Luna jerked awake, pulling from the dream-world at the same time as a mare in Canterlot was screaming. "I am sorry Twilight Sparkle, but you needed to know, and I had few choices in how to tell you."
Climbing from the slightly undersized bed in the tree-house, Luna climbed down to the library itself. The place was impeccably kept, the books in perfect order, except for one spot. Luna stood over where the Elements of Harmony should be kept. She lifted her hoof and gently rubbed the shelf. "No dust." The book to the left of the empty spot fell into the gap. "Elemental Disturbances and Time Anomalies." Luna read the title and felt a cold shiver of fear through her. "Twilight wouldn't have left a gap like this—for these books to fall into—without…" Luna lifted down two bookends with her magic, and fit them in the gap. It looked like they had seen this duty before.
Looking out the little window of the library, Luna confirmed what her senses told her. "I need to be fast, I need to find this changeling quickly." Laying down comfortably, she reached back into the dream-world and raising her horn, drew everypony in the town into it. She plucked up ponies as far out as she could and, while holding them in the dream, fought more to keep the Tantabus from being revealed. "Ponies of Ponyville! Look around, mark who you see here."
"What is going on?" Sweetie Belle trotted over to Apple Bloom, smiling at her friend. "Where's-"
Luna cut off what the filly was about to ask. "And mark more who you do not. I need to know what ponies are missing that should be here." She gazed around, pinning ponies who looked nervous.
"Excuse me, Your Highness." Rarity yawned despite not feeling tired, after all it was still nighttime. "I presume there is a good reason for this?" She made sure to cover her mouth lest another yawn break free.
"Rarity, the Elements of Harmony were taken from the library some time after everypony left for the wedding. Either a pony or a changeling in this very town moved them. Changelings… most changelings, cannot be pulled into a shared dream like this."
Nearby, Derpy was panicking so much her wings were twitching. She had overheard Luna's conversation with Rarity and knew a pony who was missing. Dancing from hoof to hoof, she tried to piece together all the reasons for Bulk not to be in the dream. "Early morning training? Maybe he got woken up by a muscle cramp? Oh Bulk…"
"Derpy, what's wrong?" Apple Bloom, still waiting for Scootaloo to join them, trotted over to the distraught pegasus. "Are you alright?"
"Bulk…" Derpy couldn't say anymore, she had her eyes screwed up and was almost crying. "Princess Luna said anypony not in the dream is a changeling."
Pieces fell into place and Apple Bloom looked around before ducking under Derpy and carrying her despite the size difference. It was a dream after all.
"Apple Bloom, what are you doing?" Sweetie Belle trotted along beside her laboring friend. "Where are we going?"
"Hiding." Apple Bloom trudged on, able to carry the panicking pegasus with ease. "Okay, here will do. Derpy, are you sure that is what Princess Luna said? That anypony not here is a changeling?"
Derpy nodded mutely. "Bulk Biceps isn't here… why wouldn't he be here?" Tears started again, she couldn't stop them. I like him, I like how into life he is, how much he doesn't care if I am a little off-center now and again! It isn't fair!
Sweetie nodded to the sad pegasus. "And S-" Suddenly Sweetie Belle was tackled, two yellow hooves over her snout and holding it closed.
Apple Bloom heard shouting in the distance, a lot of it. "We have to wake up, whatever way we can. Derpy, come to our tree-house, okay?"
The gray mare had a fraction of a second to nod before a huge yellow hoof connected with her snout, knocking her awake and leaving her rubbing her jaw in the waking world. "Bulk!" She sat up sharply, looking around. Falling out of bed and landing sideways on the floor, Derpy flapped her wing on that side. Suddenly she was struggling for the door and reached it only to find a pony already waiting for her. "Princess Luna?"
"You are a ghost in this town, Derpy Hooves. You travel around and everypony sees you, but nopony notices you. You had access to Twilight's home, you could even have shipped the Elements of Harmony off to Canterlot." Luna clopped a hoof sharply on the ground. "And nopony remembered seeing you in the dream."
Rainbow Dash was the first of Twilight's friends to reach the confrontation and without hesitation followed her heart. "Princess!" Dash crashed into the ground between Luna and Derpy. "She might have just been having a bad night's sleep. How do we work out if she is a changeling or not?"
"Hi!" Pinkie Pie pronked up. "I hear somepony might be a naughty-buggy!" Pinkie produced a muffin from her mane. "Do I need to plan a changeling-coming-out party?" She practically beamed at the idea of having a reason to throw a party.
"If she is a changeling, the real Derpy will be gone, trapped in their hive." Luna was on edge, she needed Pinkie to reveal the truth and she needed it fast. "Pinkie Pie, please find out."
Derpy was almost on her belly behind Rainbow Dash. She pulled her forehooves over her face to hide from whatever fate was coming.
"Hey, Derps, it is you isn't it?" Rainbow Dash waited for the trembling pegasus to nod. "Cool, I thought so. Look, just sit up and look into Pinkie's eyes, okay? I'll keep the Princess from getting at you." I really hope I don't have to fight a princess...
Pinkie offered Derpy the muffin she had. "A pony so sad she doesn't want one of my triple-butter muffins? It is still warm-" Pinkie didn't get any further, Derpy was in front of her and cramming the muffin into her snout. "Well now I know you are Derpy, but I guess we have to put on a show for 'Princess Accusey-Pants.' "
Derpy munched on the muffin as Pinkie squared up and looked into her eyes.
"I can't tell." Pinkie blinked a few times and tried again. There was not only no sensation of her Pinkie Sense telling her she wasn't a changeling, but it simply didn't work at all. "Oh, silly, it is her eyes. Derpy, can you look right at me?"
Derpy blinked a few times before realizing what her friend wanted. Fighting the nature of her eyes, she got one and then the other looking forward at the same time. "Ow, this feels odd…"
"Gotcha!" Pinkie pulled a second muffin out and passed it to the mare. "Now, if you excuse me…" she turned and looked up at Princess Luna. "STOP BULLYING MY FRIENDS!"
~~~~~+++++~~~~~
"Twilight, I have already started a list of everything you need to do to-" Spike halted, scroll almost dropping from his fingers. "Twilight? What's wrong?" He was a little surprised to see a changeling march into the room where Twilight was still tucked into bed, a tray of food held aloft in their magic.
"Just had a rough night, Spike." Twilight didn't want to freak her Number One Assistant out, even if she felt like freaking out herself. "Oh, this is Soft Clack. Thanks."
Soft set down her tray of pancakes and syrup before the pony. "Your favorite?" She didn't need the unicorn to answer, Soft could taste that if not favorite, this was certainly a food Twilight Sparkle loved a lot.
"Mmm!" Twilight was grinning around the mouthful of pancake she stuffed in her snout.
"You may have just made a friend for life. Can you keep producing those pancakes every day?" Spike tossed the writing things up on the bed, then followed them himself. "So, I was talking with Braced, he said our Queen wishes a morning of celebration for Shining and Cadance, and to welcome her own rise."
Twilight stopped munching, her brain halting from its present occupation of "food intake controller" and spreading out to the more world-relevant tasks of examining speech and extrapolating ideas. "Clever. Everypony is happy they got married, rub some of that off on herself. Some will see it for what it is, but enough won't." She nibbled her next fork-load of pancake. "How do these pods work?"
Soft Clack was caught between conversations and topics. She blinked her big blue eyes a few times to process and mentally shunt the old info around and get what was needed ready. "We don't have any, Queen Chrysalis forbids them."
"But if I asked her, could you make one? What happens to the pony in them? Does it hurt? What would-" Twilight halted as her fork deposited another mouthful of pancake in her open mouth. It was held by a purple dragon claw. "Hrmmff!"
"You have to understand, Twilight thinks she is a changeling of knowledge, able to feed off it alone." Spike was already loading another fork-load before Twilight could even finish the first. He flashed an impish grin at Soft. "So her number one assistant frequently needs to remind her that once breakfast, lunch, or sometimes even dinner; is finished, then science can happen."
Soft was giggling so much she snorted and tried to cover her snout with a hoof, which just meant she was snorting through one of the holes in it. She barely got herself under control when Spike fed Twilight the next mouthful, he then leaned over the side of the bed to see the "scary" changeling infiltrator rolling on the floor laughing.
"Huh. Well, looks like the invasion will have to be called off, I figured out how to defeat all the changelings." Spike sat back from the edge. "Science comes after food, you promise?" He looked at Twilight, his eyes serious.
Knowing she wouldn't have the heart to fight Spike's efforts, Twilight reluctantly nodded and agreed. She took the fork from him, glad to get control of her breakfast back. "I am supposed to be a princess now, don't I get to say what I do?"
"Actually," Soft had managed to recover from her giggle-fit, "you haven't been officially crowned, and even then… have you seen how busy mom gets?"
Twilight blinked at the changeling reverting to "mom" instead of Chrysalis' full title. It is really sweet... "So I don't get to start my own school and spend my days studying?" Something poked Twilight mentally, she sat a little straighter. "Are my friends okay?"
"Princess Luna wouldn't hurt them." Spike suddenly felt like a very small dragon, the problems of the world of Equestria massive compared to him. "Maybe we should send them a letter? Or go visit?"
"We could certainly ask the Queen." Soft smiled, almost chittering in happiness at the amazing taste of love Twilight had just put out. "I think I would really like to be there when you meet your friends again." Over-excitement borne of the heady love she had just fed on made Soft blush a bright green and then chirp when she realized what she said. "Oh, I mean-"
"What's the matter, Soft?" Twilight looked at the drone as she had another mouthful, hearing Soft chirp a few more times in sudden worry.
"I was feeding off you." It wasn't like I could help it, she tasted so good. Queen Chrysalis is going to squish me… Soft lowered her head but was stopped by something glowy at her chin. Tilting her head back up, she saw Twilight's horn was lit.
"For one thing, it is the law to let you feed off me. But more importantly, you looked really happy when you did, and it doesn't hurt." Twilight set her food aside and scooted to the edge of the bed to reach out and pull the surprised Soft into a hug. "Feed off me all you like, but make sure you let me know how happy it makes you, okay?"
Soft blinked at the question, not fully realizing what Twilight was asking. "You… you really mean that?"
Twilight nodded. "If just feeding a little off me can make you so happy, then I consider it worth the price… uh, is there a price?"
"No science until after breakfast!" Spike bopped both unicorn and changeling on the nose in the nicest way possible. He couldn't stop himself giggling, though, and it caught with both Twilight and Soft. Apparently laughter was always on the menu.