The Curious Tale of Dr Shine and Ms Sparkle.

Shining Armour paced back and forth in the living room, Cadance looking more and more worried at what they had just found out.

“What are we going to do about Dusk?” Shining asked, “This is too serious not to tell princess Celestia. What if this happens in front of Mom and Dad?”

“I just don’t know Shining.” Cadance answered, “Auntie Cellie is usually so understanding when it comes to moments like this.”

I could over hear my older brother and sister-in-law from my bedroom, I’m not surprised they were wondering what to do with me. I mean they just saw what happened and my secrets more or less out in the open. It didn’t help I was still hot and horny, maybe I could sneak out...teleporting would be to loud but flying was quiet enough.

I got dressed, putting on a simple black night dress, quietly opened the window and flew out.

It felt good to up in the sky again, the cool breeze was like silk caressing over me. I flew over to the Apple Acres, hoping to spot a certain red stallion but to no luck. I figured he must be inside given the time of night. I gave a quick peek into each window until I found his bedroom, and gave his window a light tap.

“Twi?” Mac asked confused as he opened his window, “What’re yer doin’ here at this time at night?”

“We need to talk...” I said simply, “About a lot of things. Is anypony else here?”

“Nope, Applebloom is havin’ a sleepover and AJ is out drinkin’, heck even Grandma is out visiting family. It’s just us Twi.” Mac explained, as he let me in. “What’s eatin’ yer?”

“My older brother found out...” I explained, “He’s probably writing to the princess as we speak.” Mac sighed and urged me to sit down.

“Ah figured this would happen.” Mac stated, “Was only a matter of time really.”

“I know and I’m scared Mac.” I stated, bringing my knees up to my chest. “I don’t know what Celestia is going to do to me.” I know Shining said she only wanted a talk, but I couldn’t help but worry.

“There’s something else ain’t there?” Mac asked, I blushed a bit and gave a far off smile.

“...I-I can’t stop thinking about you Mac.” I admitted, “I haven’t been able to keep you off my mind since...you know.” Mac raised a brow out of surprise.

“Twi...what about Dusk...and Luna?” Mac asked concerned, “Ah mean yer sure?”

“Why do you think Duskie was staring at you?” I answered with a small smile, “We’re the same person after all. After all this I doubt Celestia will let Luna anywhere near me.” My smile quickly vanished, “I don’t think she would want me once she finds out, I mean look at me.”

Mac didn’t know what to say, he was very hard pressed at the moment. Twilight was a very beautiful mare, there was no way to deny that and he couldn’t help but get flashbacks of that time in the barn when he first found out about all this.

“Ah see a very beautiful mare Twi.” Mac admitted, “Ah would have to be a blind fool not to see that.” I smiled, I kind of noticed and giggled. I was very flattered he wanted me.

“You’re sweet do you know that Mac?” I admitted as I crawled over and straddled his lap, “Despite everything that’s happening, right now I just want you to make me yours.” I snaked my arms around his neck and kissed him.

“Do you think I should check on Dusk?” Cadance asked, “She’s been quiet for some time now.” Shining looked towards his younger brothers bedroom, she was right Dusk has been too quiet.

“I’ll go and check.” He offered, as he made his way up the stairs he felt a chill and a faint breeze. When he opened the bedroom door he was met with an empty bedroom and an open window. “Oh for...Cadie Dusk’s done a vanishing act!” Cadance came running and gasped as she knew fine well this couldn’t be good.

“Oh no...” Cadance looked worried, “Where’d do you think she went? Should we look for her?”

“Damn it!” Shining cursed, “I’ll go out and look, Celestia’s going to be here first thing in the morning and Dusk just ups and vanishes! We don’t need this now!”

“H=haaaaaah Mac! Harder! Fuck me harder!!” I moaned out, as Mac pounded and thrusted back and forth into my wet pussy. I was face down on his bed with my plump plush ass in the air, juggling slightly with each timed thrust, “Fuckfuckfuck!”

“Ah take it yer like ridin’ this stallion?” Mac leaned over and whispered. He slowed his thrusts down to a teasing pace. I felt him groping and squeezing my generous breasts sending shivers down my spine, each squeeze and tweak of my puffy nipples intensifying the feeling even further.

“A-Ahnn...y-you...damn...oh fuck! Tease!” I groaned out, “Y-you really...h-haah! Know how to make...oh fuck...a girl feel special!” Mac picked up his pace a little more, I could feel every huge inch of his shaft being swallowed up by my tight, cock hungry marehood. “Oh fuck...” I groaned out.

“Dusk!?” Shining called out hoping for an answer, only to be met with the dead silence of the night. “Damn it!” He cursed, “Where the hell could you have run off to?”

Shining had been looking for next to an hour now and there was still no sign of his younger brother turned sister. Celestia knows where she could be, and even worse somepony could be taking advantage of her.

“Oh fuck Mac!” I grunted as I rode Mac, grinding my hips back and forth as he sucked and teased my tits, one hand groping and squeezing my fat ass. “H-haaaahhhhh!” My breasts felt so sensitive, and the electric feeling that washed over my body with each tease, grope and nibble was heaven. I began grinding even faster, rocking back and forth on his dick, I couldn’t help it my hips had a mind of their own I just wanted to milk that cock for all it’s worth. “Fuckfuckfuck!” Mac grunted and moaned as I rode him hard.

“U-uh...Twi y-yer...so...fuck...s-so f-fuckin’ tight!” Mac groaned out with each rhythmic thrust and grind into my soaking wet cunt.

“H-haah...W-well I hope...oh fuck...you realise...Hah! I-I’m gonna...fuckfuckfuck! Drain those...b-balls dry!” I said in between each thrust and grind. Mac’s response was to thrust harder, fuck I could feel him stretching me inside, by the stars I felt so wonderfully full.

“Any luck Shining?” Cadance asked worried, when her husband came back through the door. Shining just sat down and sighed.

“I couldn’t find her anywhere.” He answered in a defeated worried tone, “I don’t suppose you could find her with your magic?”

“I can feel a massive amount of desire, lust...and love, but it’s too far away to say where.” Cadance explained as she tried her magic to find her brother turned sister in law, “Whoever she’s with it’s obviously someone she trusts.”

“...” Shining just glared off into the distance, he had an idea where but he decided to leave her be for now. If she wasn’t back by the end of tomorrow morning he was going to have a few words with a certain apple farmer.

“M-Mac!!” I screamed in my lustful haze, “I’m gonna...!” Mac was thrusting into me faster and harder, “I’m gonna...!” Mac grunted, moaned and let out a roar as he filled me up with his seed. I screamed as I rode the waves of an massive orgasm. “S-so...full...” Mac collapsed on the bed exhausted and I curled up beside him resting on his chest, that felt so good. We were both sweating and breathing heavily, my pussy felt so blissfully sore and I could felt trails of Mac’s cum drip down my thighs. I didn’t doubt I would be walking with a faint limp in the morning.

Mac let out light snore, I giggled tiredly as I slowly felt sleep take me.

“What do you mean Dusk is Twilight!” Luna cried out at Shining Armour, “Sister did you know of this?” She turned to her elder sister who just nodded.

“I’ve had my suspicions for a while now, but Spike’s letter all but confirmed it.” Celestia explained calmly, “I trust that Dusk didn’t give you two any trouble?” Shining Armour frowned, while Cadance just blushed trying not to make her aunt’s gaze.

“...” Luna fumed, “Do you to know what Twilight did to me!”

“Nothing you certainly didn’t enjoy Lulu.” her sister joked, “I remember your face whenever Twilight was mentioned.” Celestia’s expression turned serious, “I take it Dusk has been getting some...side effects from this issue?”

“Yeah, Dusk has been acting more and more feminine princess.” Spike explained, “I think he’s shrunk a bit too.”

“I figured as such,” Celestia commented, “I would imagine Twilight is affecting Dusk on some level, but I can say the same the opposite was true as well.”

“Well it would explain what she said,” Shining groaned and rubbed his temples, “All she really wants is to be happy.”

“That’s to be expected, and I’m relieved to hear that.” Celestia commented, “I’ve read Dusk’s notes for this spell, and to be honest it was a stroke of genius though the mistimed appearance of the moon was my fault.”

“Y-your fault?” Everyone cried, a look of shock evident on their faces.

“Well I couldn’t seem to find my sister anywhere in the castle, so she could do her nightly duties.” Celestia gave her younger sister a disapproving look, “So I took the liberty of doing it instead, though I had no idea what I had started.”

“Uh...?” The sun was too bright this morning, By the stars my head was pounding and why did I feel so sore between my legs? I felt warm and in my tired daze I snuggled into something soft and plush. I gave a tired sigh of contentment as something pulled me closer till I could hear soft snoring and the rhythmic beat of someone’s heart.

“Uh...mornin’” A strong male voice spoke up in a tired drawl.

“...oh...m-morning Mac...” I replied tiredly with a yawn. “M-MAC???” I shot up awake which I soon regretted as the soreness between my legs prevented me from walking and standing properly. I quickly noticed we were both naked...d-did we? O-oh Celestia...w-we did d-didn’t we!

“...Ah suppose Ah’ve got some explainin’ to do.” Mac groaned, I nodded too shocked to say anything. Mac explained everything to me as best he could anyway, I-I wanted to deny everything but with everything that’s happened in the past few days I knew deep down he was right.

“The princess is going to kill me...” I muttered on the verge of breaking down. Mac put his hands on my shoulders to reassure me.

“Somethin’ tells me that the princess only wants to have a talk with yer.” Mac reassured, “You can’t be blamed for everything yer did as Twi.”

“Look at me Mac.” I asked him, “I’m a freak, what kind of pony am I? I can’t control these changes and look what its doing to me!” I had shrunk in height, gotten slimmer, I had wider hips than a stallion should have, not to mention the fact I have a softer looking face now. “And don’t get me started about turning into a nymphomaniac!”

“Yer not a freak Dusk.” Mac reassured me, “Ah admit this is gonna take some gettin’ used to, and yer know yer friends are gonna have yer back.” I winced in pain at the soreness between my legs.

“I’m not going to be able to walk or fly back home like this.” I moaned, Mac gave me a concerned look.

“Ah could carry yer home.” Mac offered, “It’s still early for anypony else to be up right now, Ah can offer yer a shirt too if yer don’t mind wearin’ what yer came here in.”

“I’ll take what I can get.” I replied disheartened, “I just want to go home.”

I’m thankful it was still early in the morning, and the fact everypony seemed to enjoy sleeping in on the weekend. I had put on the nightdress Twilight had worn last night and an oversized shirt Mac had offered me. Mac was carrying me bridal style, if anyone could see me now they would see me blushing bright crimson.

I didn’t have a doubt that the princess was going to scold me for this mess I’ve gotten myself into. There wasn’t away to reverse these changes is there? I was doomed to live a half life between being myself and Twilight Sparkle. I could barely recall the feeling of the change, and I hated to admit it but there was a part of me who yearned for it.

“Is there any sign of him?” Shining asked pacing back and forth, he was worried sick about his younger brother just flying off into the night to who knows what.

“He’ll be here soon.” Celestia said simply, feeling a familiar pulse of magic, “Dusk is on his way back now, and he’s with someone. I can only assume it’s whoever he flew off to see.”

“H-he’s with someone?” Luna piped up, “We assume this was Twilight’s doing.”

“I would say so Lulu.” Celestia commented, “Just remember Dusk wasn’t in control when Twilight comes out so don’t be angry with him.”

Mac and I had entered the living room, where everyone was sitting and waiting for my return. I was still being carried bridal style, blushing like crazy. Everyone was giving us a wide eyed look, Celestia raised a brow out of curiosity and Luna looked a tad jealous. My older brother looked like he was going to kill Mac however.

“I-It’s not w-what it looks like!” I blurted out.

“Please put my student down Macintosh.” Celestia asked, “I assume you’re aware of Dusk’s situation?”

“Ah am yer majesty.” Mac answered as he placed me down on the couch by my brother.

Luna and I couldn’t meet each others gazes out of the awkwardness between us. Cadance looked at me and Luna and realised we had it bad, but there was another case with Mac and her brother-in-law.

“A classic triangle...” She muttered under breath.

“Now Dusk...” Celestia spoke up getting my attention, “What do you have to say for yourself?”

“I-I don’t know what to say...” I admitted, “I didn’t realise this was happening whenever I blacked out. There’s no cure for this is there?”

“I’m afraid not my faithful student, you’re going to be stuck like this for the rest of your life.” Celestia said sadly, “Moonlight enhanced spells are permanent, the ingredients you used imbued their properties onto you.”

“O-oh no...” I looked absolutely heartbroken, I knew what ingredients I used and what they could do when imbued with moonlight on their own, but all of them at once...

“Your transformations are fuelled by sexual desire and lust Dusk, and Twilight is acting out on those desires.” Cadance added, “It would explain why you went after Luna originally.”

“...” I said nothing.

“Not only that Dusk whatever is causing this is trying to balance out your body to be closer to that of Twilight’s.” Celestia continued, “Though I doubt you’ll change any further than you have already.”

I sat through the lecture Celestia was giving me, I was kind of relieved that she wasn’t going to banish me or anything but it was kind of embarrassing that she wasn’t going to question my choice in sexual partners, just as long as I was careful.

“We’re going to stay here a couple more days just make sure Dusk is alright, if that’s alright with you auntie.” Cadance suggested.

“Yes of course.” Celestia agreed, “I’ll let you help Dusk get adjusted to the new changes in his life.”