From the first day they spawned changeling nymphs could alter their shape, although in the earliest stages of development their changes were entirely instinctive. Sharing, with hundreds of their siblings, a host little bigger than they would be when ready to emerge, their bodies needed to conceal their presence. The solution: long, thread-like forms that became longer, not bulkier, as they grew, and could snake and coil through their hosts' bodies without detection.
The only noticeable side-effect of their parasitism was the gradual decrease in the host's feelings of affection. This was something of a disadvantage of this stage of the changeling's life cycle. A fully-formed changeling could assume the form of their host's loved one and thereby continually arouse the host's affections, enabling an indefinite supply of nourishment. Incubated nymphs, by necessity invisible to their host, were in no position to do so. They had to rely on indirect love generation through their host spending time with, and reminiscing about, loved ones: time that decreased along with the host's loving feelings. Yet this was at most a minor inconvenience. The nymphs' food supply needed to last them only until their incubation period was over, usually around a week or so.
Now, Twilight's anti-disguise spell had returned the nymphs within her to their true form. They fought for room inside the alicorn's body while still feeding their appetites, which grew all the more voracious as the time to emerge drew near.
"You mean the changelings can disguise themselves as ... food? What have I eaten in the last week?" Pinkie Pie screamed in naked terror.
"No, you dawnhorse!" Twilight's pain, fear and reduction in love had stripped her of any social niceties. "The queen must have implanted them in me during the fight, probably while I was out. They've been feeding on me from the inside this whole time. That must be why I couldn't detect them. Why the queen didn't end my life when she had the chance."
"And why we'll be sorry if we cast the love wave," Cadance added sadly.
Spike inhaled sharply as he realised how close they had come to disaster. "If we hadn't delayed you, Twilight could have exploded."
"I may explode anyhow at this rate," screeched Twilight, her great bloated barrel heaving and pulsing like a queen termite. "Get me to the hospital."
With considerable effort, Rainbow Dash and Cadance hauled Twilight into the air and flew from the station platform, Cadance using her magic telekinesis to provide badly needed support to Twilight's tender abdomen. The others followed on hoof, Spike riding like a jockey on Shining Armor's back, until they neared the centre of Ponyville.
"Uh-oh," intoned Applejack.
Dozens of ponies were gathered in the town's main streets, which in itself was not unusual. However, they were no longer merely going about their everyday business. The sound of Twilight Sparkle bawling in agony and distress as she passed overhead had not exactly gone unnoticed, and once the townsponies had craned their necks to witness the abnormally outsized alicorn being ferried in the direction of Ponyville Hospital, then looked back to see Twilight's friends and brother galloping towards the same destination, they put two and two together and came up with trouble. They converged on the pursuing party and launched a cacophony of questions.
Applejack raised her voice above the hubbub. "Gang way, everypony, it's an emergency. Spike'll explain everything."
"Me?!" Spike blanched at the thought of having to tell the easily-spooked ponies that a swarm of changelings could descend upon the town any minute. Then he realised the alternative would be to help contain the changelings himself, possibly even facing one or more on his own. "Oh, yeah, me." Shining Armor stopped briefly to allow the baby dragon to dismount, then tore off after his little sister's friends.
The three airborne ponies neared the main entrance to the hospital, Cadance adjusting her magic to open the doors. Rainbow Dash led the trio to the front desk.
Pleasant Reception had ducked below the front desk, retrieving a patient's file, when the sudden commotion in the foyer caught her attention. She arose from her task and gaped at the sight. Thinking the receptionist was preparing to speak, Rainbow Dash immediately pre-empted her. "No time for your red tape, sister. Princess Twilight here needs surgery, like, yesterday."
Rainbow's brusqueness disarmed young Pleasant, who could only blurt out the first thing that came to her head: "I'm not a sister——".
"Less chat, more stat," barked Rainbow Dash, not caring whether that was correct grammar. "Emergency C-section. As in C for changeling."
Cadance chimed in, using a rather gentler yet equally firm tone, "You'll need to start your evacuation procedures soon." She and Rainbow Dash briefed the receptionist on the situation, struggling to make themselves heard above Twilight's increasingly hysterical moans.
The sunny yellow pegasus pressed a large button on her desk and spoke quickly but clearly into her microphone, her voice carrying to speakers placed throughout the hospital. "Attention all hospital staff. Nurse Redheart to reception immediately. Repeat, Nurse Redheart to reception immediately."
Within a few agonisingly long seconds a white earth mare wearing a nurse's uniform briskly arrived at the front desk. She and Pleasant had a short discussion before the nurse trotted back out through the double doors to the interior of the hospital. Twilight, Rainbow and Cadance waited another brief but unbearably anxious period until two burly pegasus orderlies burst into reception. One uttered a quick word to Pleasant, who delivered another message into her desk microphone: "Attention all hospital staff. Code black. Repeat, code black".
The two orderlies hoisted Twilight onto a gurney and wheeled her towards the operating theatre, guiding her past the staff and patients filing in the other direction. Rainbow Dash and Cadance followed, trying to encourage their quivering friend.
"Everything's going to be fine, Twilight," Cadance said soothingly.
"On what do you base that?" wailed Twilight.
"We're here for you, that's what," answered Rainbow Dash determinedly.
Normally, Twilight would have taken heart from such words. Now it was as if she had heard them from a pair of strangers. She had forgotten just how much courage she drew from her friendships, friendships that the parasites within her were greedily consuming. Fluttershy's words from that fateful night echoed in her mind: Love can turn the weak strong. Her love was all but gone now. In no state to reach within herself for her remaining reserves of love, she felt loneliness and despair overwhelm her. She wanted to curl into a foetal position but her monstrous belly ruled that out. Instead, she drew tight to the pillow on her gurney, closed her streaming eyes and submitted herself to her fate.
They arrived in the spotlessly clean, brightly lit theatre to find a four-pony operating team already scrubbed and ready to proceed. Doctor Horse, a caramel-coated unicorn, gestured towards the designated bed, which had been lowered almost to the floor to accommodate Twilight's copious barrel. Powerfully, yet with gentleness and precision, the orderlies placed the shaking Twilight upside-down on her bed and left the room to join the other evacuees.
Nurse Redheart, brandishing a transparent mask, moved towards the patient. The near-delirious Twilight fearfully drew her head back. "What are you doing? What is that thing? Get it away from me."
Sweetheart, the other nurse in the room, gently but firmly placed her lavender forehoof on Twilight's withers. "It's all right. This will take your pain away."
"Mask. Now," demanded Twilight.
As Redheart fixed the mask over Twilight's muzzle, Knockout, a gangling, powder-blue unicorn with curly white mane and tail, approached. Knockout's colthood had involved several humiliating years trying fruitlessly to gain prowess at various unarmed fighting disciplines, before discovering mid-bout that his definitive talent entailed spraying strong narcotic gas from his spiral horn. He inserted his horn into a round slot in the mask and told Twilight to relax.
"'Relax'? Twilight repeated, the mask thankfully muffling her voice. "How can you possibly expect me to——?" Knockout's magic vapour took its effect and Twilight drifted into unconsciousness.
The two nurses began shaving Twilight's abdominal hide, which was no easy feat considering the bulges continuously shooting out. The two unicorn stallions telekinetically smoothed out Twilight's belly as best they could as the nurses proceeded with their delicate work.
Pleasant Reception entered the theatre. "Doctor Horse, the hospital's been fully evacuated."
The doors behind her swung open, knocking the poor pony flat on her face. Shining Armor charged into the room, Twilight's breathless friends accompanying him.
"Except for our visitors, of course. Here, you'll need these." Dazedly, Pleasant Reception handed the visitors a cluster of facial masks and mane caps, then stumbled out towards the emergency exit. Rainbow Dash followed her out, ensuring she didn't detour into any supply closets or restrooms, then raced back to the operating theatre.
Doctor Horse was the most experienced surgeon in Ponyville, and could not have asked for a more reliable team. Yet he had never performed an operation such as this. The closest he could remember was that ectopic pregnancy years ago, and he expected there would be a considerable difference between saving the life of a helpless, premature pony foal and deflecting a swarm of savage changeling nymphs. He carefully guided his scalpel towards Twilight's bald abdomen, which was now stretched almost to the point of translucency.
As soon as he made his incision, the nymphs started excitedly pushing their way out, threatening to tear their host apart.
"Forceps."
At Horse's emphatic but unemotional command, Redheart quickly passed him the instrument. The surgeon took them in his telekinetic aura and pressed them firmly down on the uppermost changeling fighting to emerge. Simultaneously, he guided the scalpel through Twilight's flesh. Yet the pressure from within quickly became too great. One, two, half a dozen glossy black figures, still glistening with Twilight's internal fluids, shot into the air above the operating team and spread their perforated wings and limbs.
Twilight's five friends drew closer together, simultaneously seeking and providing mutual protection. Shining Armor and Cadance did likewise. The gravity of the situation brought the love the ponies had for one another to the surface, instantly detectable to the changelings. The aroma from the five reminded the hovering nymphs of the feast of phileo, mixed with agape and storge, that they had gorged on within their former host. The two larger ponies, however, were producing a different kind of love altogether, a powerful, irresistible cloud of the changeling's most treasured flavour of love: eros. Hissing with relish, the nymphs swooped down towards Princess Cadance.
Shining Armor stepped in front of his wife, caught the attackers in his magic grip and dashed them onto the hard floor, just as six more nymphs followed their siblings out of Twilight's open abdomen. Rainbow Dash arced at them with lightning speed and expert precision, gathering the nymphs in her forelegs and tackling them to the floor. Applejack, Pinkie Pie, Rarity and Fluttershy joined Rainbow Dash, causing a melee to erupt, while a dozen more buzzing changelings dived towards the royal couple.
Doctor Horse and his team did their best to focus on their fragile patient despite the battles raging around them. Their professional detachment meant the only love emanating from them was agape, nourishing to the changelings but not especially appealing to their tastes.
A cluster of nymphs latched onto Shining Armor's haunches, savaging hs hide with their sharp fangs. The muscular stallion bucked them clear and tele-slammed another group who aimed for his vulnerable face and neck. He fought with an unbridled ferocity that stemmed from more than mere protectiveness. He still resented his inability to take direct offensive action against the dragon at the Crystal Empire, and he felt he had to atone somehow.
Cadance lured a group of changelings as far from Twilight and the desperately concentrating operating team as possible, then started firing bolts of energy at her attackers from her horn. The fast-flying nymphs, criss-crossing across Cadance's line of sight, were difficult targets to hit. They bombarded her from all directions, forcing her to resort to the unfamiliar measure of hoof-to-hoof combat. The graceful alicorn battled gallantly but the changelings' relentless assault soon ground her determination into frustration which, in turn, gave way to distress. The nymphs began ejecting adhesive green silk over her.
Hearing the cries of his beloved, Shining Armor started remotely dragging the nymphs off his wife and casting them aside. Witnessing Cadance getting the worst of the fight intensified his love, attracting more changelings to him. His battle-honed reflexes enabled him to counter their attack, anticipating their moves and swatting them from the air with powerful hoof-strikes. Less than half a minute later, the nymphs lay stunned around Shining Armor, who stood panting for a few seconds before walking towards Cadance. Every step caused him pain which he strived to conceal.
As the white stallion magically cleared the sticky threads from the unsteadily rising Cadance, he noticed that the fighting on the other side of the room had died down. He looked up to see Applejack, Rainbow Dash, Pinkie Pie, Rarity and Fluttershy emerge from behind the operating team. They were dishevelled, but wore smirks of triumph.
"Nice work, mares. Now we just have to——."
Smirks of triumph.
Which meant they were not wearing masks.
Nor mane caps.
Before either pony could react, the five disguised changelings blasted with blinding speed at Cadance, slamming her against the wall with a force that knocked the wind from her lungs and the consciousness from her mind. Shining Armor lunged furiously at the attackers, letting his own guard down. Two nymphs leaped onto his sensitive muzzle, where his magic range was at its weakest. They raked at the thin layer of flesh and guzzled down the unicorn's love. He reared up, exposing his underbelly to the arrow-like attack of the other three nymphs. He violently jumped and twisted, trying to shake creatures off, but they clung on doggedly, evading his magic and his trampling hooves.
Battered and dazed, Applejack, Rarity, Pinkie Pie, Rainbow Dash and Fluttershy — the real ones — struggled vainly against the silken threads pinioning them to the floor, while Cadance lay motionless near her gradually weakening husband.