Author's note: an elaboration of the idea found in http://www.fluffybooru.org/post/view/3629
 
>”Sir, you need to see this.”
>The voice of the assistant sounds incredibly shocked, even over the crappy walkie talkie.
“What's going on?”
>”One of the population control experiments gave birth to a...I don't even know what the hell this thing is.”
“Very well, I'm on my way.”
>You move through the building until you reach the east wing.
>This part of the facility is where everyone is working on fighting the urge of the fluffy pony to have kids.
>Everything from chemical sterilization through food to reset reprogramming is being tried.
>You see the assistant waving to you through one of the large windows.
>In her arms is a very agitated grey earth fluffy, fighting to get free.
>Only when you enter can you hear her cries.
>”Nuuuu! Pwease down, Nikki nee' gif babeh owwies!  Nee' gif owwies!  Pwease down!”
>In Nikki's bed are three dead foals, their heads bitten completely off.
>Outside of the bed on the white carpet is a fourth foal, a still-living unicorn.
“What the hell...”
>Its fluff is a deep blue color; its mane is a maroon red.
>It chirps loudly, eyes not yet open.
>You pick it up.  After turning it over in your hands a few times, you can barely believe it.
>This foal has two heads.
>In fact, it appears to be two front halves joined at the base of the thorax.
>Overall, it's about one and half times as large as a regular foal.
>When it doesn't feel any fluff on your hand, it begins chirping with fear, legs trying to pull it away in opposite directions.
>”What should we do with it?”
>You think for a moment, ignoring Nikki's desperate pleas to let her kill her child.
“Call genetics.  I'm going to take this thing to one of the regular dams.”
>If this foal is a mutation, it may be a goldmine of data about the fluffy pony genome.
>Even if it's just a set of conjoined twins, it can be of use to the reproductive department.
>This foal will be kept alive.
>At least, for as long as it doesn't have to excrete waste.  There appears to be no way for it to do so.
>Twenty minutes later, the conjoined foal is with its new mother, a purple pegasus named Fiona.
>Fiona's latest litter was seventy-five percent stillbirths.  She is extremely protective of her one living foal.
>She looks at the new, strange baby with trepidation.
>”Babeh sickies?” she asks repeatedly.
>Her brain cannot comprehend what she's looking at.
>”Fiona, this baby is very special,” the geneticist says.  “It needs a good mommy like you.”
>”Feena goo' mumma...babeh no wook wike babeh,” she replies, watching it crawl toward the sound of her voice.
>Very gently, she pushes it away.  “Babeh...babeh dumb...”
>Her biological foal, hugging her belly fluff, chirps loudly as she moves.
>She immediately comforts it with quiet babbling.
>This particular geneticist is a bit of a hard-ass.
>You watch as she quickly intervenes to stop the rejection process.
>”Fiona, feed this baby.”
>”Babeh dumb, no wan'.”
>”Fiona, feed this baby right now.”
>”No wan', babeh sickies, goo' babeh haf sickies fwom dumb babeh!”
“Let's just reset her, Cynthia.”
>”No, I'm going to make this stick the old-fashioned way,” she replies.
>She reaches down and plucks the green pegasus foal from Fiona's belly.
>”Nuuuuuuu!  Pwease gif goo' babeh!” she screeches, terrifying the conjoined foal near her.
>”Feed your new baby or you'll never get this one back.”
>”Gif babeh!  Babeh nee' mumma!  Nee' miwkies an' wuv!”
>”Feed it, Fiona!”
>The green foal chirps with terror as Cynthia squeezes it slightly.
>”Gif nummies!  Gif nummies to new babeh now!” Fiona wails, broken by the panic of her foal.
>She pulls the conjoined foal over with her forelegs and guides it to a teat.
>”Good girl.  I'm keeping this one until your new baby is done.”
>”Gif nummies, no huwt babeh, babeh goo' babeh,” Fiona mumbles.
>She feeds one head, but the other chirps loudly.
>”No cwy, babeh haf nummies!” Fiona reassures it.
>It still chirps.  Confused, Fiona tries to contort herself so the other teat reaches its mouth, but she can't.
>”Just turn it around, Fiona.”
>”Tuwn 'woun'?”
>”Christ, you're a moron.”
>Cynthia turns the foal around so the other head gets a shot at the teat.
>”Like that.”
>”Babeh go 'woun', haf nummies 'gain?”
>Fiona is even more confused than before, not understanding why she has to feed the same baby twice.
>You and Cynthia leave her to deal with the foal.
>This room is equipped with cameras for all-day monitoring, as Fiona is one of the mares that belongs to the genetics department.
>In fact, their experiments are why she only has one foal alive out of four.
>Half an hour later, you check on the feed from Fiona's room.
>Her foal and the conjoined foal are sleeping soundly next to their mother.
>Just as you're about to walk away, you see the conjoined foal wake up and start moving around.
>One head expels something that's too dark to be milk vomit.
>It chirps fearfully, the sound muffled by whatever it is coming out.
>”Babeh?  No cwy, mumma hewe!” Fiona says as she startles awake.
>”No smell pwetty...babeh make poopies,” she says, gently moving the foal away from the mess.
>It shat out of its mouth.  The anatomists are going to have a field day with this thing.
>By the next morning, the two-headed foal is still kicking, but the heads are acting much differently.
>Fiona refuses to feed the head that keeps shitting.
>”Dat no babeh, dat babeh poopie pwace,” she says.
>The dominant head now gets all of her attention.
>It suckles happily alongside its pegasus sister, while the inferior head chirps pathetically for milk.
>While on the teat, more liquid shit dribbles out of its mouth.
>”No make poopies on mumma!” Fiona complains with a scolding tone.
>”Wuv!” chirps her green foal, already learning basic words.
>”Wuv babeh, no cwy.”
>The two-headed foal only makes chirping noises.
>The fun continues as the hours pass.
>Fiona has finally noticed that the 'poopie pwace' of her new baby talks like a baby.
>She can't come to terms with it.
>”Poopie pwace talkies?  Feena poopie pwace talkies too?”
>While her foals sleep, she spends several minutes moving in a circle, trying to talk to her ass.
>”Poopie pwace fwiend?  No talkies?”
>Her foals awake, and she waddles over to tend to them.
>The dominant head gets a meal, as does the green pegasus.
>The other head mewls constantly for attention, and is ignored.
>More excrement leaks from its mouth as it cries, turning the chirps to gurgles.
>Fiona scolds it, too.  ”Poopie pwace no talkies, babehs haf nummies.”
>This repeats the second day, but a new problem is arising.
>The two-headed foal is taking twice the milk to support the half that's not eating.
>The other foal is beginning to experience a shortage.
>”Why babeh haf aww nummies?  Goo' babeh nee' nummies!”
>It ignores her completely, suckling for thirty minutes at a time.
>”Wuv!  Mumma!  Hung'y!” the other foal cries, nipping at a teat that isn't bearing much milk.
>”Sowwy!  Babeh take aww nummies!”
>The other foal still hasn't learned any words.
>The dominant head chirps loudly whenever another fluffy talks, as if trying to mimic their words.
>The other head wheezes and emits a wavering squeak.  Shit leaks from its mouth constantly.
>When Fiona's stacked blocks fall over and scare the foals, the results are predictable.
>The green foal squirts piss and shit fearfully, running around and hiding in Fiona's fluff.
>The two-headed foal, however, gets nowhere, its two pairs of front legs tearing in opposite directions.
>Shit also squirts from the inferior head's mouth, causing it to become terrified, which frightens the dominant head.
>This causes even more shit to squirt out, prolonging the cycle until the foal's bowels – or whatever is in there – are emptied.
>The inferior head is so traumatized, it faints.  The dominant head has to use its half of the body to drag the dead weight around.
>”Babeh sickies?” Fiona asks, hugging the foal.
>It still just chirps back at her.
>Another researcher watching the footage surmises that the foal actually needs more milk than it's getting to support both brains.
>If it took any more, it'd probably drain Fiona dry.
>By the third day, the two heads are in wildly different states.
>The dominant head is as happy as can be, trying desperately to play with its green sibling.
>It can't accomplish this because the inferior head is becoming sick and lethargic.
>The blue foal drags itself around after the green foal.
>The green foal wants nothing to do with it, preferring to lead it away and then run back to its mother's teat to suckle.
>Fast learner, that one is.  You jot down a reminder to send it to the behavioral department when it gets weaned.
>The blue foal is becoming scared of itself. The dominant head feels four legs, but has control of only two.
>It chirps as loudly as it can manage.  Fiona doesn't understand what's wrong.
>”Babeh cwy?  Babeh no haf owwies, babeh no cwy.  Mumma hewe, babeh happy!”
>It can't talk back to her; even a simple 'weggies owwies' in a scared tone would tell her something is amiss.
>Then she'd call for a human, like she does whenever her babies talk to her about 'owwies'.
>The inferior head, meanwhile, just squeaks quietly.
>Its facial fluff is matted and caked with waste.  Even its nostrils are brown.
>Its eyes have become cloudy over time, lacking the sheen of the other foal's.
>By afternoon, the dominant half of the foal spends most of its time running away from the inferior half.
>Every time the inferior half squeaks in protest, the dominant half's fear makes it shit itself.
>By the time your shift is over, the inferior half no longer squeaks.
>On the third day, the inferior half is quiet, but still alive.
>It breathes languidly.
>The dominant half isn't in much better shape.
>The forceful expulsion of shit through one of the digestive tracts means that the foal is now ravaged with infection.
>Fiona finally realizes that something is wrong.
>”Hewp!  Babeh sickies!  Babeh haf owwies, hooman hewp pwease!”
>The dominant head chirps loudly in concert with her, desperate for some sort of care.
>The inferior head's eyes are barely open.  Its mouth only moves when fearful shit is forced out of it.
>The foal drags itself around helplessly.  Soon, it becomes apparent that the inferior half has died.
>The living half screeches and squeaks powerfully, no longer feeling vast parts of itself.
>”Gif huggies!  Babeh no cwy, huggies make owwies go 'way!”
>The other foal is scared out of her wits, hiding behind Fiona.
>Without two hearts to pump the higher blood volume, and two sets of lungs to oxygenate the blood, the dominant half begins suffering greatly.
>After a while it just flops over and gulps air, trying to close the oxygen gap.
>”Pway?” the other foal asks, nudging it gently.
>”Babeh no pway, babeh sickies, hooman pwease hewp babeh,” Fiona sobs.
>Moments later, the dominant half's overworked heart seizes up.  It shudders violently before falling still.
>”B-babeh?”
>The foal's corpse is removed immediately for examination.
>It's about a week later when you hear that the inferior half of the foal only had an esophagus leading into the dominant half's intestine.
>The inferior half was constantly swallowing shit, forcing it down, only to throw it up when too much accumulated.
>As for how the foal was born this way, no one is sure.
>The leading theory is that the zygote was somehow damaged during gestation.
>The genetics department, of course, is now trying to replicate the two-headed foal.