As magical creatures go, the parasprite’s art direction might be even lazier than the Cerberus’s. It consists of one sphere, blue, perhaps the size of a tennis ball, and two smaller balls superimposed on top colored green so you know they’re eyes. Add some vaguely insectoid wings and legs, and you’re done.

Doesn’t sound very threatening, does it? Certainly Rarity and Fluttershy find something charming in its big-eyed simplicity. Applejack, Pinkie Pie and Rainbow Dash are less taken by its cutesy-wutesy appeal. But you would be hard-pressed by reference to the parasprite’s appearance to explain why Twilight Sparkle is standing fore with her horn ready to fire or why she is shouting at the other ponies to flee.

Parasprites aren’t strong. They are fast. But what really scares Twilight is that parasprites lie…sometimes. It’s hard to tell. They confuse ponies and get them all mixed up.

One pony alone is weak. Only when they work together do ponies become capable of great things. Twilight calls it specialization and the division of labor, cooperation and exchange pushing ever-outward the extent of the market. The other ponies call it friendship.

What concentration of lies can a friendship survive? If I told you the answer was as low as ten percent…

…I’d be lying. And that would make the rest of this story rather useless as anything except entertainment, wouldn’t it?

That’s the point. And remember, all of this is

Just.

One.

Parasprite.

“Pinkie, take the girls and get out of here!” Twilight kept her glowing horn pointed level at the floating blue Parasprite. “Run!”

“Twilight, why are you so frightened?” Rarity sounded alarmed. “Look at the poor creature, it’s harmless.”

“No,” Twilight said. “It is very, very dangerous.”

“Then we’ll help you,” Rainbow Dash said.

“No! It’s more dangerous the more of us there are.”

"Twlight," Pinkie Pie said, "I know the forest is scary, but I think you may be overreacting just the teensiest—"

“I’m not! I need you all to go! Now! I’m the only one who can fight it!”

“Listen very carefully, Twilight Sparkle,” Princess Celestia said. Twilight pulled her eyes away from the princess’s flowing mane that looked like the pulsing nebulae in Twilight’s telescope and focused. “As an economist you will go on many journeys and face all kinds of dangers, and through these trials you will grow. There are, however, a few threats, a very few, which you must never try to fight but instead flee as fast as you can and find me. These are the draconequus, though I pray you never meet one, other Alicorns, and the parasprites….”

That’s not an option now, Princess, Twilight thought grimly. My frie—I mean, my specialized cooperation partners—are standing behind me. I have to prote…guarantee the completion of our contract.

And if I’m going to face your sister, I need to get stronger.

“Please,” a trembling voice said. Twilight started. It took her a moment to realize it was the parasprite. “I’m so hungry.”

Twilight readied a laser from her horn. “I’ve got something for you to eat.”

“No!” Fluttershy threw herself in front of the parasprite. “You can’t hurt it!”

“Fluttershy, get out of the way!”

“No! It hasn’t done anything to threaten us. You should be ashamed of yourself, Twilight Sparkle!”

Fluttershy smiled and cooed softly as the parasprite’s legs touched her head. She giggled. “It likes me.”

“Fluttershy, I need to destroy it!” Twilight said.

“Oh, shut up, Twilight!” Applejack said. “You’re about the most untrusting pony I’ve ever met. Shame on you!”

Twilight turned, startled, to Applejack, who looked equally shocked. "Hold on y’all, that wasn’t me—"

“It’s gorgeous, really,” Rarity said. “We should all be so lucky as to have a parasprite of our very own like Fluttershy.”

“What?” Rarity said. “That wasn’t me!”

“It’s the parasprite,” Twilight said. “Everything it says is a lie.”

“Was that you,” Rainbow Dash asked, “or the parasprite?”

“It was the parasprite.”

“Uh, was that you or the parasprite?”

“It was the parasprite,” Twilight said. “But before it was me!”

“Idiot,” Twilight’s voice added. “But of course you can’t keep up with an academic like me, Rainbow Dolt.”

“Hey!” Rainbow Dash said. “I may be a dropout, but I’m not stupid!”

“Actually, Rainbow, you kind of are stupid,” Applejack said. “No, I didn’t mean that! You’re really stupid.”

"Applejack! What—"

“Wait, I didn’t insult you,” Twilight said. “It was the parasprite. If I wanted to insult you, I’d point out how much of a coward you were earlier, jumping into Fluttershy’s hoofs like a frightened little baby.”

“Stop it, all of you!” Rarity said. “Am I the only one here with any class?”

“Probably!” Rainbow Dash shouted. “Since you’re the only one here who’s so snooty!”

Twilight wasn’t even sure if that was the parasprite or the real Rainbow Dash talking. It didn’t matter. She took aim at the tiny monster floating just above Fluttershy’s head. “Fluttershy, duck!”

A beam of lavender magic burst from Twilight’s horn. Fluttershy barely had time to flinch before the blast struck the parasprite and threw it backwards.

“No!” Fluttershy screamed. “What have you done?”

But the parasprite didn’t vanish or lay dead. It…no, they rose from the ground. One blue parasprite and one red. Even as Twilight reader another beam, they multiplied again. Now there were four—no, eight. Green and purple and—make that one hundred and twenty eight, brown and orange and—

“Oh, no.” Twilight felt her heart plummet through her stomach. She turned to the other ponies. “We have to run, now!”

“Run toward the parasprites!” she added.

“That was the parasprites talking! Hold still, they want you to run!”

“I’m not afraid!” Rainbow Dash swooped toward the growing swarm of parasprites and was swallowed by them. The rolling mass of multiplying parasprites poured over Fluttershy and rumbled toward the remaining four ponies. Twilight could only teleport out of the way and watch as the others were swept up by the buzzing bug-like creatures. In an instant her view of them was blocked off entirely by the parasprites surrounding them.

And the parasprites began to speak. "Fluttershy—"

"Rainbow Dash—"

"Rarity—"

"Pinkie Pie—"

"Applejack—"

"It’s me—"

"Angel—"

"Fluttershy—"

"Sweetie Belle—"

"Twilight—"

"Apple Bloom—"

"And I want you to know—"

"You’re weak—"

"Stupid—"

"A terrible sister—"

"Contemptible—"

"Gullible—"

“Don’t listen!” Twilight shouted. “They’re lying! It’s the parasprites talking!”

"If I’m a parasprite, how could I know—"

"You’re scared to fly—"

"Failed every test, and you were trying—"

"Didn’t eat—"

"Lonely—"

"Losing money—"

Twilight screamed. “STOP!”

She summoned more magic than she knew she had and teleported into the mass of parasprites. Her magic flung them outward, or at least that’s what she intended. They were heavy, tens of thousands of parasprites—Twilight couldn’t imagine how densely packed they must have been—and they were still talking.

“Girls!” Twilight gasped.

The other ponies didn’t respond. They all faced different directions, all turned away from her, all shouting, arguing, crying before the parasprite horde. Only then did Twilight notice how the parasprites were organized into the likenesses of different ponies even distorted by Twilight's magical push. She saw herself and the others, and a dozen other faces she didn’t recognize.

"Girls!" Twilight tried again. "We have to—"

The oxygen vanished from Twilight’s lungs. Pain took its place. Her magic collapsed and the glow from her horn faded as she tumbled over the dirt. She barely had time to register Applejack’s hoof drawing back in before the parasprites swooped down and surrounded them once more.

For a few panicked seconds all Twilight could think about was the fact that she couldn’t breathe, and when she finally managed to suck in a breath, all she could think about was how much it hurt. At least one rib was fractured, maybe two.

Right...too many lies breaks down social cohesion.

Twilight tried not to move. It hurt, but she readied her horn. The parasprites had beaten her, beaten all of them. Her magic was countered, her words drowned out amidst the torrent of lies and, even more destructively, truths. She should have listened to Princess Celestia and fled immediately. Now the fate of Equestria hung in the balance. She wracked her mind for spells she could use.

Something tickled her forehead. She shook her head, and a parasprite floated down in front of her.

No….

It multiplied. And again. Hundreds, then thousands of them. Green, blue, purple, white, gold and orange, and they began to take shape….

“Hello, Twilight Sparkle,” said Princess Celestia.

Even though she knew it was only the parasprites, hearing the princess’s voice warmed her heart and calmed her pain. If the parasprites thought they could break her by showing her the one person she loved and trusted above all, they were as stupid as they looked.

“I’m so sorry,” Princess Celestia said. “I never meant for this to happen.”

Twilight knew it was a lie; she also knew it was the voice of her princess. “I know. It’s okay.”

“I meant for you to die slowly,” Princess Celestia sighed. “Who knew that you would be so stupid as to challenge a parasprite head-on?”

“I should have run,” Twilight said. “I know that. My stupidity cost us everything.”

“Not everything,” Princess Celestia said. “Watching you die like this is amusing in its own way. As a student you were always lacking, but as a victim you’re quite delightful.”

“Talking won’t kill me.”

“No, you will. See that spear that stone econopony is carrying? It’s quite sharp, and you still have magic to teleport. Don’t worry, your friends will join you soon. A spit of ponies for the forest to feast on. Droll, don't you think?”

“If you think I’ll kill myself....“

“I know you will.” Princess Celestia’s voice was soft and warm. "Since it is my last request of you as your princess."

“You are cruel,” Twilight said, “but my princess is not, and you are not her.”

“But I am cruel.” A blue pony with a silver mane formed beside Princess Celestia.

Irrational anger filled Twilight, an even more effective cure for the pain in her ribs than the loving embrace of Princess Celestia. She pushed herself to her knees. “Trixie!”

“And I thought you’d die from boring yourself to death,” Trixie smirked. “But dying out of sheer stupidity? You never fail to embarrass.”

“Trixie was my best and favorite student,” Princess Celestia said. “Never you.”

Twilight laughed. “I know that isn’t true.”

“Twilight!” Princess Celestia’s voice snapped exactly like it did whenever Twilight made a critical mistake. It was so familiar and real she couldn’t help but freeze and backtrack, looking for her error before she disappointed her princess even more. “You know I never thought much of your attempts at adding to economic knowledge.”

“Hard to keep up with a pony who’s been doing it for a thousand years,” Twilight whispered.

Trixie sneered. “Why do you think you lost here? We’ve been doing this forever. Making ponies kill themselves isn’t even the best part, not when you can get them to turn on each other. Want to watch your friends kill each other? Or do you want to kill them yourself?”

“Not happening.”

“Twilight, try to keep up.” Princess Celestia’s disappointment was heavy. “We can read your mind. You will break in exactly the way we want, when we want. Do you understand?”

“Yes.”

“Show me,” Princess Celestia ordered. “Repeat the lesson in your words.”

It was an old practice between them. “You knew everything once you touched my head, all the levers to pull, every strength and weakness, and you’ve been practicing for so long you know exactly how to manipulate them. My brain is putty in your hoofs.”

“How does it end?”

“With my death.”

“Good.” Princess Celestia sounded genuinely pleased. Even paralyzed with fear and buzzing with pain and hatred, there was nothing that made Twilight happier than her princess’s approval.

“Always a suck-up,” Trixie said. “That’s why no pony likes you. That, and your hair. And face. And…actually, what is there to like about you? Maybe if you knew the answer to that question, you’d be willing to talk to that cute blue-maned stallion instead of just stalking him.”

Twilight glared at Trixie. “Who?”

“Oh, but don’t pretend you don’t understand, stupid, I know everything. I even know that circuitous route you take through the courtyard three times a day just so you can see him standing guard. Don’t think he doesn’t notice you. Want to know what he thinks about you? Nothing. Want to know what he would think about you if you ever had the courage to talk to him?” Trixie giggled. “But I think you already know the answer to that question or you would have found the courage by now, wouldn’t you?”

“Trixie,” Twilight said, “even when you weren’t a parasprite, I never believed a word you said.”

“But you believe me,” Princess Celestia said. “My faithful student, so eager, so ready to please, so unimaginative, so limited. Why do you think I sent you away to the NGDP Targeting Festival in Ponyville? Most plausible hypothesis.”

The pain in her side throbbed. “Knew Nightmare Moon was coming,” Twilight gasped.  “Wanted to protect me.”

“Be serious.”

“Don’t know.”

“It’s simple. I can’t stand the way you spend every festival following me around like a dog. ‘Princess, oh Princess,’” now Princess Celestia’s voice was a cruel mockery of Twilight's, “‘Can we study more general equilibrium theory together? Princess, I learned a new magic spell, want to see? Princess, who is that pony? How about that one? Oh, Princess, Princess, Princess!’”

“I’ll list every bad thing you’ve ever done,” Trixie said. “Every moment of your life that brings you shame. You ate all the sugar out of the bowl, but your parents blamed your brother and you let them. You did this twice, actually, and the second time was worse because you knew he would be blamed for it. Everypony made fun of Nook for the way she talked, and you laughed with them. You spat out the food at the school in front of the very ponies who cooked it and said it tasted terrible.”

“Shut up,” Twilight trembled.

“Want me to skip ahead? Oh, I know just the thing. Since Princess Celestia is here, let’s tell her about what you do at night with that dust-covered algebra book—“

“Shut up!”

“Twilight,” Princess Celestia said. “I already know. Every shameful, embarrassing, disgusting thing you’ve ever done, I have always known and I have always loathed you for it. It can end on that spear anytime you want. Look at me, Twilight. I love you.”

Twilight shut her eyes. A dozen pairs of legs peeled them open.

“Don’t turn away,” Princess Celestia said gently. Her voice was forgiving and kind. “I love you, Twilight Sparkle, like a mother loves her daughter. I don't want to hurt you. I want your pain to end. I want you to finally make me proud. Show me how much your teleportation spell has improved. Do it! Do it, and let the last thing you hear be your loving princess telling you how much she despises you.”

Peals of high-pitched laughter burst like audible lightning from behind the princess and Trixie’s forms. Panic seized Twilight. Nightmare Moon had come.

But it was not Nightmare Moon who swept the parasprites away with her tail. It was Rarity.

“Come now, Twilight, they’re only bugs,” she said.

Twilight couldn’t believe her eyes. “Rarity?”

“Ponies usually are stunned to see me,” Rarity said. “Admittedly, not for the reasons you are.”

Twilight lowered her head. “I don’t know what to think.”

“Nonsense!” Rarity said. “You’re an econopony! Thinking is what you do. If you don’t have that, what are you?”

“Not much.”

“Exactly,” Rarity said. Twilight looked up sharply.

Rarity shook her head. “That was not me.”

“Shut up, Rarity!” Twilight snapped. “You don’t need parasprites to say nasty things about people.”

Rarity rolled her eyes. “Boring.”

“You ugly pony,” she added. “Do you have any idea how hard it was to keep from laughing when you stepped inside my shop?”

“You are beautiful,” Rarity said. “I normally can’t resist giving makeovers to first-timers, but the true you always shines through.”

“A lying coward.”

“The bravest pony I ever met.”

“Who let Applejack sacrifice herself to the Cerberus.”

“Who was courageous enough to trust her friend, and whose knowledge let us pass through.”

“Whose light failed in the maze of thorns.”

“Who followed first after Pinkie Pie, whose light restored itself in the blackest darkness.”

The second voice, the other Rarity, was splitting apart, becoming less Rarity and more its components. It began to fade. “Lost to the parasprites….”

“No,” Rarity said simply.

“Who…disappointed…her princess….”

“Princess Celestia relied on you to manage the NGDP Targeting Festival,” Rarity said. “She hid you from Nightmare Moon and trusted you to gather the Elements of Equilibrium and protect Equestria. I have never met the princess, Twilight, but I cannot understand how you would think that she feels anything but love and pride for you.”

Twilight craned her ears. No voice answered Rarity.

“They’re gone,” Rarity said. “Twilight, you can stand now.”

Twilight wiped her eyes. “Ow!”

“Twilight!” Applejack's voice called. Twilight looked up in surprise as Applejack raced over. “I’m so sorry, something funny was going on in my head, I reckon I must’ve—“

“It’s fine.” Twilight winced as Applejack helped her up. She leaned on the strong Earth Pony gratefully.

The ponies were all free, the parasprites gone, though the memories remained, etched on Applejack’s apologetic face and Rarity’s proud one, Fluttershy with Rainbow Dash’s head tucked under her wing and Pinkie Pie frowning like she was puzzling something out.

“What happened?” Twilight asked, bewildered. “How did you defeat the parasprites?”

"It was all Rarity," Applejack said. "She started talking like…like the parasprites except not evil. Some real cutting stuff, and she laughed like…like a witch except more evil. She tossed her hair real pretty, you should have seen it—"

“I have,” Twilight smiled.

“It shut them up quicker than hoof on a rattlesnake. Started…de-multiplying.”

“Dividing.”

“Ain’t that what they were doing before?”

Twilight frowned. “They were dividing, which caused them to multiply…uh, I’m going to have to think about this one.”

“Rarity said nice things too,” Fluttershy said. “Nicer than the parasprites could be mean.”

Twilight looked at Rarity, who beamed. “The answer to lies and deceit is sincere kindness, as much of it as possible.”

“But Parasprites are one of the most dangerous magical species in the world,” Twilight said. “They’ve had thousands of years to practice destroying people with falsehoods and cruelty!”

“And?” Rarity was unimpressed. “I went to high school.”

Pinkie Pie pointed a hoof. “It’s still there!”

Twilight gasped. Behind Rarity the single blue parasprite hovered.

“Hurt…ponies,” it said. Twilight strained to hear it.

“Some, yes,” Rarity said. She stepped forward. The parasprite shrunk back. “I can name them all before you can. But the difference between you and me, you rude little thing, is that I grew out of it. You never will.”

“Hunted…many ponies…how?”

“How?” Rarity laughed like the whine of a metal blade. “You chose the wrong ponies and paid the price. À bon cheval, non? Everything you said about my friends was utterly foolish.”

“Read…minds.”

“But it takes a true friend to read the heart,” Rarity said. “And you thought you tear us apart? Ânerie! No offense, Fluttershy.”

“None taken.”

“You see,” Rarity said, “Fluttershy, who you said is weak, tames bears. Rainbow Dash, who you said is stupid, makes mockeries of millionaires. Pinkie Pie, who you said is lonely, is the most beloved pony in Ponyville. Applejack, who you said is irresponsible, works from sunup to sundown gathering apples and running her family’s business. Twilight Sparkle, whom you tried to destroy in a most base and cowardly fashion, is the most brilliant econopony in Equestria, and it is far too important that her head be full of facts and figures for her to listen to any of your lies!"

“And me.” Rarity smiled. It was the smile of a shark. “You tried to use Sweetie Belle against me? Sweetie Belle is cute. I am not cute.

“Begone, foul creature, and trouble ponies nevermore. If you’re lucky, I shan’t say anything to my friends at the spa next week about your unbelievable tackiosity.”

The blue parasprite hesitated, floating in midair, and then it turned and fled past the thorns and into the shadows.

Rarity exhaled. “Au revoir. Not.”

“Let me at it!” Rainbow Dash shoved Fluttershy away and flew toward the impenetrable hedge of wooden teeth the parasprite had disappeared into. “Let me through!” She tried to push her way through, was repelled, and flew forward again, paying no regard to the blood that dripped from her legs and head.

“Stop it!” Fluttershy cried. “You’re hurting yourself!”

Twilight concentrated. A magical glow surrounded Rainbow Dash and pulled her back.

“Let me go!” Rainbow Dash screamed. Fresh tears poured over worn tracks down her cheeks. “Don’t hold me down!”

Twilight dropped her, shocked. “I just didn’t want you to hurt yourself!”

Rainbow Dash burst into the air and vanished. A rainbow trail marked her path to the other side of the clearing and beyond. Next Chapter: Rainbow Dash's Test: Optimization Estimated time remaining: 57 Minutes