Imagine an elevator.
Now remove the doors, add a pony-sized 40kJ battery by its side, and put a lever interface on the other side. That was what the transit tube access looked like, exactly the same all across the colony.
Twilight Sparkle was standing in front of one such tube access, grumbling and tapping her hoof impatiently at the innocent flooring she's standing on. There was a Dupe between her and the tube access, though, trying (and failing) to engage her in a conversation, so that statement isn't exactly accurate.
Let's try again: Twilight Sparkle was standing in front of a Duplicant that she didn't remember the name of and frankly didn't need to for the lack of interest she gave for the biological lump of manufactured Ooze, which made it safe to say that she's standing in front of a transit tube access point with an insignificant socially-inclined meat popsicle in between.
"Hello? I was talking to you!"
"Oh, is that so? Sorry, I was too busy ignoring you to notice."
The yellow pegasus guffawed, as did Rainbow by her side. It's almost comical to see their similar caps bobbing in synchronicity. "I like you already, newbie!"
"I would like you to refrain from calling me that in the future, Miss."
"And you can call me Spitfire."
"Thank you. I'll try my best to forget it as soon as possible."
Another round of giggles, and a dejected sigh from Twilight. After what felt like forever, Twilight looked up to Spitfire again. "Where is she?"
Spitfire rolled her eyes. "Stuck somewhere in the tubes, probably."
A ding! made the pegasus look back and Twilight to look up. A Rainbow Dash trotted hurriedly toward them with a wrangled slickster on her back and a drowsy look on her face. "Sorry, sorry!" she said drowsily before yawning. "Fell asleep right before the tube access on the other side. Here's the other slickster."
Rainbow Dash took the slickster from her copy and gave it to Twilight, for she was already carrying one previously carried by Spitfire. Twilight took it and immediately trotted away.
Rainbow looked guiltily at the Spitfire. "Sorry, she's kinda impatient."
Spitfire shook her head. "Nah, don't worry about it." A pause, then, "Say, are you narcoleptic?"
"No, why?"
"Oh, just wondering."
Rainbow nodded and adjusted the wrangled critter on her back. "Alright, then. I'd better catch up. We're already behind schedule as it is."
Spitfire tipped her courier hat labeled 'Oil Ravinery'. "See you around, Crash."
Beside her, Crash snapped her head upward. "Bwuh? Wazzat?"
Dash chuckled and tipped her hat labeled 'Bristle Acres'. "See you around, Spitfire." She turned sideways and nodded at Crash. "And you, Crash. Good luck with your sleep schedule."
As Dash trotted away and disappeared behind a corner, Spitfire turned toward Crash. "Say, Crash, do you know what her disability is?"
Rainbow Crash shook her head. "Nah. Why?"
Spitfire looked back toward where Dash disappeared. "No reason, really." She shook her head and sighed. "No reason. Let's get back to Oil Ravinery before you fall asleep."
Rainbow Dash opened the door to the stable on floor 237 with Twilight trailing behind her.
A yellow pegasus mare with an orange-banded rancher's hat greeted them. Or, more accurately, she attempted to greet them both with such little voice that neither heard what she said.
Twilight raised an eyebrow. "What was that?"
She shrunk back. Looking through her pink mane, she said in a louder voice, "H-hello. I'm Shy."
Twilight rolled her eyes. "I can see that."
Rainbow Dash, somehow already putting away the slickster somewhere somewhen, grabbed the yellow pegasus by the withers and pulled her up, despite her reluctance. "What she meant to say, is, her name is Shy."
"Alright," Twilight said, "Where should I put this thing, Shy?"
Shy pointed one of the doors on the far side of the room while mumbling something.
Twilight nodded and trotted away, leaving Rainbow to have a friendly chat with Shy. As she opened the door, she was greeted with the thick smell of oil and another yellow pegasus with a similar orange-banded rancher's hat.
The yellow pegasus mumbled something.
Twilight let out an exasperated sigh. "What was that? Speak louder."
The pegasus shrunk back and mumbled something still incomprehensible.
Twilight rolled her eyes and queued a request to look up the Duplicant's bio to the Manager. A few seconds later, her mind was filled with a load of information about Duplicant #2398 "Flutters". She looked back at the pegasus and put the slickster from her back to the floor. "Here's the other slickster you ordered, Flutters. Have a nice—"
A second later, Twilight stood up stumbling from Flutters' forceful shove and glared. "Hey, what was that for!?"
Flutters, still making silly faces and noises at the slickster, ignored her. Twilight breathed a sigh of relief at the avoided social interaction. Turning around, she was greeted by yet another yellow pegasus with a black-banded rancher's hat. Twilight turned around, finding Flutters already brushing the slickster at the grooming station, and looked back at the picture-perfect copy of said carbon-based blob of shyness and lack of self-confidence.
The yellow pegasus mumbled something.
Twilight sighed. "Let me guess. Your name is Fluttershy?"
The yellow pegasus looked up with wide eyes and a smile. As she spoke, her eyes shone with wonder and the reflected light from the nearby ceiling lamp. "You knew my name?"
"Lucky guess, actually."
Fluttershy shrunk back.
Twilight grunted. "Alright, let's get it over with. What do you need?"
Fluttershy perked up. "Oh! Uhm, you came from Regoville Frontier, right? I don't suppose, Uhm, you know what might be holding back the regolith delivery these last five cycles? The shove voles are getting hungry."
"There was an accident involving meteors and incompetent mechatronic engineers. Regoville's currently repairing a lot of stuff, the bunker doors included, which made the surface inaccessible. It should be done this cycle, though. The regolith should come—"
"Hey, Fluttershy!" Rainbow's voice came from the front door of the stable. "The regolith just came!"
Fluttershy squealed and turned around, finding Rainbow carrying two tonnes of regolith from the courier before. "Finally! Oh, the shove voles are going to love this!"
She turned toward the only airlock door—made of steel—in the stable and called, "Shy, the regolith came! Let the shove voles out!"
The door opened, and a diggie of shove voles (that's the correct collective noun) came out, squeaking happily at the sight of boring gray sand on the floor. Shy came trailed behind them, smiling fondly at the sight of cute, innocent pieces of future dinner munching on their brunch.
Twilight stepped back and trotted toward the front door, at which Rainbow blocked her path and shoved her back inside. "Relax, Twi! We're not in a hurry. Enjoy your time with other Dupes; you'll be meeting them a lot."
Twilight grunted at her failing attempt at pushing herself outside. "That's what I'm afraid of."
After a while, Twilight finally gave up. She walked toward the happy shove voles and sat on her haunches. Rainbow stood next to her, talking about some things involving her almost succeeding in flying one time.
At some point during Twilight's struggle for social ignorance, Shy counted the shove voles out loud and mumbled, "Where's the seventh shove vole?"
Crack
Twilight slowly turned her head toward Rainbow. As they locked eyes, Twilight felt her heart stopped and deliberately stopped her breathing at Rainbow's look of terror.
"Don't move a muscle," Rainbow slowly said, reaching out a hoof. "Hold my hoof and slide carefully. Don't stand up."
Twilight slowly raised her front hoof from the ground, stopping mid-way as a loud creak came from below her. She dared not look down, continuing her effort at taking Rainbow's hoof after no more sound came.
Her breath almost ran out, and she breathed out slowly. She took a deep breath and continued moving her hoof toward Rainbow's own.
Two centimeters more.
Another crack. A silent ode of floor crumbling to dust. A panicked scream of terror. A desperate attempt at finding something to hold on into.
Rainbow held Twilight's hoof in a firm grip, thousands of cycles of carrying tons of materials across Bristle Acres ensured that Twilight would never fall from it.
Twilight squirmed and held Rainbow's hoof like the salt hanging from Dasha saltvines. She looked down below, finding a sea of crude oil and a curious look from a shove vole poking out of the remaining floor beneath her.
Rainbow chuckled. "Heh. That was close—"
The ground beneath Rainbow disappeared. Two ponies clinging to one another fell in a panicked fit, screaming all the way until they splashed to the oil down below.
Twilight immediately closed her eyes and held her breath just before the splash. She slammed head-first into the black surface, ears ringing as she felt her limbs went limp and frigid on reflex. She lost her grip to Rainbow at some point and slowly, surely, hopelessly descended deeper into the abyss.
After what felt like hours, cycles, years, she hit the bottom of the oil pit. Her ears felt like it would burst, and she had to hold back her instinct not to take a deep gulp of air, which is absent in place of the unrefined liquid form of dead primordial animals.
And so, there she sat, waiting for something, anything to happen.
A mental nudge came from the Manager. It felt soothing in a way, like a mother's cradle to her terrified child after meeting a clown, but with less clown and more nagging terror of death by asphyxiation. Nevertheless, it relaxed her muscles, calmed her mind, and allowed her a moment of peace.
The Manager gave her another nudge, this time requesting temporary control over her muscular system. She hesitated for a split second before accepting the request.
She felt her hooves moved on their own, her back hooves standing on the flooring and her front hooves stretching outward. She felt herself jumping, pedaling in a swimming motion, slowly, surely, calmly, upward in a slight angle.
Her lungs burned, eager for oxygen. She thought for sure she'd take a lungful of oil, but it never came. Her chest muscles were kept still, her diaphragm obliging to wait patiently for air. It felt surreal, having her reflexes shut down.
Her hoof met with something solid, and she felt herself gripping it tightly. A hoof. It returned her grip firmer.
She felt herself getting pulled by the hoof, her body lurching upward, slowly accelerating.
She broke the surface. Her own mind immediately shot a neural command to take some air, but it was overridden by the Manager's command to stay still and hold her breath. It was still full of carbon dioxide, she noticed after a thought; she wouldn't want that to be breathed in.
The hoof kept pulling her up. She heard the thumping of hoof against ladders, then a pneumatic door opening. She felt herself getting flung upward and landing gracefully with all four hooves on the mesh tile, making so little noise she could still hear the chitter-chatter of the slicksters around her.
The Manager let go of her temporary control, and Twilight fell and went into a coughing fit, spilling out black, sticky oil all over the place. She took deep breaths of sweet, sweet oxygen and curled into a ball. Three pairs of yellow hooves cradled her and held her in a comforting heap of reassurance that she's not yet dead.
The Manager gave her a worried mental nudge.
Twilight shuddered. "Please don't do that again."