Late Fees & Damaged Books.

Rainbow Dash's wings unfurled with a whump noise as the air caught her and pulled her safely out of her dive. She glided upwards gracefully for a fraction of a second before landing. She grinned to herself with the satisfaction of a perfectly executed landing, and gave herself a moment to stretch before knocking on the door to Twilight's library treehouse.

"Hey, Twilight, I'm here, so let's get this over with, okay?" She called out, and when she got no response, pushed against the thick wooden door. It had been left unlocked, which she took as an invitation to come in and make herself at home.

"Hellooo, Twilight! I haven't got all day here." Rainbow's patience was wearing thin, and being called here on some barely explained pretext was inconvenient enough without being kept waiting as well.

"Ah, great, you're here," gushed Twilight, popping her head over the rim of her second floor bedroom. "Just take a seat, I'll be right there, okay?"

"Yeah, fine, whatever." Rainbow sighed and flopped unceremoniously down on a couch of the sort favoured by Rarity.

She clopped her hooves together idly as sounds of an extremely bookish nature filtered through from the mezzanine. They didn't sound like her sort of books either, these sounded distinctly like the sort of monolithic grimoires that her friend devoured with glee.

She sighed again, louder this time, hoping that some sign of her irritation would filter through to Twilight and get her to hurry up with whatever she wanted her for.
Rainbow Dash felt hot, uncomfortable, and inexplicably itchy, and the waiting was doing nothing to improve her mood.

"Come ooon, Twilight! Get a move on!" She whined.
"Coming!"
"Yeah, well, so's Winter Wrap Up." She muttered under her breath. She reached down and surreptitiously scratched the itch that had been building around her crotch, and recoiled when her hoof came up slick with her own juices.

"What in the...?" She furrowed her brow. She took a quick peek between her hindquarters and found that it was no mere itch, she was dripping wet down there, and she had no idea why.

"Hey, Twilight?" She called out hesitantly, "mind if I use the facilities? I'm... uh... kinda dirty from the landing."

There was no answer but the sound of riffling pages and the occasional thump of a book hitting the floor. Rainbow Dash decided that this was as close to a yes as she was going to get. Hurriedly, she scrambled off the couch and barrelled down the hallway to where the bathroom was.

Locking the door behind her, she sat down on her haunches and prodded gingerly at the damp matted fur between her hind legs. She cursed silently to herself. It had even gotten on her tail. It was the strangest thing, her pussy was tingling and gaped open slightly, just as if she'd been... She blushed, angry at herself. She must have gotten carried away daydreaming or something.

She froze as she heard the door open. She was sure she had locked the door, hadn't she?
She looked round, guilt written all over her face.

"Oh, Rainbow, look at you, you're all wet, let's get you cleaned up." Twilight smiled, and levitated a small fluffy towel. She dabbed at the inside of Rainbow's thighs where drips of moisture had dribbled down, while the mortified girl stood transfixed. The towel rubbed ever so gently upwards along the arch of her hind legs until it reached the apex, where Rainbow gave an involuntary groan as her legs trembled. She bit her lip, humiliated, but her friend only smiled.

She turned and trotted back out into the main hall and called back, "Let's get started, okay? This is kind of a tricky spell, but I think you'll like it!"

Dash shook her head, trying to dislodge some of the fog of arousal that was clouding her thoughts, and then followed Twilight.

Throughout the next few hours she began to wonder if she'd just imagined how strangely her friend had been acting, and focused instead on the invisible armour spell Twilight was testing out. She'd been right in thinking the spell would appeal to Rainbow Dash's headstrong nature, as the spell created a magical barrier that repelled anything that came close, and even stopped her hurting herself when she fell. She grinned to herself, thinking of the stunts she'd be able to pull off now that she wouldn't have to worry about breaking a wing.

The feeling of invincibility only subsided midway through the flight home as she felt herself start to tingle again. She pulled up into a hover, and sure enough she was mysteriously dripping wet again.
"Oh come on, you've gotta be kidding me!"
She took off at top speed, the last thing she needed right now was to run into anyone while she was like this. She blinked back tears as the wind whipped past her and before she knew it she was back in her own little castle in the clouds.

The tingling was almost unbearable by now, but now that she was home she was looking forward to dealing with her little predicament. She felt something drip down her thigh and caught sight of the stained and slick fur running all down her hind legs.

"Heh, I could probably do with a bath too." She reached down between her legs and frowned. She couldn't feel anything. She inspected her hoof, but couldn't find any signs that it had made contact. "Weird," she muttered.

She trotted over to one of the larger mirrors in her bathroom and craned her neck around to see. She prodded gingerly at herself, but again, she couldn't feel anything other than the heat radiating from her behind. She prodded again, more forcefully, but her hoof seemed to glide off at a tangent without ever getting closer than a few millimetres.

Her eyes went wide with sudden realisation, Twilight's armour spell. She must have forgotten to remove the shielding from everywhere on her body. She would have to fly back and get her to disable the rest of it. She cursed under her breath, she knew too well that she wouldn't be able to fly with this distraction.

She felt a sinking feeling in her stomach as the heat between her legs intensified and her whole body gave a little shudder that started right at her swollen, aching clitoris and swept all the way down her legs and up to the very tips of her wings. Her tail had lifted invitingly, a reflexive response to her mental state.

Her hind legs buckled and her rump slid inelegantly to the fluffy surface. It tickled ever so slightly, and almost before she realised what she was doing she had started to scoot her rear end along the floor. Her little breathy moans gave way to sobs of frustration, as the little tendrils of cloud just weren't quite enough to send her over the edge of the orgasm that just wouldn't come.

She felt then, just as she thought she would go mad, the slightest sensation on her nether lips, as though some force nipped at them, rubbed along them teased them apart, spreading them. Rainbow Dash shut her eyes tight and bit her lip in concentration. She was being offered salvation and she was damned if she'd let this sensation go to waste. The force tugged ever so slightly at the top of her slit, and obediently she raised her ass on legs that quivered and shook in tension, following the sensation upwards. She was rewarded when a slim tendril slipped inside her, and she knew that even if she had wanted to stop it there would have been no point resisting. It squirmed and wriggled inside her until, with a gasp and a shudder, it had found the spot it was looking for. She felt powerless, puppet-like, but this presence knew just what it was doing, and after what seemed an eternity of gentle massaging and rubbing, she buried her face in the cloud and screamed as waves of ecstasy racked her body, sending heat and pure unbridled pleasure through every nerve.

Her hind legs finally gave out and she flopped to the floor in a haze of post-orgasmic bliss. A dopey smile spread across her features as she curled up and fell asleep right there on her bathroom floor.