all they found was darkness.
Without orientation, the pegasus mare jumped up from her seat. Immediately lowering her head and flaring her wings, she took on a battle position. She clenched her teeth while continuing to look around, waiting for her eyes to adjust to the blackness that surrounded her and trying to spot something.
Rainbow Dash focused on all her senses at once. “Is anypony here? Tell me what happened! Did something attack the train?” The words came out of her mouth like she was already busy shouting commands during a battle.
All of a sudden, the darkness vanished. The magical lights of the car went on again, as fast as they had went out earlier during Rainbow Dash's sleep. In the door at the other end of the car, the conductor appeared.
“Only a small rock on the tracks!” he gave the mare an all-clear and waved at her, his voice sounding relieved.
Slowly, Rainbow Dash felt how her tense muscles relaxed and she sat down on her seat again. Her head felt still fuzzy and only now she realized that she had been fallen asleep shortly after she boarded the train in the Crystal Empire.
Rainbow Dash yawned. Then she stretched out her tired limbs and flexed them, to free herself from the lethargy. With an unhappy frown on her face, she propped up her head on one hoof and looked out of the window. Her eyes followed rocks entering and leaving her field of vision as the train rode through the dark tunnel, until she began to feel dull and couldn't take it anymore.
Rainbow Dash groaned. “I wish I could still fly all over Equestria, like I used to..... By now, I would already be at the Wonderbolts Headquarter in Fillydelphia, not like this sluggish train.”
She yawned a second time, feeling sleep tugging at her again already. But instead of closing her eyes and taking another nap until she would arrive at her destination, the athletic mare left her seat and began to trot up and down in the train car.
Gradually, the heavy feeling that remained from her nap left her body, making her feel more awake with every hoofstep. What finally drove the sleepiness out of her body completely, though, was none of these steps and neither one of the continued stretches and flexes she did.
In one moment, as her constant trotting had just brought her to the middle of the empty train car again, the train slowed down when approaching a curve of the dark underground tunnel and, through the window to her right, Rainbow Dash's gaze fell upon something that let her pupils shrink and her mouth gape open in shock.
Emerging from the window's right side as the train passed by it slowly, a sign came into Rainbow's view; a white, metallic sign, attached to the wall of the tunnel and lit up by one of the tunnel's lamps above it; its rusty marks indicating that nopony had use for it anymore since years. But despite the rust on its surface, it was still very much readable.
The scar under Rainbow Dash's left eye began to hurt suddenly, as she read the words out aloud.
“Canterlot,” she muttered.
Her eyes followed the sign like in trance as it got seemingly pulled to the left through the train's constant movement. As it had almost left the window frame, something else came into view:

A gaping, black hole.

It was another tunnel, a different track leading into its darkness. Right behind the entrance, a strong barricade made of wood blocked the tracks, making every ride into the tunnel, something which only a train driver who had lost all his senses would attempt, impossible. In the barricade's center, another sign, a yellow one, was fixated. “Dead Track” its bold, black letters said.
Rainbow Dash held a hoof at her scar as it began to hurt more.
A multitude of memories suddenly dropped themselves on her mind at once while her eyes were locked on the words. The pegasus began to shiver and, feeling like her hooves could not carry her weight any longer, she turned around and trotted back to her seat with wonky steps. Sitting down on it, a wheeze left her throat.
Still feeling pain in her scar, Rainbow Dash looked out the window again, her eyes, that now appeared as dull and distant, focused on the rocks in the tunnel wall once more.
In this position, Rainbow Dash remained, and she did not move one inch until her arrival in Fillydelphia, her mind being haunted by the demons of the past.....