Applejack resisted the urge to pace up and down the lab with great difficulty. The only thing keeping her planted on a chair in the lab was the fact that she didn't want to distract the medic running tests on Fluttershy's blood. Rainbow and Rarity were similarly seated, talking quietly about the raiders that had tried to take their friend.

Elder Lyons had suggested that the girls leave the lab so that the medic could work in peace, something Applejack had agreed to do even if she hated the idea, but the medic had stated that he liked having company while he ran the tests. Only Sunset had actually left, offering to pop in on Twilight and Pinkie to let them know what was happening before going to look after Fluttershy; ostensibly to give the overworked Brotherhood medical team one less job to do, but Applejack suspected that she just wanted to be alone for a little while.

"How much longer until we know if Fluttershy was drugged or not?" Rainbow asked suddenly.

"Rainbow, don't distract him!" Rarity hissed indignantly.

The medic waved a hand absently from his terminal next to a medical machine of some sort. "It's fine, I'm actually almost done." He entered a command into the terminal, then a few seconds later a beep came from the machinery and several lines of script slowly appeared on the screen. "Hmmm, she doesn't have any of the known chems in her system, which is a good thing, but she does have an elevated white blood cell count."

Applejack shifted her hat so she could scratch her head. "Is, uh… is that a bad thing, or…?"

"It's possible." The medic stood and set about fiddling with equipment that Applejack couldn't identify. "It could just be because she's stressed, but it could also signify an infection of some kind. I'd like to run some tests for viruses and set up a blood culture to see if we've got a bacterial or fungal issue, but first I'm just going to toss a sample of her blood under a microscope to see if I can spot anything out of the ordinary."

Applejack nodded, privately glad that she could at least follow what he was saying, if not what he was doing. Rainbow shuffled impatiently as the man set up the microscope, but a quick glare from both Applejack and Rarity kept her quiet.

"Right, let's see what we've got here," the medic muttered as he put his eye to the microscope. He fiddled with a dial on the side a bit, then whispered, "Gotcha." A moment later he frowned and did a double take. "What the…?" The man reared back from the microscope and blinked a few times before looking through it again. "What the fuck is that?"

"What's wrong?!" Rainbow snapped.

"Her blood cells, they're-" The medic snapped his head up, then darted over to a pile of clipboards, throwing them aside one by one until he found what he was looking for. "No… no that can't be right."

"Doc? What's. Wrong. With. Fluttershy?" Applejack growled.

The medic shook his head. "Her blood cells appear to be changing somehow, even as I watch."

Rarity stepped over to the microscope and took a look for herself. "Oh my, that's odd. Do you think it could be her magic that's causing that?"

"I highly doubt it, Miss Sparkle's blood didn't do that when we checked hers," the medic replied. "I've never seen anything like it. It does somewhat resemble the descriptions of the effects of FEV on blood cells, but it's much-"

"FEV?!" Rarity and Applejack yelled in unison. Rarity snatched the clipboard from the medic and scanned it frantically as Applejack asked, "You mean that stuff that turns folks into Super Mutants?!"

"Wait, Fluttershy's gonna turn into a Super Mutant?!" Rainbow cried.

The medic crossed his arms and shook his head. "I don't know, and let's not jump to conclusions. It certainly resembles what I've heard of FEV, but it's working way too fast. It's equally likely that it could be something else that she's been exposed to."

"Can't you just take a look through the microscope and see if it's FEV?" Applejack asked.

"The FEV is a virus, it's too small to be seen on a standard microscope like this," the medic replied. "Do you know if Fluttershy has been exposed to any unusual substances recently?"

Rainbow shrugged. "I don't think so? Oh, wait! There was that green stuff she got splattered with back in Vault 87."

Applejack sucked in a breath at Rainbow's words. "Green stuff? Ain't that…?"

"FEV," Rarity confirmed in a horror-struck voice. "Why didn't any of you tell us that Fluttershy had been splashed with something so toxic?!" she cried angrily.

"H-hey, we didn't know it was dangerous!" Rainbow replied quickly. "She wasn't bothered by it at first, then with everything that happened with the Enclave afterwards, we just forgot." She looked up at the medic desperately. "There's gotta be something we can do, right? Some sort of cure or… or something?"

The medic opened his mouth to reply, then frowned and looked back at the microscope. Applejack followed his gaze and gasped as she saw wisps of smoke rising from the glass slide containing Fluttershy's blood. "What the heck? What's it doing now?"

"FEV is highly corrosive, it must have replicated enough to actually eat through the glass," the medic replied as he carefully removed the slide before it could damage the microscope. "But how is it reproducing so quickly? And how did it not burn her skin on contact?"

"Well, Fluttershy was ponied up when she got splashed. Do you think that has anything to do with it?" Rainbow suggested.

Applejack's blood ran cold as another thought occurred to her. "Hang on, that stuff is in Fluttershy's blood, right?" The medic nodded. "Then doesn't that mean that that stuff that just burned a hole through solid glass is growing inside her body right now?"

The others stared at her in frozen shock for a second, then charged for the door at top speed.

---

Sunset ran a hand over her face as she made her way towards Fluttershy's room. She was reaching the end of her tether; if anything else bad happened she wasn't sure that she'd be able to handle it without completely losing her mind.

The only silver lining that Sunset could see at the moment was the fact that Rainbow had managed to rescue Fluttershy so quickly. Of course, it was still an insanely reckless thing for Rainbow to do and Sunset fully intended to chew her out for it, but that could wait until Fluttershy was healed and everything had calmed down again.

Halfway down one of the infirmary corridors Sunset finally reached the room where Fluttershy was being kept. She paused outside the closed door and took a deep breath to mentally prepare herself for the sight of another friend unconscious. When she was ready Sunset opened the door and stepped inside, only to gasp in surprise when she saw Fluttershy sitting up on the edge of the bed, clearly awake and gently removing an IV drip from her arm.

Fluttershy tossed the IV aside and glanced up at the sound of the door opening. Her eyes were watery and unfocused, and her face was dripping with sweat. "Sunset?" She tried to push herself to her feet, but her legs wobbled beneath her and she tottered forward like a drunkard.

"Whoa!" Sunset darted forward and caught her before she could fall over. "It's okay, I've got you. Let's get you back on the bed."

Fluttershy shook her head slowly. "N-no, I need… nursing kit."

"Nursing kit?" Sunset looked around the room, quickly spotting Fluttershy's bag on a desk by the door. "I see it, what do you need from it?"

"Blood pack," Fluttershy said roughly.

Sunset raised an eyebrow dubiously, but nodded and gestured to the bed. "Okay, you just sit here for a second then, and I'll fetch a medic to set it up for you."

"No," Fluttershy hissed. "Need it now."

"You're not in any shape to set it up yourself," Sunset said gently. "It's okay, it'll take me two seconds to fetch a medic and bring the-"

"I said no!" Fluttershy slammed a fist into the filing cabinet beside the bed, the metal crumpling like paper beneath her hand.

Fear gripped Sunset at this sudden display of anger and raw strength. She backed away slowly as Fluttershy started growling deep in her throat. "Uh, Flutters…? Are… are you okay?"

With a feral snarl Fluttershy grabbed the filing cabinet and hurled it against the opposite wall, sending loose paper flying everywhere.

Sunset skipped backwards until she felt her back slam into the door. She watched in mounting horror as Fluttershy hissed and snarled, clutching at her head and writhing as if she was in agony. Finally, with a flash of light from her Geode that pulsed over her entire body, Fluttershy abruptly hunched over with a scream as an immense pair of bat-like wings exploded from her back in a welter of blood.

Time seemed to stand still in the wake of that awful moment. The room was silent save for Fluttershy's ragged breathing and the faint drip of blood from her new wings. Her knuckles cracked as she flexed her hands, displaying inch-long curved talons in place of her fingernails.

Sunset, frozen in place by the door, could only watch in horror as Fluttershy slowly looked up at her. A jolt of pure terror shot through her as Fluttershy's hair fell away from her face to reveal blood-red eyes and a vicious-looking set of elongated fangs.

Somehow, Sunset could sense an unnatural hunger in the burning gaze that Fluttershy directed at her. Sunset's entire world had suddenly been flipped on its head, but she didn't have time to try and figure out how things had gone so wrong as Flutters took a measured step towards her.

In a flash of inspiration, Sunset glanced inside the nursing kit on the nearby desk and snatched a blood pack out of it. Fluttershy's eyes instantly locked onto it. Gratified and horrified that her theory was correct, Sunset tossed the blood pack at her friend.

Fluttershy caught it in her teeth and bit down hard, piercing it with her fangs, and drained the whole thing in a flash.

Sunset gaped as Flutters spat out the empty pack and began advancing on her. "I, uh, guess that wasn't enough," Sunset said with false confidence as she reached blindly for the door handle, not daring to take her eyes off her suddenly vampiric friend. "W-why don't you wait here and I'll, uh, go get some more."

A loud snarl tore from Fluttershy's throat as Sunset found the handle and wrenched the door open, quickly ducking out and slamming it shut with both hands. A heartbeat later the door was smashed off its hinges, knocking Sunset clean off her feet and landing on top of her as she crashed painfully to the floor.

Sunset didn't have a chance to get her bearings before the door was ripped off her. Fluttershy casually tossed it away down the corridor before bearing down on Sunset. Just before fangs reached flesh something barreled into Fluttershy's side, pitching her off Sunset and knocking her sprawling.

"Damn it! We're too late!" Sunset looked up to see Rainbow Dash staring at Fluttershy.

Sunset opened her mouth to ask what was going on, but Fluttershy was already back on her feet, hissing like an enraged cat. She crouched as if she was about to pounce, then suddenly her head snapped around as something behind her got her attention.

A moment later a power-armored Knight stepped into the corridor. "What the- what's going on?"

Fluttershy let out a piercing screech and launched herself at the Knight. He must have assumed that she wouldn't be able to harm him in his armor, as he didn't react until her claws gouged deep furrows in his chestplate. The Knight cried out in shock as she raked her claws across his helmet in a shower of sparks.

As the Knight backed away Rainbow surged forward in a blur, sweeping Fluttershy's legs out from under her. "Quick! Hold her down!"

Fluttershy tried to scramble to her feet, but the Knight grabbed her arm, dragged her off-balance, and forced her to the floor again. The moment she was down he quickly pinned her, planting one hand on her shoulder and the other on her outstretched wrist so she couldn't gain the leverage to shift him. Fluttershy kicked and flailed around wildly, but the sheer weight of his armor was enough to counter even her newly enhanced strength.

Sunset just watched from where she lay on the floor. She heard footsteps approaching rapidly from behind, but her eyes were locked on Fluttershy's. Seeing her friend in that state, her feral screeches of frustrated rage echoing down the corridor, Sunset felt something within her soul shrivel up and die.

Next Chapter: Chapter 69 - Silver Lining Estimated time remaining: 30 Hours, 31 Minutes