The guard pulled back the bolts, multiple layers of metal and stone clicking and whirring as clockwork locks disengaged and magical seals grounded themselves with a crackle of energy. "Please enter, Miss Cheerilee. Signal if you wish to stay longer than one hour. You will be extracted if you reach two. Good luck."

"Thank you," Cheerilee replied, a tremor of nervousness in her voice. The vastly heavy, reinforced door swung out a few feet, letting her slip around the edge of it, then swung closed again, trapping her in a narrow, hotly airless chamber. Mechanisms ticked and clattered within the walls as gears turned behind massive stone blocks. Cheerilee tugged at the hem of her burgundy skirt. Her jacket matched the skirt, each a slightly darker shade than her own skin, over a black blouse. Dark stockings and neat black heels completed her look.

It wasn't the first time she'd made this trip; not even close to it. But each time, it made her heart hammer in her chest, her limbs weak, her breath short; stolen from her by scarcely-controlled fear and anxiety. And, of late, something else, too.

The inner door slowly ground open. Cheerilee straightened her spine, and stepped into the chamber.

"Good afternoon," she greeted the mare within.

The pony that once had been Celestia lay sprawled across her lavish, fanciful bed, stark naked, heavy breasts and bare sex on full display. Heatless fire cascaded from her head and flowed from the spot above her soft, round ass, giving her the impression of lying amidst a pool of flame. Slit pupils regarded Cheerilee with lazy amusement. "Back again?"

Cheerilee took a slow, controlled breath, trying to pretend her body wasn't automatically, instinctively reacting to the incredible body of the nude demigoddess. Months ago, she could hardly have imagined she'd ever be in a position to see such a sight, but Twilight had come to her and asked for her help. Meetings between Daybreaker and Twilight always went badly; it was too easy to push Twilight's buttons. Luna could barely force herself to enter the cell at all, and those encounters always fell apart into screaming matches. What was needed was someone Daybreaker didn't really know at all. An outsider. Somepony that wasn't disorientated by the anti-magic warding that permeated the cell. Somepony to find a way of reaching out to a troubled pony, and connect with them.

"Sit up, Celestia. We're going to go over the material again," she declared.

Daybreaker's nose wrinkled in annoyance and she rolled onto her side, presenting her back and her wide, shapely ass.

"Celestia!" snapped Cheerilee sternly.

"That isn't my name," huffed the naked mare without turning around, ruffling her wings in annoyance. She paused, and then added in a smugly sibilant tone, "If you want my attention, you're going to have to give me something to look at..."

Once, a demand like that had floored Cheerilee in shock; she'd demanded to know what Daybreaker meant, and as the captive mare's crude insistence had grown louder and more lasciviously detailed, she'd panicked and signalled to leave.

They were long past that stage.

The sound of the zip was clearly audible in the stone-walled chamber. Her skirt fell smoothly to the floor, crumpling into a puddle of fabric around her heels. Her intricate, lacy black underwear clung to the subtle curves of her sex. Cheerilee took a deep breath, feeling a pleasant shudder run through her.

"Pay attention, student," she commanded firmly.

Daybreaker turned her head back, then grinned, baring her fangs. "Very nice... New. Expensive. You bought them for me, didn't you. Teacher." The corrupted pony had a way of saying 'teacher' that was worth a thousand husky, lustful promises from any other mouth.

Cheerilee ran a hand over the curves of her chest, feeling the heat of her own skin through the thin blouse, before letting her fingers trail down to her waist to lightly cover her sex. "Do as you're told," she commanded, infusing her voice with all the practised authority that came from years of disciplining unruly students. "Sit up."

Slowly, languidly, Daybreaker unfolded her long limbs and swung her legs off the bed, sitting on the side of it. Planting one hand behind her neck and arching her back, she thrust out her breasts, her eyes lidded and only half-open. "Yess, Miss Cheerilee," she purred. "Going to adopt the teaching position?"

Like every impertinent, too-accurate question from Daybreaker, that one was best ignored. Cheerilee strode forward, her heels clacking on the floor, trying to pretend that her own body wasn't already simmering with arousal. In one smooth movement, she straddled Daybreaker's lap, feeling the heat of the other mare's smooth skin pressing against her thighs. The other mare was taller than her; despite sitting atop the corrupt alicorn's legs, she found herself gazing into Daybreaker's half-familiar face.

"Let's begin," the teacher breathed. With convulsive need, Cheerilee seized hold of Daybreaker's vast breasts, squeezing firmly. Her fingers sank into the soft flesh, kneading and crushing them together, and a fiery burst of hot arousal sparked through her own body as Daybreaker gasped, eyes closing and lips parting. "What is your name?" she demanded.

"Daybreaker!" hissed the other mare, then gasped as Cheerilee twisted her tender pink nipples, pinching firmly.

"Wrong! You know what the answer is, and you will give it to me," commanded Cheerilee, feeling a glorious tremor of lust shiver through her at her own roughness, her own brutality. Her hand cracked against Daybreaker's bare breasts several times, marking the flawless white skin with red handprints.

"Rrr! Celestia! Celestia," Daybreaker growled, then whimpered as Cheerilee's hips rocked, the teacher's dextrous fingers stroking and toying with her taut nipples again. "That's what you want to hear, isn't it?"

"Say it. 'My name is Celestia'. Again! I'll make you write it with your tongue on my pussy if I have to."

"My name is Celestia," groaned the captive mare, and her moans suddenly rose in pitch as Cheerilee shifted to straddle one thigh and let her knee grind against the naked pony's sex. "My name is Celestia, my name is Celestia, rrrrmm, my name is Celestia," she panted, her head tilting back.

Cheerilee let go of Daybreaker's breasts, prompting a growl of disappointment that was almost a snarl, before planting her hands against her own chest. "Answer this correctly, and I'll open my blouse," she announced, in a stern, no-nonsense tone that was hopelessly belied by the way she kept grinding her cunt against Daybreaker's thigh. "What is your duty?"

"Do whatever I like!" snapped Daybreaker.

"You know the correct answer, Celestia, and I will walk out that door if you don't give it. Answer me!" Cheerilee panted, not even sure herself whether she was bluffing or not.

Those slit-pupil eyes stared into Cheerilee's, hot and burning yellow, before Daybreaker smiled with poisonous sweetness, and purred in a sing-song voice, "Protect all the helpless little ponies of Equestria. Now fuck me."

Cheerilee reached for her top button, then gasped as Daybreaker impatiently swatted her hands aside and grabbed both sides of the blouse. A sharp yank, and her buttons flew across the bed, baring her bra-clad breasts; a second sharp tug upwards pulled her bra out of place, spilling free her bare tits.

"Mmmh, yes, yes, teacher. Nice tits. Your student can't get enough of them," Daybreaker teased huskily, capturing them in both hands, then lifting them to let her slender tongue play over Cheerilee's dark maroon nipples.

"That's right, Celestia. You can't," agreed Cheerilee breathily, her head tilting backwards as the former Princess eagerly suckled on her breasts. "I can - mmmh! I can hear the sincerity creeping into your voice, day by day, even if you can't. You know that's your real name. You know you care."

Daybreaker lifted her head sharply, her pupils shrinking to vertical slits as she retorted, "I don't, and it isn't."

Cheerilee's hand cracked against her breast again, and Daybreaker shuddered. A keening moan escaped her as the smaller pony began rocking back and forth atop her thigh again, her knee rubbing firmly against Daybreaker's dripping cunt. "You're lying, Celestia. To me, and to yourself. We're going to fix this. You're going to get better. You're getting better. And when you admit to yourself that you want to be helped, we can fix what you've done to yourself."

For a half-second, Cheerilee thought she saw a flicker of yearning cross Daybreaker's face that owed nothing to arousal. Then it was overtaken by another sharp shudder of arousal, and the blackly amused expression curled Daybreaker's lips once more. "All you're doing is giving me a hot mare to fuck to while away the hours, teacher."

Cheerilee grabbed Daybreaker's shoulders, and threw herself forward, shoving the larger mare flat onto her back. As Daybreaker growled with amused arousal, Cheerilee crawled up her body on all fours, blouse dangling loose, and turned around to straddle the other mare's face. "Eat my pussy, Celestia. The way you've been taught. And if you fail me this time, you will wish you hadn't."

Flexing her thighs, Cheerilee sank down onto Daybreaker's mouth, feeling her long, hot tongue push aside the feeble barrier of her drenched panties and begin lapping urgently, hungrily at her folds. The pattern in her licks was distinctive, recognisable; over and over, Daybreaker spelled out, 'I want to get better'.

Filling her hands with Daybreaker's soft, jiggling tits, grinding her cunt all over her former Princess's face, Cheerilee gave herself over to pleasure.

"Time's up," murmured Daybreaker, with an exaggerated pout. "You could just tell them you want to stay here. With me."

Cheerilee shook her head, tucking her blouse into her skirt and neatening herself as best she could. It was going to be hard to hide the damage to her clothes, but she could always explain it away as some kind of brief fight. "I will return tomorrow, Celestia. I think we're really making progress."

"I agree," purred Daybreaker, with a fanged smile. The inner door began to grind open, and the corrupted alicorn leaned forward, her voice suddenly husky and urgent. "You want this. You don't want her back. You want to keep fucking me." Her tongue flickered over her lips. "Let me out. It would be easy. You will have a place in my court, my favourite concubine. You will sleep in my bed, and be tended to by every pony you wish. We will fuck in ways I've never offered to you before. Do it. Be with me."

The door ground to a stop, half-open.

Cheerilee shook her head. "I'll see you tomorrow, Daybr- Celestia."

Cursing herself for the slip, she didn't wait to see the expression on the other mare's face; she stepped into the lock chamber and held herself tensely until the inner door shut behind her. It wasn't the first time Daybreaker had offered her something of the sort.

It wasn't the first time she'd been tempted by the glorious, sensual, impossibly enticing mare.

Every word she'd said to Daybreaker - to Celestia - was true. Little by little, she was getting through to the Princess she'd once been, she knew it. It was easier and easier to get her to speak her true name, there was a truth in her vow of protection, even if she still had to be forced to say it. Sooner or later, there was going to be a breakthrough, and the cell would no longer be necessary.

Yes. Sooner or later, one of them was going to give in.

She just couldn't be certain it wasn't going to be her.

Author's Note

For this week, I made use of a prompt generator that I wrote in Excel, mixing and matching ponies together and suggesting a fetish or two on top. Chapter 1's encounter between Celestia and Sunset came about because I misread a generated prompt that actually read Cadance and Sunset, and decided I liked it more. While I didn't let it dictate what I chose to do - I discarded many more prompts than I accepted - I did find it useful to produce less common pairings. Cheerilee and Daybreaker was one such pair that I probably wouldn't have thought to combine otherwise.

• Proofing by Djmill and JustTheBast
  Suggestions by DbzOrDie