Late Fees & Damaged Books.

"Come on, sleepyhead, you're a mess, and you and I have so much to do," came Twilight's unnecessarily cheerful voice.

Rainbow Dash murmured in sleepy protest, then as memories of last night filtered through, she jerked wide awake and she leapt straight at Twilight, bowling her over and pinning her to the ground.

"Twilight! You gotta help me! Something went wrong with the spell you cast yesterday and it's going to drive me crazy!" She frowned, "wait, how are you able to walk up here?"

Twilight raised an eyebrow. "The cloud-walking spell? Remember? We all came to cheer you on in Cloudsdale?" Her horn glowed and Rainbow felt herself yanked into the air as her friend got to her feet.

The magical grip floated her backwards out of the bathroom and over to her bed where it gently spread-eagled her and pressed her down into the bed.

"Uh, Twilight?" She struggled to get up, but while the lilac glow surrounding her didn't hurt, it was insistent on her remaining sprawled on the bed.

She looked over her shoulder as she felt the first tugs of a hairbrush being dragged through her tail.

"Twilight, thanks and all, but I really think you should stop."

Twilight sighed and stopped brushing. The magical force disappeared and Rainbow Dash got up a little unsteadily.

"I know you don't really want me to stop. I know about your little fantasies, and I know you're just waiting for someone to take charge." Twilight's tone was patient, but it had an edge to it that Rainbow had never heard before.

She laughed nervously, "now where did you get a crazy idea like tha-"

"You doodle in the margins of the books you borrow," snapped Twilight with the acid tone common to irked librarians everywhere. "Next time you want to draw filth I suggest an art class. And "mistress" is spelt with three S's, not two."

Rainbow Dash's eyes were wide and fearful, perched atop cheeks roughly the colour of beets. "Please, you can't tell anyone, I'd literally die of embarrassment!"

"Unlikely, but you don't need to worry about that, I'm not telling anyone. No, I have better plans for you, you book-vandalising little slut."

She frowned. "So, you're blackmailing me?"

Twilight laughed, "I don't have to blackmail you, Dash, I won't be making you do anything you don't secretly long to have done to you, or are you forgetting all the fun you had last night?"

"You did that on purpose?! I thought you just messed up that armour spell!"

"Do you need another demonstration?" Twilight's voice was sugary, and as her horn started to glow, Rainbow Dash backed away, protesting weakly before she felt a gentle but firm circular pressure on her clit.

"Haa, oh my gosh," she closed her eyes, then mumbled inaudibly.

"What was that, Dashie?"

"Don't stop."

She felt a swat to her rump. "Manners please, my little slut."

"Don't stop, please."

Twilight's voice turned sing-song as she kept up her slow, sweet torture, "I'm pretty sure you're missing a word there."

"Please don't stop, M-Mistress." Rainbow Dash's voice was as shaky as her legs at that stage.

"Better. Now lie down." Her horn glowed and Rainbow Dash felt herself being pushed gently onto the bed and laid out on her back. She felt a slim tendril of magical force slip up past her labia and swell inside her, filling her up and coaxing little moans from her. It twirled inside her, making her shudder at the sudden stimulation.

The magical intrusion quickly worked up a steady rhythm, making her legs rock back and forth with the motion.

Tendrils of magical force teased at her clitoral hood until the little pink button swelled, then a gentle squeeze as it was rolled and deftly massaged, which, combined with the insistent rhythm of the thick presence filling her up inside her marehood. It was almost too much to bear, her eyes rolled back in her head and her mouth gaped.

"I'm gonna-" Rainbow Dash's ecstatic moan was cut short by a whip crack and a searing line of fire right across the fleshiest part of her well-toned backside, and she gasped as the intensity of the fucking she was getting dialled down to a fraction of what it had been. "No no no no! Please, Twilight, you can't-! You have to-! I was so close-"

"I have to? I can't? Oh dear, is my little fuck toy telling me what to do?" There was the faintest hint of a growl in Twilight's voice as she clambered up on the bed. "I don't think you're getting it, Dashie, see, from now on, you don't get off unless I say so, you don't touch yourself unless I say so, and most importantly, you don't get anything until I'm a hundred percent satisfied. So, if you want to get more than just a taste, you'd better get your little slut mouth to work."

And with that dire pronouncement, she turned to straddle Rainbow Dash, lifted her tail and eased herself back until her hindquarters were barely inches from the flustered pegasus' face. She looked back over her shoulder and gave her a coy smile.

Dash blinked, still in shock, before a gentle magical pressure on the back of her head let her know that Twilight was not about to wait around. She pressed forward, the fuzziness in her head and the fire between her legs overriding any pretence of shyness she may have had. She licked, cautiously at first, then with greater enthusiasm as she saw how Twilight reacted to the touch. The folds were already slick with the purple mare's excitement before Dash even started, but even her inexperienced tongue soon had Twilight dripping and staining the blue fur of her chest.

Twilight pressed back against Rainbow's muzzle and let out an almost inaudible little moan that gave her the private little thrill of a job well done. She redoubled her efforts, focussing on working her tongue deeper inside Twilight's inviting slit. Before too long her efforts were rewarded with another moan of pleasure, and Rainbow Dash found her own pussy was tingling from the satisfaction she was getting out of hearing those little signs that Twilight was in ecstasy.

Twilight panted and pressed back so hard Rainbow Dash's muzzle was almost slipping inside her, her hindquarters quivering as she came. She relaxed, and let out a blissful little sigh.

"Mmmff?!" Her friend's voice was muffled, and the hot air tickled her between the legs.

"What? Oh, right." Twilight sat back up, and Rainbow gasped as her mouth was released from its warm, dripping prison.

"How was that, Twi-, uh, Mistress?"

"Not bad," came Twilight's cool response, only a slight shakiness in her voice betraying her studied nonchalance. "Now, clean me up, I have to go and see if Spike has finished his chores."

"You're leaving?" Rainbow Dash was crestfallen, the aching heat between her legs screaming its frustration in the back of her mind.

"I have places to be, and a long list of things to do. I'm afraid my new little fucktoy is just going to have to take care of herself until I come back."

Rainbow's face was the very picture of devastation, as Twilight hopped off the bed and started to make for the door.

"Please! I'll be your slave forever, just please don't leave me like this, mistress!" she pleaded, throwing herself after Twilight's retreating back.

"Is that so? Forever's a long time, you know." Twilight stopped and turned to face her. "That spell will wear off in about a month unless I undo it. You can't last one month without fondling yourself? You'd rather be my little pet forever?"

"It's not just that, it keeps playing with me, but it never lets me finish, and I can't stop it, and I swear I'll lose my mind if it goes on for another day, never mind another month! Please mistress, have mercy, I'll do anything!"

Twilight smiled a smile that was equal parts cruelty and compassion. "I have to go, but do a good job cleaning me off and I'll give you two minutes without the spell for you to try and finish up. Then take your time and make your decision. A month of torture, or a lifetime as my slave. I'll be back tonight for your answer."

Rainbow Dash nodded eagerly and got straight to work.