the core problem
The hour had grown late in Ponyville, when Spike had called all of his fellow 'liberators' together for a meeting at Kimono's home outside of town. Many equines had come, and they were all currently seated on satin cushions, while Kimono poured them each a warm cup of tea. The oriental pony was, after all, the most generous of hosts. And she would let no pony under her roof go unserved.
"I am so very pleased, that we have been able to draw so many allies to our cause!" Spike said proudly, puffing his reptilian chest out. "But tell me... are there any other communities beneath the dome, who might lend us their aid?"
"There is a reclusive community of elves that live to the extreme northern tip of the dome!" Storybelle offered, sipping her tea. "They are led by an obese bearded elf in a red suit, and give gifts to the Ponyville ponies every hearth's warming eve... which they call Christmas!"
"But I've heard that the elves are very, very secretive, and don't communicate with any of the pony tribes at all!" Kimono added, setting the kettle of tea she was holding down. "They are not very fond of strangers, and Minty is the only pony to even have had something close to contact with them."
"Then I fear we can't count on their help, Kimono." Zipzee added, buzzing around the room. "Isn't there another creature that dwells beneath the dome?"
"Well, there are unicorn tales of a mean looking young goblin, who dwells under the Butterbrook bridge." Cheerilee shivered, recalling the story from her own youth. "His name is Beezin, and he gobbles up ponies who pass over the bridge without paying him a tribute!"
"No offense Cheerilee, but I'm afraid we don't have time to waste on filly tales!" Starsong flittered her wings in annoyance. "We need to come up with a solution to getting out of the dome, here and now, for ponies by ponies."
All of the others winced at the flutter pony's emphasis on that word, well aware of the inherent prejudice the flutters had against other races.
"I believe my subjects and I may have found a solution." Starcatcher added, elegantly sipping her tea. "We have found weak points in the dome's upper sections- the points where the magic field surrounding the region come together."
"How on earth did you find them?" Cheerilee asked, surprised. "I thought Pegasus had no magic!"
"We still retain a bit of the weather magic our ancestors once had." The queen of Butterfly island replied. "The atmosphere at those points are a little less natural- a little more stale, if you will, than the other areas in the upper dome."
"Hmm, if we unicorns could get up there, and apply our magic to the dome's interior..." Cheerilee replied thoughtfully. "We may be able to bring the whole thing down!"
"That's a splendid idea, Cheerilee! A very brillant and clever plan!" Spike told her enthusiastically. "If we all work together, we can be out of our glass prison within a month!"
"Say, Cheerilee, I've heard you had a daughter, named Twilight Twinkle." Storybelle added. "Why don't you have her lead the unicorns in their mission to destroy the barrier?"
"Ummmm.... I really don't think my daughter is best qualified for this job!" Cherilee replied nervously, her eyes darting around the room. "Trust me, magic isn't exactly her strongest suit!"
"Really? Why is that?" Stasong asked, pressing the issue. "I have heard from the other unicorns that nobody ever sees Twilight Twinkle around Unicornia. I've even heard she only comes out at midnight to watch the fireflies dance."
"Leave her alone, Starsong! Cheerilee and her daughter probably have their reasons!" Starcatcher chided. "It's not like Cheerilee's daughter is some other kind of pony or something!"
Cheerilee seemed to go completely pale at that, but Kimono quickly intervened. "All right, that's enough for this week! We'll continue this next week, at Storybelle's house!"
All of the ponies said their goodbyes, and went their separate ways.
"Hey Starsong, want to come back to the story loft with me?" Storybelle asked the flutter pony. "We could read some books together!"
"Nah, I'll see you later, Storybelle!" Starsong waved to the earth mare as she fluttered off. "I need to go get the dancing shoes I left at Pinkie Pie's house the other day!"
"Fare you well, Starcatcher!" Kimono bowed to the graceful Pegasus, as she flew home. "May your trip back to butterfly island be free of incident!"
"Thank you, my good Kimono!" Starcatcher nodded towards the wise earth pony. "May your life be happy and rewarding, until we meet again!"
As Cheerilee trotted out the door, Spike ran to catch up to her.
"Ah! Miss Cheerilee! You are so very far away from Unicornia, and so late at night!" The dragon bowed to her. "Would you do me the honor of allowing me to escort you home?"
"Why thank you, my good Master Heathspike!" The unicorn replied with a laugh. "I would most certainly enjoy the company!" The two left Kimono's house, and started off down the road together.
"So, I hear things are really happening in Ponyville!" Cheerilee asked Spike. "During her visit to Unicornia, Rainbow Dash told me you were able to get two shy earth ponies to come out of there shells... so to speak."
"Why, yes! Toola Roola, the town Painter, and her best friend, Scootaloo. They spent very little time with the other ponies." Spike responded, a smile beaming across his face. "But I was able to get them to start talking to Rainbow Dash, Starsong, and Pinkie Pie. Now they've opened up, and started being more friendly to other ponies!"
Cheerilee nodded. "We have a unicorn in town, named Sweetie Bell, who befriended Rainbow Dash during her visit to Unicornia. Now, wants to move to Ponyville to be closer to her new earth pony friends."
"My word! Those ponies are always doing things together now!" Spike Laughed. "In fact, one could almost call them a core six!"
As the two were talking, they failed to notice two unicorns perched on the ridge above them, watching carefully.
"Here comes Spike and Cheerilee, done with their meeting!" Bright Sprightly Snorted, eyeing the two angrily.
"Remember, we only want to hit the dragon!" Garden Wishes growled, aiming her horn. "Try not to hit Cheerilee, if you can avoid it!"
"I don't see why I should go out of my way not to!" Bright Sprightly growled back. “She annoys me to no end, with her inability to keep Princess Spoiled Brat in check!"
"Well... at least make it look like an accident!" Garden Wishes whispered back.
The two Charged up their horns, and took aim at the unsuspecting dragon.
It was then, that a blue Pegasus came galloping up the road very quickly, stopping in front of the Dragon and the unicorn.
"Oh! Spike, Darling- there you are!" The earth pony fashionista grinned. "I was thinking of having a fashion party, and I was wondering if you had any idea what the theme should b-"
FSHOOM! The two unicorns suddenly fired two beams at Spike... but the unexpected arrival of the earth pony had thrown their aim off. One beam struck Cheerilee dead center, while the other hit Rainbow Dash.
"AIEEEEEE!" Both of them screamed in pain, and collapsing to the ground.
"Dash! Cheerilee!" Spike rushed over to their sides. "Are you all right?"
"Oh no! We hit the mares!" Bright Sprightly yelled in a panic.
"Let's make a run for it!" Garden wishes exclaimed, as the two galloped away before Spike could see them.
"Oh, Spike! What happened?" Rainbow Dash woke up, and shook her mane in confusion. "What happened to- wait, my voice! What's happened to my voice?"
As soon as the blue earth mare had opened her mouth, Spike was shocked. Dash's accent, and her 'darling' exclamation, were suddenly gone, and her voice had become a high pitched squeak!
"Rainbow Dash! Oh no!" The dragon panicked. "You must have been hit by a unicorn spell!"
Spike looked around, hoping to spot the unicorn who had cast the spell that scrambled the speech center of Dash's brain, but the dragon saw no sign of anypony.
"CHERILEE!" Rainbow Dash suddenly let out a shriek. "What happened to you!?!"
"Rainbow Dash, what are you..." But as the unicorn pulled herself back up to her hooves, she discovered that more than just her voice had changed. "My-my horn! WHAT HAPPENED TO MY HORN!"
As the two ponies started to cry, a bewildered Spike just stood there, speechless. Dash's voice changed, Cheerilee turned into an earth pony... who could have been behind this madness?
"Oh no! Losing your horn!" Rainbow Dash said in a panic, as she and Spike helped the disoriented Cherrilee up. "Oh, you and your husband and daughter just have to come and stay with us in Ponyville, until we get this all figured out!"
"Hm, seems like these two are helping each other cope well enough" Spike mused, forming coherent thoughts again. "But it looks to me like the Ponyville core six, just may have become the core seven..."
...
"This is terrible, Wysteria!" Pinkie Pie exclaimed to her princess. "Just as Puzzlemint has informed us she's ready to identify the two earth pony culprits, two unicorns hurt Cheerilee and Rainbow Dash! Pony has NEVER hurt pony before!"
"They were aiming for Spike, I'm sure of it!" Wysteria replied, pacing back and forth in the main hall of celebration castle. "But this proves that they are perfectly willing to hurt their own kind, in order to get at our dragon friend."
"As per your orders, I've given Cheerilee a house to live in here in Ponyville, for as long as she wants to stay." Pinkie Pie informed her. "And I've received word from Unicornia that Lily Lightly will be taking over Cheerilee's duties as Rarity's royal advisor."
"And what of the two unicorn traitors?" Wysteria asked. "Have they been identified yet?"
"Lily believes them to be Garden Wishes and Bright Sprightly, as they were the only two unicorns totally unaccounted for that day." Pinkie Pie responded. "And judging from the direction the beams hit the two mares from, the they must have fled to the southwest."
"The only thing that direction is Butterbrook bridge." Wysteria shook her mane ruefully. "And if they went that way, a worse fate than anything we would even dream of doing awaits them..."
...
"It's okay, Bright Sprightly." Garden Wishes gasped for breath. "I think we got away from them!"
The two unicorns stopped on the Butterbrook bridge, both exhausted from galloping. It was evening by the time the two decided to rest for a moment.
"The others are not going to like this!" Bright Sprightly wheezed. "We were supposed to mess the dragon up!"
"We'll get another chance, don't you worry!" Garden Wishes snorted, finally getting her breath back. "Besides, those two earth pony dancers failed to hurt him on the roller coaster already, didn't they?"
"We need to get back to Unicornia, now!" Bright Sprightly replied. "And warn the others what has occurred!"
"Well, well well... what have we here?" A sinister sounding voice rasped. "Two little lost ponies... who have stumbled onto my bridge!"
A hideous, green humanoid form slithered up from beneath the bridge- long, sharp fangs, and yellow glowing eyes glaring at them. The two unicorns, still too exhausted to use their limited repertoire of magic, quivered in fear.
"W-what is that?" Garden Wishes asked, terrified.
"I-it's Beezin!" Bright Sprightly whinnied in a panic. "He's real!"
"You unicorns have nothing to pay me tribute, I see!" The goblin, clad in tattered rags and wreaking with the stench of unwashed filth, extended a green bony hand. Fingers with long, uncut fingernails wore several gaudy rings- tributes from Ponies who had survived him, no doubt. "It's just as well... seeing as I was hungry tonight, anyway!"
The two unicorns screams echoed throughout the Ponyville region that night.