Fluttershy wasn't all that fond of conflicts. But she tended to be very protective of her friends- and vice versa.
Which, one could argue, made her surprisingly lethal. Because Fluttershy made a lot of friends.
Twilight was examining the gem.
"One of your animal friends found this?"
Fluttershy nodded.
"...Jasper had been gone for a few days. I was starting to get worried. Then he showed up with this. I think he is trying to tell us something."
"What do you think, Spike?"
I think it looks delicious, Spike thought, but I guess this isn't especially helpful. Besides, one gem would already be one too many.
"Gems are a special drug made for creatures who can be controlled with them, they're actually quite common throughout the facility..."
"...I don't think he found this one in Cloudsdale."
Twilight's face lit up.
"So he can lead us to an other area! This is not a dead end!"
"But why a gem, of all things?"
"Guess we'll find out if we follow him. Fluttershy, can you ask him to show us the way?"
"...I'm sure Jasper would love to help."
The ponies were staring down the giant well under Cloudsdale.
"...Uhhh... Down there? Are you sure, Jasper?"
The little animal nodded.
"...Jasper has been climbing along the wall. I don't know how far down one would have to fly..."
"No problem", Rainbow Dash said, "He can lead the way, and I'll follow. Then I'll come back to tell you guys what we have found."
Jasper was fitted with a little lamp so that Rainbow Dash wouldn't lose him in the darkness. Rarity saw the blue pegasus' expression and quickly put together a lamp helmet for her as well.
Before Rainbow could follow him, Applejack hugged her tight.
"Promise me to be careful, Rainbow."
The blue pegasus blushed.
"Gosh, Applejack. You know me. I'll be fine."
Rainbow Dash was descending into the darkness, slowly, her eyes on the little moving light on the wall.
She was in a vertical position, her hind legs dangling over the abyss.
I am not scared, she told herself, I am just on my hoofs. Or wings.
This feeling of vastness... Your mind was filling it with all kinds of horrors, but for some reason, the thought that there was nothing but emptiness was just as scary as any monster. The void has eyes...
Rainbow Dash shivered. Great. So now she was scaring herself. Part of her considered giving up and begging other pegasi to come with her. But since she was the guardian of the element of loyalty, this motion was rejected almost instantly.
After what felt like an eternity, Rainbow thought she heard water, and still a bit later, she was positive about it.
She now discovered countless pipes protruding into the abyss, some of them vomiting wastewater.
The air had become even colder, and the humidity was rising exponentially.
Rainbow gasped. She didn't dare to descend much further, and her helmet lamp wasn't strong enough to give her the full picture from up there, but Rainbow knew enough. The giant well ended right on top of an underground river. And not a very tame and cozy one, it would seem.
That makes sense, she thought, sort of. They were using this as a natural sewer system. All the... stuff falling down from Cloudsdale or flushed in from the other towns would end up here. And I bet further up the river, they have a point where fresh water is pumped into the facility... But where did that little critter...
That's when she realized she hadn't been paying attention to Jasper anymore. For a brief moment of panic, Rainbow thought she had lost the tiny light, but there he was, on some sort of platform carved into the stone of the wall. And there was a door.
"Great job, Jasper!"
After Rainbow Dash had returned to Cloudsdale, the six fillies and their dragon companion prepared the second expedition. Twilight Sparkle had developed a spell that would allow them temporarily to walk on a vertical surface, but everypony agreed there was no use putting all eggs in just one basket, especially if the hundreds of other ponies were supposed to follow them later on. So they decided to put the tools Rarity and Pinkie Pie had created to the test, including a prototype elevator powered by unicorn magic or, alternatively, earth pony muscle. They could have started sooner, but Rarity had insisted on changing the design of the miner's helmets last minute. With the battle for Cloudsdale still on everypony's mind, no one thought crossing Rarity was a good idea. Speaking of good ideas...
"Fluttershy... do you think this is a good...?"
"...They insist on coming with us. I don't think they will be much of a burden."
All of the surviving dark troopers fit enough to move had gathered at the well and were preparing what seemed to be their own climber's equipment. The ponies still wouldn't allow them to carry their knifes and firearms, however.
"Sure, but they said themselves they don't know much more about this place than we do... And besides..."
"...They won't try to hurt us again. I just know it. Please, Twilight. They just want to help."
Twilight Sparkle still wasn't sure about this. It was good to have allies, but these creatures...
"...Please Twilight, trust me."
That, of course, sold the deal.
On the other side of the door near the bottom of the well, there was a cave. Some of it might have been natural, part of an ancient cave system linked to the subterranean river, but most of it was clearly carved into the bedrock artificially.
Fluttershy shrieked.
Twilight turned around just in time to see a hissing beast leap out of the shadows, slashing at the yellow pegasus with its claws.
Before the attacker could inflict even more damage, one of the dark troopers jumped him, and together with three of its fellow monsters, managed to keep him down.
The trooper on the creature's belly was lifting up its arm, a sharp piece of rock in its hand, ready for the final strike.
"NO!"
The trooper's hand stopped mid-air. Fluttershy got back on her hooves, while Rarity dashed forward to see to her wound.
"... Please don't hurt him..."
Twilight thought that it would have been interesting to see the trooper's expression, but of course the helmet covered its face completely and permanently. What was clear though was that the humanoid was trembling- in what Twilight assumed to be pure rage.
"Are you okay, Fluttershy?"
"...It's just a flesh wound. It isn't all that deep..."
The three bipedal creatures continued to hold the stranger down while the ponies came closer to examine him.
"Well what do you know. It's a diamond dog."
"He doesn't look so good..."
The dog was shaking and growling, the eyeballs almost rotating in their sockets. His mouth was full of foam, and he was babbling hardly intelligible nonsense in a constant stream.
"What do you suppose is wrong with that fella? Besides he being a diamond dog and all, which is a pretty bad affliction in itself..."
Spike was shaking his head.
"'Diamond dog' is just a name, Applejack. Just like 'pony'. Inside, you're pretty much the same thing. They're hairier, you're hoofier, that's about it."
Applejack shuddered. She felt the need to double-check.
"So let me get this straight: we're part dog."
("Warf."
"Rainbow? Why is your tongue hanging out...? Oh no... You... RAINBOW NO! BAD GIRL! Not now! Don't come any closer! I'm warning you, young lady, I..."
Slobber.
"Now that's just peachy.")
"That's very romantic, girls, but let's focus on the issue at hoof, shall we?"
("Hey! She was the one who started fillyfooling around!"
"Did I ever tell you you taste delicious?"
"Frequently."
"Well, I'm happy to declare it is still true.")
"I'd say this guy suffers from gem-withdrawal", Spike said, "Diamond Dogs are completely dependent on that stuff. Maybe we should give him the gem Jasper found..."
"Oh, that's just great. Let's fuel the junkie. That's the moralthing to do."
"I'm just saying, this way he might calm down for a while."
It was not a pretty sight. As soon as the dog had the gem in his claws, he started to slobber all over it, making noises so obscene Applejack put her front hooves on Rainbow's ears. But Spike was right: from one second to the next, all aggressiveness had disappeared. The troopers still wouldn't let him out of sight, of course.
After the dog had calmed down a little, Twilight said:
"Alright. That's enough of that, Mister."
She magicked the gem out of the dog's claws. The expression on his face was priceless.
Instead of attacking, he was falling flat on his belly in front of the purple unicorn.
"Oh please, oh great and mighty and oh so beautifulunicorn lady, givse us back the preciousss!
"Listen, I..."
"Oh please, meese begging your highness with all the emotion in my little, rotten heart! Please givse back the star of my lowly life, or I shallse surely die..."
"Listen to me, man. You can... lick this particular thing all you want, but first we have a few questions for you."
"Allse the questions in the world, ask them to me, and I will answer, oh yes, answer I will like a..."
"Thank you."
They learned that the dog had been lurking aimlessly through this labyrinth. He had been cut off from the other dogs by a tunnel collapse not far from where they had found him. He was too weak to try and dig back to the main cave.
He agreed to lead the ponies through the tunnels. He would have agreed to anything, as long as he had the gem.
Though Fluttershy wasn't hurt all that bad, the troopers insisted on carrying her on their shoulders, at least for a while.
Spike couldn't help but admire her influence on the creatures.
"Good job on reprogramming these guys, Fluttershy!"
"...I didn't do anything. But I'm glad they are offering their help."
She noticed some of them were moving in an increasingly odd, sluggish way. As one-way drones unable to feed, they were running out of nutrients.
They had reached the site of the collapse, and everyone helped to get the tunnel free again. Well, almost everyone.
"Would it kill you to lend us a hoof?"
"Awww, Aplpejack, I already dida lot of things! I flew down the well, I found the door... And right now, even though I'm exhausted from my exploits, I'm keeping you company, giving you moral support- that's important. You should thank me."
"I'll thank you as soon as I can see you diggin' like everypony else, sugar cube."
"That's no work for a supersonic pegasus! It's all heavy... and slooooooooow. You're all muscles, and you love digging, right? You do what you do best, I do what I do best. Everypony wins."
"Rainbow, you come down here right now..."
"Jawohl, Fräulein Apfeljack! Schtupid pegasus ist LAZY! You teach her a Lektion!"
"Girl, if you think you can wriggle your way out of this with another guilt-trip..."
"What's gonna happen?"
"You might wanna start looking for a new tent to sleep in this evening."
"Grrgl."
"Glad you see it my way."
At first glance, the new set of tunnels didn't look all that different from the area they had just traveled through, but after a while they could hear the moaning. The diamond dog guiding the group started to whimper and pressed the gem tightly against his chest. If it weren't for the troopers watching his every move, he even might have tried to run off.
"Say", Twilight wondered, "You don't seem all that happy to go back home."
"Oh powerful and beautiful, gem-giving unicorn lady, whatse is the use of home if there are no gemsss? And ssso many thirsssty dogses?"
"Thirsssty...?"
"For gemsss!"
"Right..."
The bipedalians were now going ahead, weary of new potential attackers.
"Stay back", the one with the bandage on his legs said, "There are many lifeforms ahead. We will observe the situation." It was so rare to hear these beings speak that it made Twilight jump.
A few minutes later, one of the dark creatures made a hand sign that it was safe.
The ponies were staring at a living lake of miserable, diseased dogs, rolling and shaking on the ground.
"Are they... chewing on one another?"
"I'm afraid so. Sometimes the drug enters the skin and the hair and stays there for weeks... And so they go after it."
Perhaps the most surreal element of this scene was a dog standing in a corner outside the crowd. Though as sickly as the others, he was wearing a black suit, and seemed to be sniffing dog hairs through a straw.
"Well, that's dumb...", Pinkie Pie jumped right into the hairy sea, "What do you think you're doing, you... dogs?"
"We're having a partiiiiiiii...", one of the dogs squeaked.
"That's NOT a party! Parties are supposed to be about FUN, and FRIENDS!"
"We are fwiendsssss..."
For the first time in days, the dog was actually looking at the akinetic guy who's feet he had been chewing on.
Despite all the horrible things the ponies had seen so far, they were not prepared for what they were seeing now: this particular dog didn't even have fur anymore. In fact, even most of his skin...
Though she did her best to be silent, they could all hear Fluttershy sobbing.
While the ponies were terrorized by this sight, Several dogs had smelled the gem carried by their guide. Before the two troopers guarding him could react, dozens of arms were rising up from the furry mass and pulled the poor, screaming diamond dog as well as his treasure into their midst. A few seconds later, there was a collective burp.
Still under shock, Twilight decided to talk to the dog in the suit. Maybe he was the craziest of them all, but hey, he was wearing a suit. That had to count for something.
"Tell me... Sir... What is going on here?"
He wasn't listening to her, so she knocked the straw out of his hand.
He hissed and flashed his fangs, but two laboratory troopers grabbed his arms.
"Please. We need answers."
The dog seemed to relax somewhat.
"We're supposed to dig. Create more caves. Do the Dungeon Master's bidding. He used to give us food, and gems, but for some time now, he only hands out gems to the strongest workers. And he hasn't fed us for ages..."
He sniffed. "We're mostly concerned about the gems, though."
"You don't say..."
"Caves like this one are for those who aren't strong enough for digging anymore."
"How do we get out?"
"You don't. There is only one exit- in the Dungeon Master's throne room..."
"Then this is where you will lead us."