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Rarity receives a strange visitor who needs help with her bra fitting. Rarity is shocked at Sunset's new and enhanced dimensions, but maybe she should focus less on tits and try to keep a clear mind. 
At any rate, Sunset can help by washing it deep and clean for Rarity's own sake...
And their new Mistress, of course.
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>Rarity always had an eye for details
>She was the first to notice Sunset's new, strange behavior
>She was probably among the first ones to also cum herself to sleep over her transformed friend
>She has managed to maintain her facade though. Nobody can see past her poker face
>At least until now
"Welcome to Carousel Boutique, Darling! I will be there in... a... jiffy..."
>Rarity's words trail to an excited hiss as her eyes connect to her brain
>The person who just stepped inside her Boutique (actually more like a shack she rented for a few bits and that she's pretending is some high-brow atelier but hey, you gotta start somewhere) is not here for business
>At least Rarity's pussy really really really hopes she isn't
>Because under her skirt she is not wearing panties today
>And dripping her juices down her legs is quite unbecoming of a lady
>"Hey Rares," says Sunset Shimmer
>She's just... standing there, deliciously
>She opted for high-heels leather boots that stop midway to her knees, displaying her long, smooth legs all the way up to her tiny, black/bronze skirt, painted-over her sinfully thick hips
>She is wearing just a leather jacket
>A short leather jacket
>Not padded. Her nips protrude like little bolts atop bolt-ons
>The kind of jacket that shows off her studded belly and trim abs, and stops just below her inflated, rounded boobs
>Rarity has to remind herself she is a lady and ladies do not drool
>Not even when a certain Sunset Shimmer cups her enormous tits with a grin and a sexy glint in her aqua eyes that send said lady's nethers into overdrive
"Sun! Set," 
>Rarity greets her in a fairly high-pitched and mysteriously nervous voice. 
"What a surprise."
"Yeah 'set'. You can say that... twice," her busty friend replies.
>She draws her tongue over her lips. There is a new piercing in its middle.
>Rarity's pussy whispers to her brain how it would feel to have that studded tongue play with her very needy and very hard clit and she forgets what's happening for a few seconds
"You okay Rares?"
"NEvEr BEttEr" 
>She says with a strange stress over the wovels.
>It almost sounds like she's out of breath
>Weird behaviour for a lady
>She decides to take a seat and not go to greet her friend. Quite rude but so would be leaving a trail of pussy juice over the floor and she just got it cleaned
>Safety first
"WhAt cAn I dO foOr yOu... SUnsEt," she asks with a strained smile.
>She probably sounds like she just gulped two pounds of helium
>It's note like she can check though, her words sound distant and faint over the thunderous echoes of her heartbeat
"Oh nothing much," she looks shy and uncertain for a moment.
>Scratching her back of her neck and looking away, she reminds Rarity of the old Sunset Shimmer
>She's changed so much. She walks up to her and sits down next to Rarity.
>Her inflated tits wobble slightly, less than if they were, you know, real
"I kind of need a bra fitting."
>The words rattle inside Rarity's brain
>There's suddenly a lot of space there
>Without waiting for an answer, Sunset pouts and cups her huge tits. Her fingers have to spread just to cover half of her spherical jugs
"These things are heavy as they are. And they are still settling in, so I need an expert's opinion," she winks.
"ExpErt." Rarity grins.
>It's the most her brain can do right now
"Yeah! You get it Rares. I can trust you not to get too... excited by my inflated dimensions. You know."
"Of c-course! No e-excitement here, Darling! I'm a professional!"
"Right! You are the best for this job."
>Rarity nods so hard it's kind of a miracle her grinning head does not fall over her chest and rolls against the wall
"I'm glad you understand, also because..." she trails off.
>Rarity crosses her legs. It's just a habit, nothing suspicious here. No need to focus on that or the musky scent that is starting to spread from under her seat
"...I have been thinking of going bigger."
>Rarity blinks. While her ears are busy trying to understand how seven words could break her mind so thoroughly, her brain floats towards horny jail
"I mean I know you don't get embarrassed over such things, haha!" Sunset pulls her back. "You're one of my best friends!"
"Of course I am! Dear, you know you can always come here and talk to me about... your... breasts...! And their shape and size and... whatever you wish, really! I'm yours Darling! I mean, at your service."
"That's so sweet of you Rares, I knew you'd understand." 
>She huffs and stretches.
>Her chest pushes forward
>It looks about to pop
>Not as much as Rarity's eyeballs though
"You know what, Rares?"
>Once again she does not wait for Rarity's cells to keep pumpin ATP into her brain
"I never thought I'd get my tits done. Just... one day the idea, like, popped right into my mind!"
>Her eyes turn dull and glassy just for a moment. It's quick, but it does happen
>Rarity does notice
>Her pussy writes it down for future reference
"And do you know what's the best thing about being a slut with big fake tits Rares?"
"What... what it is, Sunset?"
>All the while Rarity's inner voice is going "Tell me, tell me, TELL ME!", but she's a lady and does not show it
"I completely lost people's respect!"
>If Rarity's pussy grows even a few degrees hotter she might start melting her chair
"They look at me and they only see a fuckhole! It's perfect! They know I love to lay on my back and take dick for hours and I got these tits for attention and to be treated like an object! Can you guess how many people wanted to listen to what I had to say ever since I upgraded?"
>Rarity nods
"Zero! Absolutely none! Nobody wants to listen to me, they all just want to fuck me or motorboat my tits. And I don't mind. I mean, I'm just a set of holes. Having a conversation would kinda go against the point, hm?"
"Yes! I completely agree, Darling!"
>She beams. She's such a proud slut
"I knew you would get it. Now... what about that fitting?"
>Sunset's fingers cup her breasts
>This time they reach for her zipper
>She pulls it down. Slowly. Rarity's ears savor the zipper as it softly crackles
>With each inch she reveals acres of smooth, orange flesh
>Her skin is strangely taut and has a curious sheen
>Really shows how new her tits are
>The tits that will forever mark her as a slut
"I... see," Rarity manages to say, though her tongue is really dry
>Sunset stops halfway through. Her tits rest held by a lacy black bra, her nipples holding back the leather
"I actually don't know how big I am right now. Would you mind?"
"At once darling. Can you pass me the tape?"
>Sunset complies. Thanks to some merciful god, Rarity left it at hand's reach and she does not have to stand up and show the puddle of juices she's leaving on her chair
"Thanks darling. Now..."
>She starts by measuring her torso. She frowns.
"Uh... 28 inches? You used to be at least 30."
"Ah, that's because I went so big right away. My bra needs more room and it sets a bit lower on the ribcage. It tends to lose a couple inches."
>She got her tits so big her bra has to get extra support to cover them
>Rarity squirms. She needs a long, hot shower
>Maybe three
"M-Makes sense."
>She's so close she can feel the heat from Sunset's chest
>Leather creaking with each of her breath
>She could just grope them
>Feel a slut's tits
>Sunset would love it
>But she's a professional
"So now about the... huh... bust."
>Her hands did not tremble like since she was 6 and had just found out about needles
>She slowly moves the tape to cover her chest from side to side
>As her fingers brush against Sunset's nipple she lets out a sharp moan
"Sorry, sorry! Kinda sensitive around there."
>Rarity smiles and tries to remains focused. She is a lady after all
>Also it would be hard to measure Sunset's slutty tits with just one hand and the other one fisting her pussy
>So she keeps it up
>She vaguely remembers old Sunset being around 32 inches
>She's already past 34
>35 now
>36
"Thirty seven... thirty seven inches and a half."
Sunset frowns.
She looks down at her huge round tits
"That would make you a..." she gulps. "A G cup, D-Darling."
"That's too small!" 
>She scowls and starts pulling the zipper all the way down.
>Her tits wobble free
"You know what? I want a second sizing. Naked."
>As the fabric slips past her hard nips, Rarity’s eyes focus on those engorged nipples, her stretched areolas, still carrying the signs of the scars where she begged the doctor to enlarge her tits and forever make her a slut
>Rarity’s mouth waters
>She cannot believe anyone could do that to herself
>Especially not such a wonderful girl as Sunset
>She is smart, willful and amazing in so many ways
>She has her entire life ahead and could do everything she wants, aim to the top spot in industry, politics, science
>Instead she decided to get her tits enlarged
>And she’s not even happy about her current size and find her kinds small
>And is probably thinking about going even bigger
>Rarity’s pussy by now is a molten crater of need. Each breath reverberates into her too-small chest as her own nipples are growing as stiff as and as hard and Sunset’s
>Speaking of which, Sunset has finished pulling down her jacket and showing off her tits in their complete plastic glory
>Rarity is not completely new to this kind of augmentation
>She has seen the movies everyone at school is watching, of course. The supposedly-secret porn series with big-boobed starlets begging to be slutty dolls and to be made obedient fucktoys for their Mistress
>But even the most enhanced starlet in those movies has nothing on Sunset
>Her tits wobble slightly, capped by two rosy nipples as thick as her thumb, a stark contrast from her orange, peachy skin
>She can see the scars, surrounding her areolas. She has heard sometimes an operation such as this one would leave a girl’s nipples permanently erect and extremely sensitive
>Sort of like a slut’s trademark
>And her boobs look bolted-on, rounded and sphere-like
>Her cleavage is deep and her tits push against each other, as if trying to outdo themselves
>Their profile is not the gentle slope she remembers, is a sharp curve that speaks of the thickness of Sunset’s implants
>She really did go all out
"Now I want you to do it all over again! And this time make sure to check! I wanted to be at least 38 inches and if I don’t get that I’m going for another filler in a week!”
"Filler? But I thought?”
"These are saline, Rares. Expanders. I'm keeping them in before I go for custom-made implants.”
>She smacks them.
>They wobble, hard and heavy. 
“They are not silicone. Not yet. I am going to swap them for permanent one as soon as I reach 40 inches, but so far I have to keep my training model.”
>Rarity lets out a strangled sound
>She is going even bigger
>And these are just her starting upgrade
"What do you think I’m going to look with 40 inches by the way? I think it’s going to be kinda sick! Nobody will miss me for the slut I am!”
"I think… nobody can… uh… I mean… they are going to get it even at this size.”
"Do you mean I shouldn’t go bigger? Because I totally am!”
"N-No… it’s just.. these are… they are really…”
>Oh, she is going to say it
>Right in the face of one of her best friends
>Her transformed, slutty friend
>Slutset Shimmer
"These tits really belong on a totally plastic slut!”
>Sunset beams, she’s positively giddy. She covers her mouth as she lets out a happy giggle and a blush spreads over her face
"Do you mean that? You really think that, even as small as they are?”
"Yes! You have the sluttiest tits in Canterlot High! Maybe in the city!”
"Thanks! Oh Rarity you say the sweetest things! Hey… do you think they look fake?”
"Yes! Yes… they look absolutely fake! Bolted-on! The fakest tits I have ever seen! People are going to take a look at you and understand you are nothing b-but a set of warm holes!”
"Ohhh, thank Celestia!”
>Sunset, relieved, falls back against the chair, her tits wobble once again, in such an unnatural, fake way 
>Rarity’s pussy sings
"You know I was really worried someone could think they were home-grown. Thanks Rares, I really appreciate it. You’re truly a good friend to confirm I am just a stupid slut!”
>She cups her colossal tits, pushing them together. She pouts, as if thy are still not enough
"They could be a little bigger, though… but let’s go for that sizing, come on!”
"S-Sure!”
>This time Rarity is going to have to touch them
>She cover them once again with her tape
>They tremble softly with Sunset’s excited breath
>Rarity’s hands used to be so steady, she was so proud of her skills as a seamstress
>Now she’s a nervous, horny mess
>She’s inches away from the best pair of tits she has ever seen
>A pair of tits Sunset desperately wanted to get and inflate so much
>And she’s probably going to love getting a grope
>But she’s a professional
>She’s a lady
>And she has standards, though by now it’s the barest thread keeping what remains of her sanity together
>Slowly she moved her fingers to cove the entirety of her pneumatic chest
>Rarity opens her mouth to declare her verdict
"Thirty… thirty seven inches and a quarter.”
"Damn! I knew 600 ccs was not enough! My tits are too small. Shame, I’ll have to ask for 800 at least… maybe 900 ccs, custom-made.”
>Rarity does not really have an idea about what those numbers mean
>She only knows they are making her so moist she's losing her breath
"Thank you, Rares…” she grins, that hungry light once again shining in her eyes
>She pulls her close
>Closer
>Sunset’s arms embrace her neck
>She’s so close she can feel the warmth of her skin, with each breath her taut flesh brushes against her nose
>Now or never
"So, I did not know you had a fetish for fake tits, Rares. What do you prefer? The size…”
>She shakes them in front of her eyes. 
>Rarity’s sharp blue eyes follow Sunset’s nipples
>Her mouth is dry
>She could just taste them
"… or the feel?”
>Sunset pushes her boobs against her face
>They are warm and so, so firm
>Her skin is so smooth and it smells softly of lavender
>She just gave her a face full of boob
>Just like a slut would
>Rarity’s mouth opens up in a mute scream
>She trembles, Sunset holding her against her deep cleavage as she drools all over her inflated chest
>She squirms and shakes as the orgasm rides through her 
>The musky scent of her pussy is overwhelming
>She pants and groans while Sunset patiently waits for the fashionista to enjoy her orgasm
>Rarity’s nipples make small dents against her blouse
>Her eyes are pinprick
>Her breath ragged
>She’s really excited
>Defenseless
>Slowly, deliberately, Sunset’s right hand detaches from Rarity’s neck and slips into her panties
>Rarity lets out a gasp and a powerless groan as Sunset’s index fingers touches her wrenched, hot pussy
>It’s almost like putting her hand in a warm honeypot
>She withdraws her now-glistening fingers 
>Puts them to her lips
>And sucks off Rarity’s juices
"Almost ready.”
>But suddenly the world is full of color and blinking lights and words and hushed whispers and what’s happening but it feels good so good she doesn’t want to stop neverr stop
"Ahhh…” Rarity gasps as the visor embeds itself into her conscience
>Burrows inside her motion control
>For a moment she hesitates
>Withdraws herself from the deadly embrace
>Looks up at Sunset
>She’s grinning
>Red-faced, horny beyond belief
>Sunset’s nipples are even harder than her own as she betrays one of her best friends in the whole world
"What… I…”
>That’s all she manages to say
>Then the subliminal hooks the visor put into her claw shut inside her mind
>She falls back
>Sunset gently lets her body slide on the chair
>Her head falls to the right as more lights swirl into her eyes
>Rarity has always been strong-willed
>The brainwashing goggles would have a much harder time breaking into her psyche
>Rearranging stuff
>Moving priorities around
>Rewriting patterns and introducing new ones
>If only she did not bombard herself with subliminals for all those long weeks
>Watching those porn videos that look too good to be true
>Like half of Canterlot High is doing by now
>Too late for regrets. Too late for even thinking about regrets
>Sunset passes her hand through Rarity’s silky hair
"It feels so good to betray you, Rares,” she says. “Like you wouldn’t believe.”
>She spreads her legs and it’s true: she’s completely drenched
>She got a very nice orgasm from putting her friend to sleep
"Now just let the inductor do its job,” she whispers to her ear
"When you’ll wake up, you’ll be a new person altogether.”
>Sunset is also a bit envious
>She never got to experience the inductor
>Not like that
>She was taken bit by bit, like an encroaching tide biting into a sandcastle
>Whatever resistance she might have she climaxed it away long ago
>Last bastion was probably getting her tits enlarged like that
"Still could have got them a little bigger,” she pouts as the thought resurfaces into her mind
>That thing about getting the idea about her new fake rack all of a sudden, though?
>That was another lie
>She knew she was turning into a slut
>Bit by bit
>A drop of lava burning through her cunt
>She couldn’t stop it, it felt just too good
>Sunset breathes in
>Inhales Rarity's scent, like mint-mixed musk
>Her hands roam all over Rarity’s body
>She’s slim and voluptuous at the same time, fit but not athletic like Rainbow, thick but not built like AJ, high-class but not to the point of being out of reach
>She’s going to be the best whore, Sunset just knows it
>Mistress would not have selected her to be the first otherwise
>Sure, not as good as she is, Sunset giggles and cups her enhanced bust
>Mistress loves her style the most. Going for a bit of a punkish and plastic kind of slut
>Rares is probably going to be the high-class one
>She gropes her round tits. They are soft and warm. They fill her palms perfectly, round and still very perky
"You could probably skip implants,” she mutters
"Though if Mistress wants you fake and plastic, I hope she’ll let me guide you.”
>Rarity gurgles something
>Maybe one last bit of resistance, bubbling up to the forefront of her brain
>Already forgot
"There is no escaping Mistress, Rares,” Sunset says in an aroused whisper. “She owns our minds. She owns our bodies. You are going to learn to love that.”
>She leans back against the chair. Her tits wobble now that they are free
>Her orange hand slides between her folds
>Her thumb caresses her hard clit while two fingers tease her folds
"It’s so incredibly hot watching another slut’s brain cooking up.” She clicks her tongue. “Especially if you're the only help she could get. Cadence was right.”
>She coos and groans as she rides her arousal down towards the first orgasm
>First of many
>After all Rome wasn’t built in a day and Rarity’s mind will not be rebuilt in one hour
>Plus the door is locked
>Plenty of time to enjoy the show
>Sunset tilts her head back and keeps assaulting her wet pussy while she watches Rarity being reprogrammed
>It’s going to be a long afternoon
"You’ll be such a good doll,” she forecasts
>And puts a brief kiss upon Rarity’s purple-painted lips
"One… ahhh…” 
>Sunset groans at the first signs another orgasm is coming shake her
“One down. Five to go.”

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The end - for the time being

Thanks for reading. This is a scene from a longer mind control story I am working on with Sunset and other girls from the EG world. Wonder who this mysterious Mistress might be? At this point not even I am sure anymore. My money is on Fluttershy. 

See you and lit up a candle to anon. It was thanks to you this got published. You know you.
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