Celestia didn’t mind the mask. It made sure no one saw her eyes, and it dulled her senses. She didn’t have to see Shining’s surely ridiculous expression, could barely hear his obscene grunting, and it kept her quiet in her suffering.

The mask allowed her to be completely silent as she gracelessly swallowed more of his dick. Fellatio was a skill that she’d never been particularly gifted at, and Shining’s monster of a cock didn’t make the task easier.

While it was true that she was choking, and couldn’t breathe, the experience wasn’t wholly unpleasant. The mask kept her comfortable, and conscious. Also, somepony was gently nibbling at her and doing a thoroughly enthusiastic job, although Celestia feared it might be her sister.

Of course, it might also be Twilight.

She felt a shiver run through her spine at the possibility. Twilight had been growing quite handsomely since she’d ascended, and soon would be as big as Celestia. Perhaps even bigger.

Shining didn’t usually allow her to know who had been with her, instead leaving it up to her imagination. Once, Applejack had commented later that Celestia had been “mighty strong”, and she’d felt a rush of relief that it hadn’t been her sister and disappointment that it hadn’t been Twilight. Still, she’d asked Applejack to cuddle later, much to the congenial farm pony’s amusement. Applejack had been sturdy, and Celestia had enjoyed the happy post coital snuggling more than she’d ever admit to Shining.

Deep down in her soul she was still conflicted over her emotions. The worst part was that Shining had been completely right. The mares were nothing if not accommodating to each other’s needs, herself included. The only times she wore the mask on was when she was dealing with Shining, and though he certainly had a cruel streak he’d yet to deny it to her.

Perhaps one day she’d forgive him enough to fully face him, though she strongly doubted it would be before his demise. Shining had simultaneously given her everything she’d ever dreamed of, and taken so much more that she hadn’t considered. Needless to say, her emotions regarding him were complicated.

Celestia had long ago came to the realization that he was an absolute monster. Recently, she’d determined that he must not be the pony that had originally been “Shining”. He had to be some demon from some other world that was merely inhabiting Shining’s body and using his memories. He often spoke in a strange language, and knew things that went well beyond the powers of prophecy.

Sometimes she wondered what happened to the original Captain of the Royal Guard. She worried that this Shining had killed him, or consumed his soul or some such thing. Hopefully, at least, his soul had some sort of rest and wasn’t forced to watch this monster as it feasted on his wife, his sister, and the princess he’d sworn to protect. Cadence was pregnant, and Celestia feared for the foal, but she couldn’t fight against this Shining, her faithful student.

Not anymore.

He owned her and her sister now, and she’d compromised her morals originally just for the sake of her sister alone. She should have crushed him when she found out about his twisted habits. Maybe Nightmare Moon would have spared her, and she’d be living quietly chained up in Luna’s dungeon instead of ignobly choking on his dick several times a week.

At least it usually tasted like Twilight when she first licked it.

She shuddered again, feeling her wings spreading as he violently thrust down her throat. Unconscionably, she began to swallow and tease his length with her tongue. Some unbidden desire to please him still occasionally rose within, and she never truly fought it. If she was to be his sex slave, there was no reason she couldn’t be passable at it.

The shudder from remembering Twilight’s taste turned into a spark, and Celestia guiltily trembled. The pony between her legs noticed, and dug their snout deep into her. Celestia’s spark grew into a moist fire as her depths spread pleasantly wide.

She hoped it was Twilight. The mask had been tailored just for her to confuse her sense of identity, and it dulled all of her senses except for touch, making identifying the mare currently in her depths impossible.

Celestia slurped over his thick and throbbing cock, feeling it spasm and shake down her throat as the mask silenced her wet ‘glurk” noises. Shining slammed into her face with a heavy thrust, using his hooves to lock her snout firmly into his musky groin. A moment later, she gagged as a pulsing sensation down her throat informed her that Shining had finally cum. She waited as a warm glow filled her stomach, and slime oozed around his cock. He used a sigil to improve his stamina, his load, and his refractory period, so the amount of cum he drained directly into her stomach was always absurd. This time was no different

Whoever was behind her took advantage of her stillness, and Celestia tried to cry out around his throbbing dick. Their tongue lapped hungrily around her clit, and their lips pulled her wide apart for the rest of the harem to see. Celestia, too, now had a sigil of Twilight’s design on her inner thigh. Much like Luna’s, hers provided many boosts to her sexual capabilities. Unlike Luna’s, it didn’t prevent her from cumming.

Contrarily, it made the experience much easier to achieve and far more intense. Ever since Twilight had carefully burned it into her flesh, Celestia hadn’t been able to restrain herself once somepony started to touch her. She was learning to enjoy the inevitable throes of her now paralyzingly powerful orgasms.

She briefly wondered what had become of her decency and poise. Had Twilight taken it? Or had Shining? The thought made her even more wet, and she silently cursed as her body succumbed to the Sparkle sibling’s humiliation once more.

Her hips bucked, and she collapsed to the floor crying into the mask as she helplessly squirt over her mysterious benefactor. Tears built in her eyes and were banished instantly by the magic in the mask as she wordlessly choked from the unnatural bliss. She twitched around his softening cock, feeling it pull messily out of her mouth, the veins dragging across her softened tongue. She wanted to cough and throw up, but the mask didn’t let her.

Instead, she squirmed as her unrestrained fluids continued to drench the still hungrily licking pony behind her.

She knew Shining was manipulating her. She knew she was being trained to be his toy. Fuck, it felt so good.

Celestia let go of all her resistance under the mask, crying out her pleasure and weeping for her lost sense of identity all at the same time. A cage of euphoria held her hostage, keeping her from moving beyond autonomous kicking.

Shining’s voice sounded faint, dulled by the masks power. “I think it’s time to take off her mask.”

Panic filled her, nearly ruining her continuous orgasm. He couldn’t. Her face was still slick with his cum, the pony behind her wasn’t slowing or even stopping, and she couldn’t form a sentence or even a coherent action.

The light was blinding, and she coughed the moment the magically sedating mask was lifted. A huge glob of sticky white fluid was splattered on the ground, and the tears gathered in her eyes. Groaning, she looked up to see Shining staring down at her.

“Welcome back, Celestia. Did you enjoy your vacation?”

Celestia wordlessly nodded, only managing a guttural groan as she pressed her hips backwards into the searching lips buried under her tail. She was less than an animal, pawing helplessly at the ground as she stayed otherwise paralyzed from the sudden rush of sensations.

“Watch closely.” He smiled evilly.

Celestia blankly stared as Twilight stepped into her blurry, tear filled vision. Then Celestia saw Shining climb on top of the mare. They moved close, close enough that his dick, dangling limply underneath before it quickly hardened, and Twilight’s shimmering pussy was just in front of her face. She could smell them both. She could see them.

His cock mercilessly speared Twilight’s cunt, the throbbing member still slick with her saliva and white from his own seed. Twilight groaned, moaning in bliss as Shining plunged it into her, the white frothy saliva smearing all over her labia as he thoroughly hilted within her in one thrust. She watched his balls press tightly up against Twilight’s winking clit.

Celestia couldn’t look away, paralyzed by the automatic convulsions of her orgasm until Twilight’s gorgeous body was bucking back into Shining. Celestia’s tongue lolled in exhausted pain as she watched their tails entwine while she was forced to orgasm one more time.

Twilight moaned, and Celestia could feel the love in her voice. “Shining! I love you!”

Shining’s response was cruel, “Hell yeah you do! Fuck me, sis!”

Celestia blinked, tears forming in her eyes as she wordlessly groaned. “uh… h… oo…”

Twilight’s tail twitched wildly, and she began to buck upwards into her brother’s thrusts. Her response was focused, and devoted. “Yessss…”

Shining just grunted into Twilight’s hair as they kept fuckng, and he pressed into her hard. It had only been moments, but Twilight came just as hard, spraying her marecum backwards in an obscene and impressive jet.

“This is for you, Shining!” Twilight screamed as she came, without breaking her stride, or even pausing to catch her breath. Celestia swallowed hard, helplessly getting a few wet droplets on her face and blinking them out of her eyes. The smell of Twilight was overpowering.

Twilight really was thoroughly practiced.

Celestia groaned, cursing herself for the burning fire rising within her. Twilight was gorgeous, even being flaunted as Shining’s plaything. Celestia cried out, still riding the tail end of her previous release. The sigil’s magic flared through her, and she finally and willingly begged it to allow her another release.

She almost didn’t care when she glanced behind her and saw ethereal strands of midnight blue mane intermingled from under her own ethereal tail.

Almost.

Author's Note

Ehh, go for it. I'll just post what's left for this. Then I don't have to change the tag.