Starlight shivered as she stared at the odd oval hole in space. “That’s strange… I can’t see anything, but I just felt the magic in the room increase dramatically…”

There was nothing there but a strange pink and red haze.

“Maybe you should shut it off. I can’t make out anything.” Trixie muttered as she squinted from the couch. “Still, even I feel something weird.”

“Yeah, I suppose I should—ah!”

“Starlight?”

“Oh, just… another magic surge and—OH!”

Starlight squealed as something far stronger than a magic surge hit her. Her body thrummed with energy and power as something she couldn’t see slipped up behind her.

Starlight froze, her mouth hanging open, unable to speak a single word as she felt two delicate hands wrap themselves around her body, caressing and teasing with impossible precision.

A voice in her ear whispered words and they slipped out of Starlight’s mouth without her mind being involved at all.

“Oh, sorry, Trix,” the invisible creature said through her. “Just a spike in the ambient magic. It’s sorta getting to me. Give me a minute.”

What are you? Starlight demanded as the hands teased her nipples and continued to roam over her body, somehow knowing her favorite spots.

Not what, darling, cooed the voice.

Rarity? Starlight asked in shock.

Starlight shivered again when she felt a warm hardness slid between her ass cheeks.

Not the Rarity you know, my pretty thing. The voice continued in tones that made it impossible not to imagine a very horny and very naked Rarity standing there with her. Somepony far more sensual, beautiful and erotic. Somepony who’s enjoyed more sex than you can imagine. Somepony… who’s going to share that hot little body of yours for a bit…

No, I… I…

Starlight tried to find words—mental or physical—but nothing came to her as the being pressed into her. She shivered as the creature’s hand touched her pussy, sending a shock through her body that made her open up her backdoor purely by instinct.

That’s a good little slut.

“Starlight? Why haven’t you shut it down yet?”

“Trixie… you should… should go to…” Starlight tried to get out, but the thing calling itself Rarity overrode her. “Go to the bedroom for a toy or two, Trix. I’m going to give you a little show as a reward for helping me today.”

How can you know she was helping me? Starlight demanded.

Because, we’re already becoming one, darling! I know every sexy encounter you’ve had with that tasty little morsel, including the weekend where the two of you roleplayed as Sunburst’s little fuck maids. That was fun, wasn’t it?

Starlight would have paled if she could have.

Yes, you remember that perfectly. Taste a little of it…

In a second, she could feel Sunburst’s cock on her tongue. She could smell him and the scent of the wild Trixie on the other side of the cock. Any second, their tongues would meet and—

“Really?” Trixie squeaked in surprise. “Any toy?”

She will be next, Rarity giggled. Though I’m grateful you’ve managed to become lovers with this one. She only drops the third-person with her lovers and I find ‘Trixie this’ and ‘Trixie that’ so very tiresome.

No, I won’t let you do anything to my girlfriend!

Who said anything about me? Rarity laughed.You’re going to corrupt her. Just like you’re about to be corrupted yourself. Bend over a bit, darling… that’s it. A bit more, like the good little slut you are.

“Really, Trix,” Rarity said with Starlight’s lips. “I’ve got something special in mind.”

“What about our costumes?”

“Oh, that’s part of it. Trust me.”

Starlight had almost no control over her body as she bent over to present herself to her invisible attacker. She needed to cast something or do something but…

She tried a protection spell. Rarity corrupted it instantly, transforming it into a spell that slowly teased Starlight’s tits while leaving her unable to react.

“You’re sure?” Trixie sounded giddy. “Can we use the… big one?”

“Yes, Trix,” Starlight’s mouth said. “I’ve actually been thinking of it nonstop all day.”

Trixie squealed in delight and galloped out of the room.

You—

No more protests. Time to try this body on for size…

Starlight nearly screamed when the cock slid into her ass, but a moment later, her body transformed to adapt to the invisible intruder. Starlight moaned softly as she felt herself being reconfigured, her ass changing faster than it should have, changing so Rarity’s cock fit inside her perfectly. Starlight’s tail twitched back and forth as pleasure overwhelmed her mind.

That’s it, darling. You’re an eager thing, aren’t you? Happy to share…

“Share…” Starlight murmured as Rarity thrust three times. “Yes… I… no, shouldn’t share… need to… give in and be the slut Rarity wants me to be.”

That’s it. You’re doing wonderful. Time for some adjustments… Rarity cooed. You’re going to end up so sultry. Almost as much as my Starlight…

Then Rarity slammed forward, her cock rushing into Starlight’s ass and hilting… only for the movement to continue through Starlight’s crotch as a thick physical cock swelled into existence above her pussy.

“What… what’s happening…” Starlight whispered as the new cock tented her panties and capris. “Why… why do I have a dick…?”

Why, you need both, darling. How else are you going to seduce and corrupt everypony you care about, male or female?

Rarity didn’t let Starlight get in another word. Instead, she let her demonic pleasure tool grow on Starlight’s body. Starlight was so shocked by the appearance of the cock, she didn’t notice the swelling of her hips and breasts. Rarity, meanwhile, slid into the unicorn mare as if she were slipping into a pool of water. She reached into Starlight’s mind and—

Only then did Starlight realize she was thinking from Rarity’s perspective. The creature… it was, it was…

Rarity moaned in delight using Starlight’s mouth as she suffused the mare with her essence, melting into the increasingly-horny mare. Her lust-fueled, carnal thoughts wrapped around Starlight’s, corrupting them in short order as the new cock grew. With a wave of Starlight’s magic, Rarity destroyed every stitch of clothing below Starlight’s waist, leaving her only in a frilly top that was creaking at the seams. She reached down to stroke the tool and Starlight shivered.

“I’m possessing you, Starlight Glimmer,” Rarity said in Starlight’s voice. “Your body and mind are now mine, corrupted by my Queen’s lust and power. Tell me what you think of your new existence.”

Starlight’s tits swelled a little more and her top just came apart into shreds, leaving the mare naked with a new tool.

“I… I… shouldn’t like this…” the original Starlight whispered with a shudder, obviously trying to fight it. “But…”

Rarity stroked Starlight’s new horsecock a few times, feeling the cum churning in her balls.

“Ohh!” Starlight cried. “Don’t… don’t stop…”

“Then look at yourself, pet,” Rarity whispered. With a thought, she took control of Starlight’s magic. The mare moaned, her hips bucking as Rarity demonstrated her perfect control over Starlight’s body. “Look hard.”

And Rarity conjured a mirror with Starlight’s magic.

Starlight—and Rarity—stared at the body the both inhabited. Slowly, Rarity’s sultry and horny smile overwrote Starlight’s shock. Starlight’s mane had grown, now going nearly to her tail. Her eyes glowed with a faint pink light. Her lips were thicker, too…

Rarity forced Starlight to speak her thoughts on her new appearance out loud.

“Cock… cock sucking lips…” Starlight whispered.

Rarity shivered in delight and then, in Starlight’s voice and with Starlight’s cock-sucking lips, said, “I love to suck cock.”

Starlight shivered as lust consumed a little more of her self-control.

The next improvement was Starlight’s tits. At least double what they had been with far larger nipples, they were tiny compared to the Council of Lust’s, but Starlight wasn’t ready for the full blessing yet.

“My tits are huge…” Starlight said. “Enormous…”

“Perfect for feeding hot mares and cute stallions, for shoving thick cocks between and for showing off just how slutty I am,” Rarity added helpfully.

Starlight was so grateful she had Rarity to guide her into becoming the mare she had always wanted to—

No, that’s not… not me…

It is, pet. Now it is. Soon, you’ll love your body and be desperate to share…

“No…” Starlight said with almost no conviction.

Her taught stomach led to flared foal-bearing hips, a wet sex with her little bit of hair now replaced by the heart-shaped crest of the Council of Lusts. Starlight brushed it and moaned instantly as a tiny false orgasm crashed through her, forcing her to give voice to her lusts.

“I love this body!” Starlight squealed, then clapped her hands over her muzzle.

“You can only speak the truth when you touch the Seal, pet,” Rarity replied. “You do love it!”

There was the thick purple cock, the enormous balls waiting to be unloaded, and the perfect slim legs leading down to dainty feet.

“Well, I know you love your new body, but what to do with it…”

“Maybe get you out of me!”

“You want me out?” Rarity giggled as she dismissed the mirror. “Then cum on that little wind-vine you got from the Everfree. Do it, and I will show you magic you’ve never seen, my eager little slut. Maybe you can turn it against me somewhere”

Rarity had slipped almost entirely into Starlight. Starlight sensed her body churning under the spirit’s power. And… she wanted it. Or was it they?

There’s not much difference anymore, is there, slut?

No, Starlight replied woozily. There’s… I’m…

Cum on the plant, my little pet slut, Rarity instructed sweetly.

Starlight’s body stumbled forward, then dropped to her knees. Rarity moaned as she became more and more with this silly and weak Starlight.

“I am silly and weak,” Starlight mumbled as Rarity commanded her to jerk off on the wind-vine. It was getting harder to think by the second. Harder to think anything but Rarity’s twisted thoughts. “I… I need to be possessed… corrupted.”

“Good girl,” Rarity cooed in Starlight’s voice, licking her lips. “Now, cum for us and feel it for the first time.”

Starlight’s body instantly started to cum as Rarity enjoyed the familiar sensation. It was… familiar to Starlight too, now. She… she’d cum from her cock many times before. Hadn’t she? Every spasm felt right and good and… yes.

Yes. This was right. She’d… she’s always been like this. She’d always been blessed with both. All of her lovers had embraced it, Trixie most of all.

Hadn’t they?

Yes.

Starlight couldn’t tell if she had thought that or if… was somepony in her body with her? That seemed… odd…

As she thought, she stared at her spasming cock as it coated the wind-vine with her seed. The wind-vine began to twitch and shift.

Here’s how this works, Rarity said conversationally. I corrupt you into a slut as horny and debased as I am while we exist as one. After you've turned, you get to turn others! After a time, I go home… you—and everypony else—stay a slut. Then you keep helping others. When the time is right, you open that portal again and step through. Only then will you be made fully complete just as you’ve always wanted.

“Always wanted…” Starlight echoed, feeling so wonderfully empty.

That’s a good slutty pet.

Starlight couldn’t stop herself from stroking her still-spasming cock even as her tits swelled to the point where they threatened to topple her. Which was good. Sluts should be stacked and naked. She was a slut now. Rarity had been one. Rarity and Starlight were the same now. So, now she was a slut. She smiled faintly, happy that she was able to figure that out through the haze.

“What… what is the plant going to do?” Starlight whispered as Rarity moved the twitching wind-vine to the doorway Trixie had disappeared through.

“Make Trixie feel as good as you do now,” Rarity said, this time in Starlight’s voice. “She deserves it. She deserves to be as much of a slut as I am and you are.”

“Yes… she does,” Starlight whispered as she looked up at the doorway where her girlfriend—and soon to be fuckbuddy—waited to be turned into a slutty thing like her.

Author's Note

I totes love this part. The (sorta) slow and wonderful corruption of Starlight into Rarity's little sex toy~! I mean, who wouldn't be happier like that~?

Lemme know about errors and stuff by PM~! :3