"What I'm about to show you is...secret," Rainbow Dash said solemnly. "It's important that you don't tell anypony."
Fluttershy said softly, "Nopony at all. Don't even talk about it to other pegasi, unless you know for sure that they already know the secret."
Scootaloo grimaced. "What could be so important to keep secret? Oh my galoshes. Is this like those stories I heard from Diamond Tiara and Silver Spoon? They said rainbow color comes from pegasus foals who can't fly! The secret Pegasus Perfection Patrol foalnaps them, and grinds them up to make rainbow juice!"
Rainbow laughed. "Why would you ever believe those two mare's nests? They wouldn't know any more about pegasus secrets than a...wait. 'Than a tortoise would know about flying' is an old saying that does NOT work here."
Fluttershy snorted delicately. "Those two would know a lot less about pegasus secrets than they would know about being nice."
"Yeah!" Rainbow Dash said. "That."
Scootaloo pawed the cloudtop with one hoof, and looked around at Cloudsdale. "I'm sure you two are right. But what IS this secret?"
"Well..." Fluttershy said, "do you remember how I showed you that OTHER secret, and made you promise not to tell anypony?"
"Sure," Scootaloo agreed. "And I even understood why you wanted it to stay secret, how you pay for your animal sanctuary by...well, by making vanilla flavor extract that doesn't have to come all the way from Mareagascar." Scootaloo nodded thoughfully. "But even if somepony else found out the secret, I don't know if anypony other than you even COULD get the beavers to help them--"
"Hush!" Fluttershy said. "The walls have ears!"
Scootaloo looked at the nearby Cloudsdale Corn Palace, which was built entirely from lifelike replicas of ears of corn. "You don't REALLY think--"
"Scootaloo, Fluttershy made you promise for a reason. So don't go around giving out hints, even by accident."
Fluttershy frowned. "Maybe we shouldn't let Scootaloo see this. Maybe she isn't old enough to understand how serious it is."
"Awww!" Scootaloo wailed. "I'm so sorry! I'll keep your sanctuary thing secret, really I will! I'll do better! I promise I will!"
Rainbow said, "We DID bring Scootaloo all the way to Cloudsdale. It would be a shame to skip the main attraction."
Fluttershy's eyes narrowed. "Don't make excuses."
"Awwwww!" Rainbow Dash said in a silly, squeaky voice, imitating a wheedling little filly. "I do a good job of keeping my mouth shut. And Scootaloo admires me SO MUCH. So Scootaloo will do a good job of doing like I do."
Fluttershy sighed. "Fine. I GUESS we can go on the tour. But Scootaloo, if you ever break the code of silence, you aren't a real pegasus anymore. You won't be welcome at my home, or the animal sanctuary, and Rainbow Dash would have to ignore you and pretend you don't exist."
Scootaloo gasped. "I sure wouldn't want that to happen. That would be like losing my favorite sister. It would be EXACTLY like losing my favorite sister."
"See!" Rainbow said. "Scootaloo understands. So let's go on the tour."
Fluttershy nodded. "As long as you BOTH understand how serious this is."
Rainbow said, "But I've already gone on the tour three times! I even worked in quality control one summer."
"I know," Fluttershy said softly. "But you can't be too careful about these things."
***
In a changing room, the three pegasi put on waterproof lab coats, hard hats, goggles, and face shields.
Scootaloo looked at all the protective equipment, shaking her head. "Are you two sure this is really safe? I've done chemistry labs at school where we didn't have to dress up so much."
Rainbow said, "It's better to be protected. At some stages of the process...you really don't want to get that stuff all over yourself, or in your face. But just in case, there ARE emergency showers to wash yourself off."
Fluttershy asked, "Does anypony need to go to the little mares' room?"
Scootaloo said, "Why didn't you ask before we got all dressed up?"
"Sorry. I guess I just forgot."
"I really want to see the tour!" Scootaloo said. "I can go to the little mares' room afterwards. I can hold it."
"You can hold it, no matter what?" Fluttershy asked.
Scootaloo's eyebrows quirked. "What are you two going to show me, anyway? What are you going to DO?"
"You'll find out," Fluttershy said. "I promise."
Rainbow led the other two ponies out of the changing room, and to the next part of the tour.
***
Vats of brightly colored liquid steamed and churned. Large stirring machines ensured the liquids were mixed evenly. Banks of giant thermometers showed that every tank of liquid reached a temperature of at least 160 degrees Marenheit.
"I guess we could switch to Celsius," Rainbow confided, "but Marenheit numbers are higher, which looks hotter, which makes it seem cooler."
"Huh?" Scootaloo asked.
Fluttershy said, "The important thing is, all of the liquid in each of these vats is heated hot enough for long enough, to kill any germs. The liquid should already be sterile, but it's important to make absolutely sure, just in case."
Rainbow nodded. "It's very important not to have any rainbow germs. Ponies would get SO UPSET if we did."
Fluttershy explained, "Back in the Mareddle ages, before ponies properly understood these things, some batches of rainbow juice weren't properly treated, and...bad things happened. That caused the Maredieval Gray Plague. We work hard to make sure it will never happen again."
Rainbow said, "Scootaloo, this is very important. If you EVER see a rainbow that has a gray stripe, or even just a LITTLE bit of gray, you have to find an adult pegasus IMMEDIATELY and tell them what you saw. Swear it by your wings."
"By your wings," Fluttershy repeated.
Fluttershy raised her wings, and demonstrated how to swear the secret oath. Rainbow swore it next. Finally Scootaloo imitated the two older pegasi.
"Ok," Scootaloo said, "I'll remember to do that. Now what's the next part of the tour?"
"Well..." Rainbow said, "are you SURE you don't have to use the little fillies' room?"
"What is it with you two, always wanting to go to the bathroom today?" Scootaloo asked. Her facial expression changed. "Oh my Celestia! You two aren't some kind of pee play weirdos, are you?"
Rainbow laughed. "I would NEVER want to play with pegasus pee. Pegasus pee is serious business."
Fluttershy agreed, "It isn't something to be used for games."
Rainbow said, "Well, now to the next part of the tour."
***
Scootaloo said, "Isn't it WEIRD, watching all these other mares sitting on the toilet? And why does the Factory have all these special, different toilets anyway? Doesn't it all go the same place?"
Fluttershy giggled. "You would think so, wouldn't you?"
Rainbow enthused, "But it's awesome that you think it all goes to the same place. That means the secret plan really is secret!"
A mare put down her newspaper, got off one of the toilets, and went to the sink to wash up. The next mare in line trotted over to take her turn.
"Didn't you ever wonder," Rainbow asked, "why ever since you were a tiny foal, your family taught you NEVER to let another pony watch you use the toilet?"
"EVERYPONY knows not to let anypony see you use the toilet!" Scootaloo seemed infuriated. "What is WRONG with you mares?"
Fluttershy said, "Toilet privacy is part of an ancient pegasus conspiracy. We convinced EVERYPONY that using the bathroom is a private thing, so nopony would even suspect."
"Suspect WHAT?"
"That we pegasi are different." Rainbow waved a wing at a transparent section in some of the tubing. "Watch! That mare is about to flush."
The mare flushed. Whooshes and other noises traveled through the network of pipes.
"There it goes now!" Rainbow said. A transparent tube turned from clear to green as it filled with liquid, and back to colorless as the flush traveled onwards.
"Ok," Scootaloo said. "You say you're not pee weirdos. But I guess you REALLY like to look at pony pee."
"It's not some weird fetish!" Rainbow insisted. "It's just quality control. It's important!"
Scootaloo took a deep breath. "Let me think about what you've been showing me. The Factory has huge vats of brightly colored liquid. The Factory treats the vats to make sure there aren't any germs."
"Right!" Rainbow agreed.
"And the Factory thinks mare pee is very, very important."
"Still right!" Rainbow nodded. "You're a smart litle filly."
"So when you do your sonic rainboom, and it makes a giant rainbow trail and the rainbow spreads out through the sky...EEWWW! Eeewww eewwww yuck yuck gross!"
Fluttershy whispered, "She figured it out. What rainbows are made of."
"It's not as bad as it sounds, Scoots! I get checked by a doctor every month, to make sure I don't have any urinary infections, so it really will be sterile! And the superspeed and the boom boil my pee into colored steam, so even if there were any germs, it would kill them...we think. We're pretty sure it works that way."
"I'm never going outdoors again."
"Don't feel that way! It's ok. Really it is."
"Get your SKY-peeing hoof off my shoulder! I never want to hug you again." Scootaloo shuddered, backing away from her adopted big sister. "You pee sprayer. I don't fly around peeing all over YOU."
"Scootaloo," Rainbow said, trying to sound reassuring. Rainbow whispered, "Did you ever wonder, that one time you slept over and you peed the bed, why I didn't get upset? Like even a little bit?"
Scootaloo whispered back, "I didn't MEAN to do that. You KNOW I didn't mean to do it. But now I find out you fly all over Equestria, peeing up a storm--"
Shocked, Rainbow whispered, "Who TOLD her about STORMS? She isn't supposed to find out how pee is used to energize lightning bolts until NEXT year."
Fluttershy shrugged. "Lucky guess? She was talking about chemistry class earlier. Maybe she found out what saltpeter is made from, and how it's used in gunpowder--"
Scootaloo shook her head. "I'm going to tell everypony. Everypony is going to know what TERRIBLE things you're doing." Scootaloo ran away, trying to find the way out of the Factory.
Rainbow Dash and Fluttershy ran after her.
***
Rainbow stood in the doorway of Scootaloo's home. "Aunt Holliday? Auntie Lofty? I think we should sit down."
Fluttershy suggested, "Let's go into the living room."
When everypony was sitting down, Rainbow spoke. "When we went to tour the sights in Cloudsdale...well, we went to get some ice cream. I just thought Cloud's Edge Park would be scenic. I had no idea..." Rainbow shed sincere tears.
Fluttershy nodded, dabbing at her own eyes. "It was so unfair! Such a sweet little filly! She meant the best for everypony! But she didn't understand how close to the edge she was." Fluttershy bawled and wailed.
Holliday and Lofty stared in shock. Lofty was the first to understand. It might have helped that she was a pegasus herself. "So...the tour..."
Fluttershy sniffled. She said softly, "It didn't go well at all. I had no idea. I thought she would be more careful."
Holliday said, "I can't believe YOU weren't more careful! Just a little filly...and you KNEW she couldn't fly. How could you...why..." Holliday stood up and slapped Rainbow across the face.
"I suppose I deserve that," Rainbow said. "I'll just be going now. I can cry just as well at home as I can here." Rainbow stood up to leave.
Fluttershy insisted, "We really didn't mean for anything bad to happen. Rainbow thought..." Fluttershy's shoulders heaved with quiet sobs. "You don't know, how much Rainbow loved our little Scoots. This hurts Rainbow as much as it does you."
"I can't BELIEVE," Holliday said angrily.
Fluttershy said, "I am SO sorry." She sobbed again.
Rainbow ran out the front door, leaving it open behind her.
***
On the bottom of a small cloud beneath Cloudsdale, a pegasus filly had her forelegs hooked into and buried in the cloudstuff.
"I can't believe they would DO that," Scootaloo said to herself. "All those pegasi who caught up with us at the ice cream shop, trying to throw me off the edge of the cloud to keep their stupid icky gross secret. Rainbow and Fluttershy pleading for my life, and everypony else not even caring what they had to say."
Scootaloo knew she had been very lucky, to grab onto a bit of cloud beneath Cloudsdale, and swing herself underneath it to hide from the ponies who had thrown her over the Cloudsdale Edge.
Those ponies had underestimated her. If a pegasus can't even fly, what good could that little failure possibly be? How could a reject like that possibly survive being thrown off the edge? They'd thought Scootaloo was completely helpless in the sky. But those arrogant pegasi were wrong.
"I'm not just ANY reject," Scootaloo whispered angrily. "I'm the BEST reject."
Scootaloo tightened her stomach muscles, to lift her hindquarters closer to the cloud. All the exercise she'd gotten with the other Cutie Mark Crusaders as they ran all over Ponyville and tried out every way they could think of to maybe get a cutie mark? That exercise was paying off.
Scootaloo's hind legs dug into the cloud, carving out the mouth of a tunnel. She thought if she could dig deeply enough, she could crawl up inside the cloud to hide. She could dig peepholes to see out, and watch all around, waiting for an opportunity to get farther away from Cloudsdale.
"No wonder my parents ran away to bucking Shire Lanka," she said. "I think they had the right idea."
An hour later, through one of her peepholes, Scootaloo saw a large airship flying towards her. If she could leap down onto it, she would be saved.
