Twilight knew the principles of wing anatomy from her biology classes in school; when you broke them down to their most basic elements, they were nothing more than an assemblage of hyper-sensitive nerve endings covered by bone, muscle and feathers. They had evolved this way with one purpose in mind: to aid a pegasus pony in high-speed flying by acting as additional sensory organs. Flying at speeds so close to the sound barrier required an awareness of environment that a normal pony brain wasn't equipped to deal with, thus their wings had developed as an early warning system of sorts, and a well-trained pegasus flier such as Rainbow Dash or the members of the Wonderbolts would be capable of making minute corrections quite literally faster than the eye could follow.

        But seeing a set up close was something else entirely; with the tip of her hoof, Twilight traced the delicate network of bones that formed the skeleton, being careful not to apply too much pressure. Even her dainty touch was enough to elicit a soft gasp from Fluttershy, and the unicorn couldn't help but smirk to herself at the sound. Like birds, the bones of pegasi wings were light and hollow making them perfect for flight, but it also meant that they were incredibly fragile, too. She couldn't recount the number of times Rainbow Dash had ended up in A&E because of an accident. The only time they were meant to receive direct physical contact was during preening, and Twilight was aware that this was something that pegasi preferred to do in private.

        She was also aware of the fact that it was uncommon for pegasi to allow somepony else to groom them; whether it was a cultural taboo or simply out of practicality – it wasn't feasible, of course, to have somepony follow you around all day just to tend to your wings – Twilight was less certain. Maybe they felt the same way about it as other ponies did about having somepony else wash their private parts? The unicorn felt a warmth rise up in her chest as she tried to picture Fluttershy doing … that to her. Later, maybe, when we've been going out for a bit longer.

        Finding bits of leaves, dust, dirt and Celestia knows what else mired within the pretty yellow feathers of Fluttershy's wings, Twilight felt an expression of distaste creeping on to her muzzle. Maybe they just didn't like to inconvenience anypony else by subjecting them to all of this detritus? If this was how bad it got after one day without flight, what would it be like with somepony who flew all the time? As she followed the many splintering lines that formed the finespun veins of her wings' circulatory system, their reddish hue diffusing to a pale indigo in the moonlight, Twilight remembered how, as a filly, she'd often wondered what it would be like to have wings.

        Oh, it was possible to do, of course. Anything was possible with magic, after all, but they would not be true wings. She would feel nothing from them as they would be nothing more than artificial constructs that would allow her to fly while offering her none of the sensations associated with flight. Teleportation was nice – much more efficient, anyway – but to soar through the air, unfettered by gravity, must be a wonderful feeling. The rush of air in your mane and feathers as you sped through the skies … Twilight still couldn't quite believe that Fluttershy hated flying as much as she did, but then again the unicorn wasn't the one who'd nearly plummeted straight into the ground as a mere filly. “Too much?” she asked earnestly, a feeling of giddiness swelling in her bosom at the way the pegasus was squirming as her hoof brushed against the plumate inner feathers on the lower part of her wing.

        “No, no, everything's fine,” Fluttershy replied hesitantly, blushing furiously and shifting awkwardly on the bed as she adjusted her tail in order to make sure that everything was properly covered down there. Twilight wasn't slow to notice the manner in which she'd clamped her thighs together either.

        Hearing that apprehension in the pegasus' voice gave Twilight pause and she stopped her gentle massage. Though their relationship was still in its relative infancy, they'd talked a number of times about boundaries: the unicorn knew that Fluttershy was a timid soul, and that she had her issues with intimacy. Twilight felt much the same way herself, and she had no problem with giving Fluttershy as much time as she needed to get comfortable with the idea of proximity. Up until now, the furthest that they had gone was some light kissing and fondling. “I'm being pushy, aren't I?” Twilight said softly. She released the wing from her grasp.

        The sudden return of the weight, slight as it was, caused Fluttershy to grunt. She flexed the appendage experimentally a few times, muttering something about how it felt like it belonged to a stranger. The pegasus turned to face Twilight. “It really was fine,” she said, more insistent this time. “It's just that it's also-” her eyes quickly flashed in the direction of her hindlegs “-very tender.”

        It took Twilight a few moments to understand just exactly what Fluttershy meant, and realisation only fully dawned when the pegasus' hindlegs twitched. “Oh,” she said, a devious smirk creasing her muzzle. “I see.”

        Feeling curious despite herself, Twilight lowered her head to the pegasus' wing, taking it once more in the grip of her magical field – she didn't want Fluttershy to accidentally injure herself by trying to wrench it away when she went to work on it – and pressed her mouth tentatively against the downy fluff on the underside of her wing. A pant of excitement from Fluttershy encouraged her to continue and she allowed her tongue to slip out from between her lips, and she drew a ragged trail of saliva along the length of the ulna. The flavour of her wing was a mixture of the pegasus' own natural earthy tang as well as the innumerable other essences that had gotten lodged in there in the course of her day. Not exactly unpleasant, Twilight reckoned, but hardly a taste explosion either.

        In order to keep from crying out at Twilight's attentions, Fluttershy had buried her face in a pillow, but the unicorn could hear the odd squeak creep out of her muzzle all the same; the feeling in her wing was somewhere between an itch that she longed to scratch and a tickle that permeated the appendage, and it was sending minor tremors surging throughout the rest of her body, too. The same sensitivity that made pegasi such good fliers could also be applied for more carnal purposes, as Twilight was quickly discovering.

        She watched with a detached fascination as Fluttershy's back arched, her spine dripping with sweat, as she repeated the licking action on her humerus; it was interesting to see the pegasus, normally so demure, burning with such energy. It was almost an obscenity.

        Fluttershy's prim moans soon took on a new intensity as Twilight continued her motions, using her long, flexible tongue to trace each of the tiny bones that made up the structure of her wing; the pegasus felt a pressure building up within her, seemingly centred on her pelvis, and she gasped loudly at the sensations flooding through her. “Twilight,” she said, salt water running down her cheeks as unfamiliar but pleasurable feelings waged war against her own staid nature in a battle for supremacy, “you … you need to stop doing that.” Her hindlegs gyrated, getting trapped in the covers, and she could feel her tail swishing back and forth agitatedly, as the spark between her thighs continued to grow until it became fiery in its potency.

        The response that she got was not the one that she had expected; rather than easing up, Twilight attacked her wings with a renewed vigour. She took individual feathers into her mouth, teasing the soft tufts and stretching them out to their limits, before releasing them and moving on to the next one in the sequence. The unicorn could feel her own amorousness increase in response to the writhing pegasus squirming so sensuously underneath her. It was an incongruous image for Twilight, and felt a slight disconnect between what she knew of Fluttershy and what was actually happening between them right now. She'd by lying if she said it wasn't giving her a charge, though, to have the pegasus so completely at her mercy.

        She wondered just how far this would go before Fluttershy's half-hearted protestations – that she hadn't repeated her desire to stop in some time suggested to Twilight that she was just a little bit overwhelmed and not actively disliking what was happening to her – became a genuine desire to stop. There was pushing, then there was pushing, and she didn't want to be responsible for taking Fluttershy into territory that she was not okay with.

        Pushing her doubts aside, she bared her teeth in a provocative leer and tugged at the soft, stretchy flesh where Fluttershy's wing met her body; it was a lot thinner than Twilight had been expecting it to be, and each nip forced squeaks that skirted the border between pain and pleasure from the pegasus, though they were muffled by the pillow that she was practically eating at this stage. The stuffing was soaked through with a mixture of her drool and tears. Twilight's incisors scraped the supple skin, but she took great pains to avoid breaking the sinewy tissue there before dragging her teeth along the gossamer-like primary feathers that demarcated the outer edge of her wing. The pinions were a lot more flimsy than the ones on her underside, Twilight realised, and she supposed that made sense: they didn't deal with as much stress as the others and were mostly just for redirecting the flow of air for take-off and landing.

        Fluttershy squeaked as a deluge of new sensations ebbed and flowed through her body; her wings in particular, usually forgotten by her side until something reminded her of their continued existence, felt as though electricity were coursing through them. Even though Twilight was only tending to one of them, the responses were mirrored in its twin, but her mind was too busy with other matters to give this quirk of pegasus biology much thought. The itch, as she thought of it, suffusing her wings was growing and feeding back into the ever-growing sense of warmth building up in her abdomen.

        Twilight gradually became aware of the change in pitch and tempo of Fluttershy's moans and her ears perked up; her teeth seemed to have found a particularly sensitive spot, if the sudden redness of Fluttershy's chest, neck and muzzle that she witnessed was anything to go by. Her own muzzle became more insistent, teeth, lips and tongue working at the tender flesh until, finally, Fluttershy's beryl eyes became glassy and unfocused.

        Suddenly, an animal howl filled the room and Twilight literally backed away in alarm, almost falling off the bed in the process; she had difficulty believing that the sound was emanating from Fluttershy's throat – muffled partly by the pillow in her mouth – even though she was sitting right next to her while it was happening, and her heart thrummed madly against her ribcage.

        “Oh, Tartarus,” Twilight said, hissing the words out through gritted teeth. The enormity of the last few moments hit her with the force of a thunderbolt. “Fluttershy, are you … are you okay?” For a long moment, the unicorn felt nothing, could do nothing, and if you were to look into her eyes at that moment you would see nothing but dull incomprehension at what had transpired. She did not see Fluttershy's quaking form, nor the cheerful pictures of friends and family on the walls, but her attention had been transfixed by some distant point on the horizon. Her mind had gone swimmy and numb as she tried to process what had just happened between the two of them.

        The strangled half-sobs, the shivering pegasus next to her making those noises, didn't belong to any sort of reality that Twilight Sparkle was familiar with. “Fluttershy …?”

        When the crying didn't quite stop, Twilight's addled mind finally managed to come somewhat to grips with the situation and she placed a comforting hoof on the pegasus' withers and stroked her back gingerly. Leaning in close to her muzzle, the unicorn's concerned eyes could only see a mask of pink hair, snot and tears. It was difficult to believe that this reticent creature, whimpering quietly into a pillow, was actually older than her by a couple of years. Moving slowly so as not to startle her, Twilight brushed Fluttershy's mane back until she could see her face again. She was bright red, gasping and panting, and Twilight felt a pang of regret for what she had just done to her. “Are you okay?” Twilight asked again.

        Still no answer.

        Twilight nudged her hoof against Fluttershy's back to try and rouse her, but it had no effect; Fluttershy's eyes were fixed firmly forwards, and she seemed to be having some difficult in catching her breath. Her wings continued to flutter, though they had slowed somewhat, and she still had her legs pressed together.

        “I'm so sorry. I let things go too far.” Twilight bit the inside of her cheek, uncaring even when the taste of blood filled her mouth, hoping to stave off another bout of lassitude that threatened to overwhelm her. All of those long talks they'd had, all of those promises to let things develop in their own time, all of those reassurances that they would take things nice and slow until they could well and truly call each other Special Someponies … all of that had been ruined. The notion that her sweet, innocent Fluttershy really was sweet and innocent had never once occurred to Twilight. Yes, she knew that the pegasus was inexperienced, but inexperienced?

        She'd never …

        Not once.

        Twilight felt sick; she'd robbed Fluttershy of something precious, something that she ought to have been able to discover on her own, not have it forced out of her by a stupid unicorn who couldn't read the signs that were right in front of her.

        Long, painful moments of silence – other than their strained breathing – ensued before Fluttershy finally stirred; she rolled on to her back, her wings wrapping protectively around her body. Twilight realised that she was doing what she did best: hiding herself away. Her hooves covered her face, and though she was still flushed and sweaty, mane clinging to her coat in thick rattails, her crying had at least diminished. Her tail continued to swish fitfully, as if trying to work out what to do with itself.

        “Fluttershy?” Twilight eventually asked, not really sure what the right thing to do was.

        “Hm?”

        “Are you … I mean, will you be okay?” Twilight, much as she yearned to, dared not approach the pegasus in her fragile state.

        Taking a deep breath that quickly turned into a yawn, Fluttershy said, “I … I think so. I feel really tired. Is that normal?” She looked up at Twilight with querying eyes.

        Her own eyes wet, Twilight nodded. “Yes, Fluttershy, that's perfectly normal after … what just happened. Why didn't you tell me that you'd never, um, had that sort of experience before?”

        “I was embarrassed,” Fluttershy replied, looking away. “You probably think I'm a total freak now, don't you?”

        “I do not!” Twilight finally traversed the short gap between them and slid her forelegs around the pegasus' waist. “I just wish you'd said something is all. You don't hate me?”

        “No, of course not,” said Fluttershy, returning the hug and feeling a little bit better now that she was in Twilight's hooves once more. “I just … I don't even know. I wish the circumstances had been a little bit different, that I'd had more time to prepare, but I suppose I'm grateful that it's just done and I now know what it feels like. I, um, I suppose I should be thanking you, shouldn't I?”

        “For what?”

        “Isn't that what you're supposed to do when somepony does something nice for you?”

        “What I did wasn't nice, it was … rude.”

        “Shush,” Fluttershy said, a weak smile forming on her lips. Pulling her weary body up a little bit higher, she placed a soft kiss on Twilight's horn.

        The unicorn shuddered, drawing in a sharp intake of breath.

        Fluttershy's eyes narrowed in confusion. “What was that about?”