Scientific Analysis

by Samey90

First published

The Doctor is interested in some peculiar properties of Derpy's butt. Research ensues.

It occured to the Doctor a long time ago that his faithful assistant's behind has some rather interesting capacities. Bending reality, changing entropy... There was a lot of data suggesting something deeper. Now, the Doctor finally has a chance to study Derpy's butt in the controlled laboratory environment. And Derpy doesn't mind a little science either...

A collaboration with Bootsy Slickmane who also drew the coverart.

Reading by Yamazaki
🇺🇦Russian translation🇺🇦 by FoxcubRandy and ColdSky
Warning: science, property damage, anal

An In-Depth Research

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“Hi Doc,” said Derpy with a smile. “You wanted to see me?”

The Doctor shot a smile back and stepped aside, pushing open the door to let her pass. “Yes, yes. Come inside, my dear.” The door swung shut behind her, and he ushered her down to his laboratory.

She went down the stairs of his lab in a way she always did – with some natural elegance, which many found surprising. The Doctor stared at her for a while before deciding that it’d be safer to focus on something else. He looked around his lab in panic and his eyes rested on a nearby clock. The pendulum was moving up and down in swift motions. It wasn’t, however, the only thing that was up there.

“Oh, good, my toast is done.” The Doctor trotted to a large, steam-powered toaster. Or rather, an illegitimate offspring of a toaster, hairdryer, and a parade float some kid had crashed during the last Summer Harvest Parade.

Derpy walked to the nearest table and sat on it, putting one of her hind legs over another. Her gaze drifted over the various tools, machines, and half-baked inventions littering the lab. “So, what did you need my help with?”

The Doctor dropped the toast from his mouth and onto a plate. “Ah, yes. I’ve been conducting a series of experiments involving a connection between time, space, and some relative aspects of classical mechanics, such as friction around the black holes...”

“... okay,” Derpy said slowly, eyes locked on the Doctor. “What did you need me for?”

“Well, not so much you as I need a part of you. More specifically, your, well… your butt.”

It was at that precise moment that the table beneath Derpy cracked in half, sending her to the floor with a thunk. “My butt? Why my butt?”

The Doctor put a hoof to his chin for a second. “How do I put this? Your buttocks would seem to be something of a physical anomaly. They create a sort of dimension of heightened entropy around them, causing things to break...”

“Oh, I get it, Doctor!” Derpy exclaimed, swishing her butt around. The Doctor barely had time to catch a couple of precious clocks she knocked off the shelf. “It’s just like when I destroyed the town hall by scratching my butt against the railing?”

“Yes... I must admit that it was an exceptionally powerful manifestation...”

“I had a really big lunch.” Derpy shrugged. “You know, when Rainbow Dash makes chili...”

“I can imagine...” The Doctor shuddered. “The horrors I’ve seen after eating it... Nevermind! Derpy Muffins Hooves, do you agree to do science with me?”

“You bet, Doc!” Derpy nodded enthusiastically, her tail wagging behind her. “What do we do first?”

“Well, I’d need some initial observations... Like, taking measures...” The Doctor pulled a long, flexible tape measure from a seemingly-disorganized pile of tools. “You don’t mind, do you?” he asked, already wrapping the flat strand around her backside and jotting notes on a scrap of paper.

“Interesting...” he muttered to himself. “Interesting...”

“What’s so interesting, doc?” Derpy asked, turning her head to see him.

“It’s like, each of your buttocks is about thirty-five centimetres wide when I measure them individually...”

“I know, I eat a bit too many muffins recently,” Derpy muttered. "But they're just so good! Corn bread, banana nut, and blueberry! By Celestia, the blueberry!"

“But the interesting thing is, when I measure them together, it’s about eighty centimetres...” The Doctor put the tape the other way round. “But when I change the position of the tape, it’s seventy.”

“What does it mean?” Derpy asked. “Apart from the fact that I need to go on a diet?”

“Haysenberg’s uncertainty principle!” the Doctor exclaimed. “I change the outcome by observing it!” His pen flew across the page for a few seconds, and then he dropped both pad and pen. “Alright, phase two. Would you be so kind as to walk across the room for me? I’d like to get some initial observations of the mechanical interactions the rest of your body has with the physical properties of your butt.”

Derpy shrugged once, said, “Okay,” and started walking. Derpy’s smooth, round buttocks slid against one another as she made her way across the lab, almost gliding as though greased with some industrial-grade lubricant. Her tail swished left, then right, then back again with each step she took, like a golden pendulum in some grand clock, only made of hair and not in a clock. Each impact her hind hooves made with the floor sent only the slightest jiggle rippling up her hindquarters.

“Fascinating,” the Doctor breathed, his pen left forgotten on his notepad. Derpy came to a stop at one end of the room, turning to look back at him with a sheepish grin. The Doctor cleared his throat. “Could you do that again, only slower?”

Derpy repeated the process, taking her time with each stride she made. Her hind hooves lifted with a grace unnoticed by most ponies. One might even swear that her tail moved just a bit more than it had during her previous demonstration. After reaching the other side of the room, she again turned her head toward the Doctor, shifting on her hind hooves a little as her tail swung loose behind her.

The Doctor finally shut his open mouth and swallowed, quickly shaking his head and writing a few things on his notepad. “We may be on a way to a great discovery...” he muttered, pulling out a small device.

“This looks funny.” Derpy looked at the device and smiled. “What does it do?”

“Great things, my dear, great things!” The doctor spun a small clepsydra on one of the end of the device. “Don’t worry, it won’t hurt... I just want you to lift your tail a bit.”

Derpy obeyed the command. The Doctor barely managed to touch her butt with the device, when the glass of the clepsydra shattered. Steam came out from the end, causing the Doctor to cough.


The Doctor’s eyes widened. “I’ve never seen such a high entropy before...” He tossed the broken instrument aside. “Do you know what this means?” he asked with a smile.

“Um, no?” Derpy said.

“Me neither! But I simply must know more!”

“But what are we going to do?” Derpy asked. “Your thingy exploded and seems that it won’t work for a while now.”

“Fear not, Derpy!” the Doctor replied. “There are other things we can check!” He turned away, galloping off to a dark corner of the laboratory. He came back with a grunt, pushing a machine as big as an adult manticore out into the center of the room. From its curving, half-moon shaped frame sprang four segmented arms, each tipped with a metal paddle. He slid the machine right up to Derpy, situating her rump right in the middle of the collection of arms.

“W-what is that?” Derpy asked, her ears pinned back against her head. “It looks like a giant spanking machine.”

“Well...” The Doctor blushed. “It is used to measure the relative density of matter, but it certainly has some... other uses.” He took a moment to cough into a hoof before adding, “But don’t worry. It won’t hurt you. Just hold still, my dear.”

Derpy did as instructed, standing as still as she could as the machine hissed, seethed, and whirred to life behind her. Its arms shuddered and shook for a moment before descending toward her. Each limb pressed its flat, metal plate to her butt, two to each cheek. She winced at the cold touch, but remained still. The device beeped after a good ten seconds of contact, and withdrew its paddles. A thin strip of paper slid out from a slot in the machine, and the Doctor pulled it free with a hoof.

The Doctor hummed. “I’m not sure what to make of this.”

Derpy crouched down and slid out from under the machine. “What does it say?”

“It’s all nines, just over and over again.” The Doctor shook his head. “This can’t be...”

“Well,” Derpy smiled, staring into the Doctor’s eyes. “Do you know what they say about space?”

“I know many things they say about space,” the Doctor replied. “Which of them do you have in mind?”

“Like, they try to send many machines there, magical or not, but only a pony can bring accurate results...”

“Oh...” The Doctor backpedalled. “I’ve never considered that before...”

“I guess it should be easy.” Derpy smacked one of her cheeks with her hoof, causing it to bounce slightly. “Well, I don’t know what it means. Doc?”

“Well, this should be easy,” the Doctor said, more to himself than to anypony else. He reached with his hoof, stopping inches from Derpy’s butt. “It’ll definitely be a great moment. A first scientist to examine an ass such peculiar... A pioneer, I’d say. Great whickering stallions! I may be on the verge of one of the greatest discoveries of this century! I’m excited just by thinking about it!”

“I can see it from here,” Derpy muttered. “But why don’t you touch it already?”

“Ahem, right, yes, of course.” His head shook atop his neck, and he brought his gaze back to Derpy’s remarkable ass. His hoof inched ever closer to her flesh, her tail twitching once as he brushed against it. Finally, first contact was made, and his hoof pressed into the soft surface of her right butt cheek.

“A small touch for a pony...” the Doctor muttered. “A great leap for the ponykind...” A shudder ran from his hoof to his foreleg and then through his entire body. He had to grit his teeth to keep them from chattering in their gums. It was almost too much. He was the first stallion to touch a butt so mighty, so mysterious, so firm and yet pliable to the touch. His hoof found itself running circles over her hindquarters as he took in the feel of a butt that defied all he knew about the world. Nothing in his studies had ever prepared him for an ass like this.

“Uh, what’re you doing?” Derpy asked.

The Doctor started, pulling his face from the pillow that was her rump. “Nothing! I was just taking a few… notes.” He wrapped his mouth around a pen and made a few squiggles on his notepad. “Have to record my findings, of course.”

“And what did you find back there?”

“A… Some very fine geometry.”

Derpy tilted her head to one side “Um, thanks?”

“Beyond that, I can’t be sure.” The Doctor put his other forehoof against her butt. “It feels like a normal butt, I think. Though it seems a bit more dense than one might expect.”

“Alright, alright,” said Derpy with a roll of her eyes, “I’ll lay off the chocolate muffins.”

“I fear this may be far more than a dietary issue, my dear Derpy. If only I had some better way…”

The pegasus shuffled her hind hooves a bit. “Well, I guess… I guess you could, um, explore a little deeper?”

“Yes, of course,” the Doctor whispered. “Perhaps it’s not the butt itself, but the space contained within the butt.”

“Yeah,” Derpy replied. “You need to explore the middle part. After all, the most interesting things are usually there, right?”

“Indeed.” The Doctor opened one of the drawers and grabbed a pack of rubber socks. “But, of course, safety first.” He took a sock and put it on. “Now I can boldly go where nopony has gone before.”

“I was hoping for that.” Derpy lifted her tail and bent over slightly. “Let’s do science, Doc...”

The Doctor looked between Derpy’s cheeks and spread them a bit. The tight opening between them twitched slightly upon his approach. The Doctor touched it and rubbed it, causing Derpy to moan.

“Something’s wrong?” the Doctor asked.

“No,” Derpy replied. “Please, continue.”

For a few minutes, the Doctor was examining the rims of Derpy’s anus. Under his hoof, it puckered slightly, encouraging him.

“Interesting,” the Doctor muttered. “This is quite a new experience for me.” He sniffed the air. “What’s that smell?”

“I’m getting a bit wet.” Derpy blushed, rubbing her marehood with her hoof. “You know, it’s kinda close.”

“What do you mean?” The Doctor only had to glance downward to see her hoof rubbing little circles against her glistening slit and get his answer. “Is it supposed to do that?”

Derpy’s juicy double wiggled beneath the Doctor’s hooves as she spread her hind legs a little further. “Um, could you keep going, please?”

“Hmm. No, I don’t think so. I can sense nothing strange, here.” His forehooves dropped to the floor. “This isn’t getting me anywhere.”

“It isn’t?” Derpy pouted. “But…”

The Doctor tapped one of his rubber-socked hooves to his own chin, eyes scanning the ceiling. “Perhaps the source of the phenomenon can’t be seen from here. Perhaps I need to go deeper inside.”

Derpy nodded energetically, her mane flapping against her forehead. “Yeah, you should do that. You should go real deep, Doc.”

“Yes, I think you’re quite right. But, how?” He reared up, holding both hooves up in front of himself. “These hooves aren’t suited for an investigation in such a tight, delicate place.”

“Do you have anything else that might fit?” The mare swung her head around, tossing her mane as she did so. “Maybe something long and—” She stopped dead as the Doctor plucked up what looked like a miniature, chrome-plated cactus with blinking yellow lights dotting its surface. Her eyes shot wide and her tail fell flat against her backside. “Um, maybe something else?”

“Hmm? Like what?”

“Well, from here, it looks like you already have an organic probe ready to go down there.” She gestured with her snout toward his hooves and gave him a crooked smirk.

“What? Where?” The Doctor’s gaze swept across the floor, under his workbenches, and finally down to the rigid shaft of horsecock hanging under his belly. The chrome cactus tumbled from his hoof as his forelegs crossed to cover himself. “Oh, bollocks! How could I have missed that?”

“Why don’t you use that? I think it’ll fit perfectly. And, uh”—Derpy paused for just a second, glancing toward the floor—“it’s got lots of nerves. Perfect for exploration and sensing stuff, right?”

The Doctor uncrossed his legs, looking at his own member as though it were some fascinating alien furball. One of his socked hooves ran down it as he said, “You may be onto something, there. Then again, what if the depths of your butt is where the effects of the phenomenon are the strongest?” He stood up straight, staring at some blank spot on the ceiling. “Is it wise to venture so deep into the unknown with not but my own skin? It is bold, or is it foolish? How much is one such as myself really willing to risk in the name of science?”

He winced suddenly as Derpy’s tail snapped across his face. His eyes turned back toward her, and she raised her tail up to expose her nether regions, giving him a bored expression.

“Right, onward to the unknown, for science! Allons-y!” He hopped up, putting one forehoof against her back and using the other to align his rod behind her.

“Ouch!” Derpy cried when the Doctor’s dick hit her fine ass, barely managing to penetrate it. “This hurts!”

“Oh, sorry.” The Doctor retreated, blushing. “M-maybe we should stop?”

Derpy turned to him. “I don’t think so,” she replied, rubbing her slit idly. She raised her hoof, fur on it matted from the juices. “I guess we just need something slippery for that...”

“I have kerosene,” the Doctor said. “Will it do?”

Derpy facehoofed. “Something that doesn’t start to burn when heated from friction...” She trotted to the chest of drawers in the corner of the Doctor’s laboratory and opened one of the drawers. “Oooh...” Her eyes lit up when she took a small, purple bottle from the drawer. “Where did you get that, doc? It’s exactly the same stuff I keep stealing from Carrot Top...”

“Umm...” The Doctor scratched his mane. “Well, I thought it’d be useful in unjamming rocket parts, since it’s called ‘Space Jam’, but apparently I was mistaken...”

“Don’t worry, doc.” Derpy opened the bottle and poured some of the lubricant on her hoof. “We’ll unjam some big rockets with it today...”

“So, are we going to explore space?” the Doctor asked, staring at Derpy unsurely.

“Yeah,” Derpy replied. “It’s a rather small space, but I guess you’ll fit...” She spread her cheeks and rubbed some lube into her opening. She then gave the bottle to the Doctor who smeared some substance on his dick, positioning herself over Derpy.

Derpy rested her front legs on a work table, spreading her wings. “Grab them at the base,” she said to the Doctor. “That’s what they are for...”

“Okay,” the Doctor replied, staring at Derpy’s butt and making calculations necessary to aim perfectly. “For science?”

“For science!” Derpy exclaimed. She felt the Doctor’s hooves on her back and gritted her teeth as his shaft poked her cheeks. The blunt end of his rod found its mark, and the Doctor pushed forward. For a few seconds, it seemed as though his inner-space probe was making no progress. Derpy let out a held breath, and then her tight ring finally relaxed enough for him to slip inside. It was slow going, with his probe meeting heavy resistance along each inch of its tight, gritty journey into the mysterious void of Derpy’s ass, but the Doctor pressed on into the unknown.

Derpy’s hoof moved to cover her mouth. A short little groan left her lips, and her eyes fell shut. Her teeth clamped down on the edge of her hoof just before the Doctor’s initial exploratory thrust finally halted. “What…” she began, taking the hoof from her mouth, “what are the readings, Doc?”

“It’s hot, tight, a bit grainy, and I have the strangest urge to imitate a piston in a steam engine.” The Doctor stepped sideways ever so slightly, adjusting his angle. “Anything of note on your end?”

“Can we hold off on the piston thing for a little bit, and gather more data first? And not really. It feels really big, though; it doesn’t fit as perfectly as I thought. And it kinda still hurts.” Derpy sent her wet hoof back between her hind legs and went back to rubbing her marehood. A look of calm began to take hold of her face, only for her to wince as she involuntarily clenched around the thick stick inside her.

The Doctor, meanwhile, was scribbling a few notes onto his pad, which he was awkwardly balancing on Derpy’s spine. He dropped his pen. “I’m not sensing anything particularly peculiar inside, I think. I don’t think I can go any further in.” He gave a quick shove of his hips, managing to get another inch of depth and a squeak of out of Derpy. “If the source is any deeper inside, I’m afraid I can’t reach it. Blast, where did I put that pipe snake of mine?”

Derpy bit her lower lip, watching with concern as he looked about the lab. “Maybe you don’t need to go deeper. I think we can try the piston thing, now, if you want.”

“Right-o.” The Doctor pushed his forehooves against her ass, pulling his hips back and sliding his dick almost completely out of her. Derpy stifled a whine as he reversed direction and penetrated her again, going a little faster than the first time. His motions steadily increased in speed, Derpy’s chin hitting the table’s surface upon the third thrust. Her eyes were held shut, and each thrust was accompanied by her own heavy pants. Her hoof kept going against her slippery folds as more fluid seeped out.

It seemed as though each push was easier than the last for the Doctor’s oil-down dipstick, and he soon had little trouble reaming out Derpy’s ass, his wrists wrapped ‘round her wing bases. As the resistance of her ever-loosening pucker lowered, so did Derpy’s body relax against the table. Soon, her labored pants turned to a rhythm of soft moans and hums.

“How are you?” the Doctor asked, going deeper into Derpy’s ass and feeling her muscles loosen. “I can feel some strange sensation...”

“Don’t stop.” Derpy moaned, resting herself against the table. One hoof twitched against the tabletop, the other worked madly at her own nethers as she dripped a mix of organic and synthetic juices all over the floor. “I feel some powerful manifestation coming...”

The Doctor thrusted her cock into her, causing a few small devices to fall from the table and smash on the floor. “It’s working!” he exclaimed. “Entropy’s rising!”

“Not only entropy...” Derpy muttered, clenching her muscles around the Doctor’s dick. To her surprise, he slowed down. “What’s up, doc?”

“I feel a strange tingling sensation in the back of my testicles,” the Doctor replied. “I have a feeling that I gathered all the data needed.”

“I’m pretty sure you left something out,” Derpy said. Her hind legs were shuddering slightly and her juices formed a small puddle on the floor. “Maybe we should try overloading the sensors?”

“But this may be dangerous!” the Doctor exclaimed. “We can get teleported to some distant planet! Or we may explode, leaving a black hole in the middle of the town!”

“My black hole will explode if we don’t try this!” Derpy groaned. “I have a feeling that atoms inside are in an excited state and I’m pretty sure that it’s not metastable!”

“Great whickering stallions!” the Doctor shouted. “What can we do?”

“There’s no way back,” Derpy cried. “The only thing you can do is to defuse it... by overloading it and causing a controlled chain reaction!”

The doctor looked at his dick. “So, it’s like a control rod?” he asked. “But it’s not made of cadmium!”

“It will do.” Derpy smirked. “Trust me, doc. Trust and thrust.”

The table screeched when the Doctor thrusted into Derpy’s butt, continuing his assault. Each move was bringing him closer to the heart of the darkness; he was about to discover the biggest mystery of the universe. His dick sat on the rim of grand discovery, and he needed only slide past the precipice to claim his ultimate prize of fame, fortune, and the glory of the scientific community.

He could feel the pressure building in his balls. Derpy let out a scream, her anus tightening around his cock and squeezing it. Suddenly, the table broke in two with a terrible snap. Derpy fell on the floor face-first, yanking the Doctor’s dick and pulling him behind her.

“Derpy, you okay?” the Doctor asked. The only answer was a series of moans. Derpy’s hind legs were twitching and a puddle of juices on the floor below her was growing quickly, matting her fur. The smell was overwhelming. The Doctor felt the urge to thrust and grabbed Derpy’s wings, pushing deep into her. She moaned, marecum flowing out of her.

The pressure and the smell were too much for him to handle. His dick twitched; the Doctor groaned, feeling his balls empty inside Derpy’s bowels, flood of cum hitting the walls of her dark cavity. The second squirt was just as powerful as the first, seed escaping Derpy’s anus and flowing down her thigh. She relaxed and clenched her ass again, causing more of it to flow inside of her, sipping every last drop.

“That was...” The Doctor panted, his dick slipping from between Derpy’s folds. “C-certainly... An interesting experiment...”

“Oh yeah...” Derpy turned back, watching the puddle of fluids on the floor. “Sorry for the table...”

“Oh, it was bound to happen, with entropy reaching such levels,” the Doctor replied. Suddenly, his eyes widened in horror. “Derpy! Are you hurt?”

“Oh, it’s nothing.” Derpy wiped blood from her nose. “I didn’t even notice it. That chain reaction was a rather overwhelming feeling.”

“Yeah, I felt something like that too.” The Doctor nodded, looking at his dick. “You were right about overloading the sensors...”

“See? Sometimes you just have to trust your assistant and take…” Derpy had to pause for a moment, still panting even as she finished, “Take the plunge.”

“The first step into a new world.” The Doctor lazily pulled his notepad across the floor. “No reward is without risk, I suppose. Anything you’d like to note?”

“Yeah. We should do this again.”

“I concur.”