“Mom you can’t be serious! You can’t just throw this at me out of the blue like this!” You cry as your mom sighs exasperated. You were just your average middle aged man, visiting home for Halloween. You had been looking forward to it given the new circumstances of your parents. Part of that was what you were arguing about now.

“I know it’s short notice, but she was just so excited to have an ‘older brother’ take her trick or treating! Can you not borrow something from a friend? You watched the show, didn't you?”

“I did but that doesn’t mean I went and bought Halloween costumes of any of the characters! I haven’t even dressed up for Halloween in years! What do you expect me to do? It’s the day OF the holiday. How am I supposed to find an adult pony themed costume in just a few short hours?”

“I-I don’t know.” Your mom admits looking defeated. You feel bad for her, but that didn’t change the fact that what she was asking was a tall order. “Sarah… Your foster sister wanted to be Flurry Heart for Halloween and we wanted her to feel appreciated and listened to. So we managed to get one together.” She continues to mix her batter while moving around in the kitchen. The counters were covered in baking sheets with various baked goods.

“Your father was supposed to dress as that Shining Armor guy pony and I was going as the Pink Princess, but he had to work and the school was down too many bakers for the sale tonight for me to back out! You’re the only one left to take her!”

“And I have no problem with that!” You call back feeling just as frustrated as she must be. “But I didn’t think I’d have to dress up! That’s the only problem!”

“I know I know!” She cries dropping the mixing bowl onto the counter with a rattle. “I just… I don’t want to disappoint her. She’s not had the best luck with families before and I just wanted to make her first Halloween with us a good one!”

You were about to argue some more, but instead decided to take a deep breath. You had grown up as an only child. From what you understood it was a miracle your mom was able to have you. Sadly that miracle did not repeat, no matter how much they wanted to give you a sibling. Finally as they were nearing retirement they decided to take in a foster child. This ended up being Sarah. She was a sweet, but excitable girl. The moment she met you she asked if she could call you big brother. She was already calling your parents Mom and Dad.

On one hand it was great she wasn’t resisting you. On the other, she tended to go too much too quickly and had to be told to calm down. She was mostly a good kid and seemed to understand, but you guessed after three failed housing attempts, she was a bit quick to latch onto doing whatever it took to make this work. To be the best daughter she could.

Which is why you hated it just as much as your mom that you might not be able to make this dream of hers come true.

“Look I’ll… I’ll go check the local shops. Maybe some mom and pop store will have something left over? I have a few hours right?”

Your mom’s response is to hug you tight. “Thank you! I’m so sorry to have to spring this on you at the last minute!”

You mentally sigh. How can you be mad at her or your new sister for this?

“Just… we’re probably going to have to explain to her why I don’t have a costume, you know that right?”

“I-I know. We’ll cross that bridge when we come to it. If we come to it..” She rubs your back a couple of times before letting you go. With the best smile you can muster you tell her goodbye and rush out to your car. A map of the area already forming in your mind. You’d still check the major retailers, and costume shops, but you think you might have an idea where some temp shops might have sprung up. In any case you were going to give this your best shot!

Onward!

***

It was several hours later with the night sky threatening to take over as you slowly drove down another road, your eyes scanning for anything that might have the slightest HINT of a Halloween costume for sale.

The bigger retailers did have pony costumes... For five year old girls. Somehow you got the impression those wouldn’t work out for you. It was getting way too close to when you’d have to take Sarah out to Trick or Treat. Much of a shame as it was, this was likely the last road you’d be driving down. It sucked, but you were likely going to have to figure out how to tell her your costumes weren’t going to match…

Wait what was that?

In the window of a small shop was what appeared to be a costume with the My Little Pony Logo on its card. What’s more, the thing was huge. No way that one was a kids costume! Still you were honestly surprised you were able to notice it while driving by. It was almost like it called to you. Quickly finding a parking spot, you leave and lock your car before rushing toward the shop.

It’s only now that you notice the large ‘Going out of Business!’ sign hanging about the door. The place seemed to be a very small thrift store once upon a time. Well that or it was a place that sold random nick nacks. The entire thing looked… odd. Still if that was a pony costume for adults that might fit, you’d take it. You just hoped you had enough money. You weren’t exactly rich. Still, you’d spend every last cent if you had to.

A small bell rings as you enter, taking you back to decades long past. It was seriously like walking into the past. The shelves weren’t exactly packed, but there was a decent amount of stuff on them. The odd thing was it sorta looked like one of those shops you’d enter in some dungeons and dragons campaign. Sure there were the occasional board game or other retro toys on the shelves, but there were so many little glass bottles of random liquids and other oddities that made you wonder if you just walked into a wizard’s shop.

“Oh! Hello!” A rather excited and frankly pretty woman exclaimed as you entered. You hesitate for a second. You haven’t exactly had much luck in your love life and here was this rather gorgeous woman talking to you. You knew she was just doing her job as the sales clerk, but still, a few daydreams danced about your head. She was just that stunning.

“We don’t have much left, but I’m sure we can find just what you need.” She says while really putting her all on the word ‘need’.

“I uh, saw you had an adult costume for My Little Pony?” You manage to get out, mesmerized by this mysterious woman. As beautiful as she was, there was something… different about her.

She had short white hair and was wearing your typical witch costume. Well almost typical. Her leggings were mistached. One green, one orange. She was also wearing contacts, at least they had to be contacts, given she had yellow eyes with red pupils.

“Oh yes, something I found buried in the back.” She replies with a shrug of her shoulders. Her smile sends shivers of both interest and apprehension through you. She’s alluring yes, but you get this feeling she’s dangerous.

“Honestly I can’t imagine we’ll sell it this close to closing, and on the day of Halloween at that.” She continues gesturing at the costume hanging in the window. “So if you want it I’ll give it to you for five bucks.”

Five bucks!? That’s a steal! Wait, calm down, you don’t want to appear too eager and give a reason to drive up the price.

“Wow, that sounds pretty good. I’ll take it.” You manage to get out calmly. Walking over you pull down the costume and freeze, finally getting a really good look at it.

What you hold in your hands is very much a Queen Chrysalis costume!

“What’s wrong? Don’t think it’ll fit?” The clerk calls out with a soft laugh. Seeing your expression tells her everything. “Looks like I hit the nail on the head huh? Don’t worry about that. I can personally guarantee it’ll work out for you tonight.” She gives you a wink and a smirk. Neither exactly fills you with confidence.

“And what the heck? I’ll throw this in as well!” She pulls a flower broach out from under the counter. It’s a flower unlike any you’ve seen in the wild, yet something about it is eerily familiar. The flower itself is red with black spots near the base of the petals. Well maybe not red, but a reddish purple? It does look rather pretty though, and expensive! Was she really going to give you this costume for five bucks and that for free?

“I uh…” You look down at the costume. You’d look silly crossdressing, but after searching all afternoon it was the only adult costume for pony you’d seen. The price was good and you got a nice free gift. Yes this whole thing seemed weird, but were you really going to find a better deal? In the end it was the thought of Sarah’s smiling face that tipped the scales.

“Sold.” You say quietly, yet firmly. You’d probably get made fun of for it, but welcoming Sarah was worth it. You were going to make this a night she wouldn’t forget! Therefore you hand over the five bucks and take both your costume and broach.

“The costume should fit you fine.” The clerk reassures you with that mischievous smirk of hers. She then leans in and whispers: “And that broach just might be your means of wishing your way out of a tricky situation.”

There was no wink following that exchange. Though she kept her smile, something about the way she said it gave the impression she wasn’t kidding around, but what in the world could that even mean?

Feeling a little freaked out you rush back to your car with the items, determined to get home and away from here rather quickly. You tell yourself it’s just so you have time to change into your costume nothing more. You certainly aren’t afraid of a silly little thing like a closing down shop! Or the sexy, yet frankly terrifying woman running the counter! Nope! Just concerned you don’t have enough time to get dressed in time! Yep! That’s it!

As you continue to lie- that is ‘reassure’ yourself of these facts. You don’t happen to notice the clerk watching you as you leave. After a few minutes of you being out of sight, she snaps her fingers and the store fades away. Leaving only an empty storefront in its wake.

***

“Huh… it does fit.” You stand there looking in a mirror at yourself all dressed up in your five dollar costume. It’s basically a human version of Queen Chrysalis costume. You don’t get any sort of face mask or anything, just the basic outfit. An outfit that consists of a long black dress with a green ‘belt’ like accessory. Next you get arm and leg ‘stockings’ that have holes all throughout them. Despite that they are surprisingly sturdy. Last of all you have a headband with her classic little crown thingy on it.

“And you look wonderful! Now hold still while I finish your makeup.” Your mom beams as she applies various forms of stuff you couldn’t possibly hope to know the names of. The most you got was there was blush and eventually lipstick to be involved.

“Is it really necessary for me to include the makeup it came with?” Come to think of it, why did this costume even have make up in the first place? You kinda feel you got a much better deal than you thought for five bucks. The costume was simple, sure but man was it ever well made!

“You’re the one who wanted to crossdress tonight.”

You feel your face flush. “I DIDN’T-”

She cuts you off. “I’m just teasing! Relax, it'll make Sarah happy that you put in so much effort.”

Sighing, you just keep quiet and let her finish. This was going to be humiliating alright. God you hope no one you know sees you! How did you let your mom talk you into this?

“I’m hoooooooooome!” Came a shrill happy voice from the living room. Sarah, the star of the hour, rushes in all made up in her costume. You’re honestly impressed. If you didn’t know any better you swear a human version of Flurry Heart just stepped from the screen into your world. Her hair, her dress. It was pretty perfect. Even more impressive she’d been wearing that all day and to school! No way your mom and dad just ‘threw this together’ like they said!

“Oh my gosh! It’s Chrysalis!” Sarah screams while jumping around you. “You found a costume brother? That’s so cool!”

“Yep and he’s just about ready to take you Trick or Treating!” Your mother adds while applying the lipstick, and thus final portion of your costume. “Now go like this dear.” She says to you while puckering her lips. You try your best to copy the movement and behold the result. Yep your lips were green because of course they’d use green instead of black.

Looking in the mirror you do your best not to cringe. Honestly the quality of the costume itself wasn’t the issue of course. Just you still couldn’t quite get over you were crossdressing. If only you could pass as a woman.

Weird, you felt a bit hot there for a second. You hoped you weren’t getting sick.

“Hey uh sis, hope you don’t mind I don’t exactly have the right build for this but it was the only costume I could find…” Whatever, the important thing was that Sarah seemed to be okay with it.

“I don’t mind!” Sarah cries looking happy as can be. “We’ll just say she’s using a disguise to look male! I’m just happy your costume goes with mine!” She then puts her arm against her forehead and does her best ‘woe is me’ delivery. “Oh no! Please Chrysalis! Don’t use me as bait to lure out my parents!”

Despite the fact you’re sitting there in drag about to go out in public like this, you can’t help but laugh along with her and your mom. She really was just so precious. You could feel the love oozing from her. The sweet, delicious love…

You shake your head. ‘What in the world was that? I’m getting a bit too into character and we haven’t even gone out yet!’

“I’m so sorry we can’t go with you dear.” Your mom says as she hugs her new daughter. You’re reminded of just how much this must hurt her and your dad. Sarah’s first Halloween and they couldn’t attend. Well you’d just have to make sure you did all you could to make up for that! Embarrassment be damned!

“It’s okay mom.” Sarah replied, looking far more mature than most girls her age would. “We’ll go next time. For tonight I’ll make sure my big ‘sis’ and I take a lot of pictures!” She grins up at you.

Okay maybe some embarrassment be damned.

“Do we have to?” You moan out. You don’t want to even think about what your friends will say when they see those pictures.

“Of course! Maybe even some video too!” She laughs while skipping around the room.

Well if you’re lucky maybe she’ll forget all about that once you’re out. You take one last look at yourself in the mirror before getting up to grab her bag and other essentials. You had to admit, one of the best parts of the costume was how it made your eyes an emerald green. These were some contacts!

…wait you didn’t put on any contacts.

***

“That’s right everypony! Flurry Heart here vlogging her her first Nightmare Night! I’ll be sure to tell you every detail as they come!” ‘Flurry Heart’ as that’s what she insisted she be called tonight, was prattling on while holding up her smartphone as you followed meekly behind her. Of course she’d do this. Of course.

“You know ponies don’t have phones so Flurry wouldn’t do this.” You try to interject, oh so hopeful you could get her to stop.

“Hey we know phones get invented sometime! Princess Pip had one!” She shoots back. “We don’t know they aren’t around when Flurry grows up! Or maybe I’m the Equestrian girl version!” You roll your eyes. So much for that attempt.

“I’m surprised you didn’t just go as Princess Pip with how you’re acting.”

“W-Well it’s not like I have a twin sister to be Zip.” She says, her voice a bit lower than her previous volume. The response stung. You’re sure she’s happy being in your family, but the lack of a sibling her own, or even close to, her age must suck. She’s the type of girl that would probably love having a twin sister. Sadly you’re several years too old, and the wrong gender.

“I-I’m sorry.” You blurt out. ‘Flurry Heart’ just shakes her head. “Don’t be sorry! I love you and mom and dad! Honest!”

There was just a hint of fear in her voice. You still didn’t know all the details, but the short of it was every time she was welcomed into a home, something happened that made it short lived. It hadn’t been because of her, or anything like that. It’d just been bad luck. So you knew. You knew she was afraid of being sent back again.

You didn’t want that to happen with your family. You didn’t want her having to live with that fear.

“I know, and I’m happy to be your captured queen of the changelings.” You put on your best Chrysalis impression. “But mark my words vile Flurry Heart! I shall be free and you will all rue the day you crossed me!” The little hisses you add at the end seal the deal, luring out a fit of giggles from your sister.

“Thanks ‘sis’.” She winks at you. You wink back but can’t help but add in a playful tone:

“Hey don’t call me sis! I told you this was all I could find!”

More giggles. “I know, and you look great!” She smiles,“still it’d be so cool if you were a girl and really fit that costume! I bet you’d make a great Chrysalis!”

“Thanks I think.” You reply back. You can tell she’s trying to be genuine, even if the thought is a bit weird. You’re sure she doesn’t want to replace you with an older sister instead, but at least part of her really wishes you fit the costume perfectly, and in all honesty you wish you could-

“Guh!” Without warning a strange heat builds up in your stomach causing you to clutch it and hunch over.

“H-Hey big brother? You okay?” Flurry, or rather Sarah asks with genuine concern.

“I-I don’t know I-” You try to formulate words, but the heat suddenly burns through your body. Starting from your stomach and going out to envelop your entire being. The world blurs for a second as flashes of green pass by your eyes. You swear it almost looked like green flames just washed over your body.

“What in the world wa-” You shut your mouth. That is NOT your voice. You try to ignore who it reminds you of, but it is NOT a voice that should be coming out of your mouth!

“B-Brother?” Sarah whispers in disbelief. “I-Is that you? Is this part of the costume? A magic trick? H-How did you do that!?” Her voice gradually grows louder and louder in excitement. You’re only glad the street was a side street and still empty. Somehow you knew you didn’t want to draw attention to… just what did happen? Forget the voice, your entire body felt weird.

“I-I don’t… why is my voice so weird? I feel so weird.” You look down at your arms. Your slender feminine arms. The long gloves you were wearing match them much better now. You take a glance down to see your legs only to freeze. Right there on your chest are two rather massive lumps. Lumps that you can see down the cleavage of!

“W-Why do I have boobs!?” You cry cupping them without thinking. Sarah for her part is too busy running around you to notice. Just as well, you quickly let them go. That felt… you don’t want to think about how it felt!

“Wow you really do look like her as a human!” She cries poking you in various spots. “Really bro how did you do that? Or should I say sis? You really ARE my big sister now!”

“H-Hey stop that!” You cry. You were still trying to get a hold of the situation to really register what she was all saying and her poking wasn’t doing you any favors. So you put on a Chrysalis costume and while walking suddenly became a copy of her as a human? What? How is this possible?

Suddenly the look of that store clerk flashes in your mind. Was she a witch? Was this magic? How else could you explain it!?

“Hey sis? Are you okay? This didn’t hurt, did it? Y-You are still my big brother right?” She was getting scared. Time to be the older sibling you were supposed to. Even with all this going on, panicking wouldn’t help. Still you weren’t sure how you were remaining so calm.

“I’m still me.” You say in a much steadier tone. “I-I’m not sure how I’m like this but it’s still me in here.”

“Wow…” Sarah replies, continuing to look you over. “So it is a magic trick?”

“You could say that…” Yeah a trick you weren’t in on!

“How’d you do it?”

“I-I think it’s the costume.” You reply honestly. The only explanation you could come up with was that the girl at the shop was a witch and this was a magic costume. If you didn’t just switch sex you’d think you were crazy.

“That's some costume!” She cries, all happiness and energy again. “Now you really look the part! I’ll get so much candy!”

“N-Now hang on just a second, I need to get my uh… bearings.” You just went from a middle aged man to a woman likely in her mid or early twenties. You weren’t even sure you could move like this! Taking a few hesitant steps forward you found that thankfully you were able to walk without problems. Your high heels click clacking against the sidewalk as you went with ease.

Wait, high heels? The costume didn’t include those! Did they come with the transformation!?

“Hey so are you going to be like that all night? Can you change back? I mean you are a changeling. The queen of them!”

“I uh… I don’t know?” Good question though. If you were a changeling did that mean you could transform into your old self? You try to imagine becoming your normal male self, but nothing happens.

“I mean maybe, but I don’t know how I did this in the first place!” You wave your hand over your form. Damn you kinda wish you had a mirror. You were likely a really sexy woman. Mmm you could just walk into a party like this and every boy would freely give you love-

W-What the hell are you thinking? You slap your cheeks, trying to clear your mind.

“Uh are you sure you’re okay? You’re acting weird. Is it because it’s weird to be like a girl when you’re a boy?” She tilts her head. “It’s too bad you couldn’t just find a Shining Armor costume. You’re my bro and not my dad, but I guess it’d be less weird for you. I wish I could help you with that.”

“Y-Yeah I-” You go to reply but that heat from earlier suddenly springs up in your gut again. In mere seconds the green flash washes over your eyes, and you feel noticeably male again. Except way more bulked up then you ever were previously.

“W-Whoa you did it again! So you can change like a changeling!” She exclaimed excitedly.

Blinking you look down to see yourself dressed up in a red military looking outfit. It doesn’t take you long to recognize the uniform Shining Armor wore during his wedding. Complete with chest plate symbol.

“I-I didn’t do anything though!” You cry, noticing right away your voice was very much Shining Armor’s. Naturally, while you didn’t want to admit it, your last voice was that of Queen Chrysalis.

“So… how are you changing? I know it’s the costume but how do you get it to do it?” Sarah asks. You shrug your shoulders.

“I don’t know! I’m just standing here! You’re the one listing characters!”

“Wait, so am I doing it?” Sarah asks, looking you over. “So… uh it’d be cool if you were an exact copy of m- Whoa!”

No sooner did she begin to speak then the warm heat flared back up. Another wash of green and you were suddenly shorter. Much shorter, and sporting the same long hair and costume of your sister. A quick glance down confirms that yep. You’re a little girl looking exactly like her!

“Wow! A twin sister!” She cries hugging you. The sensations going through your mind are causing a near short circuit.

“S-Sarah! Stop!”

“Nuh uh! I’m Flurry Heart tonight! Only call me that!”

“But Flurry!” You clap a hand over your mouth.

“That’s the spirit!” Flurry laughs before letting you go. “Now to fix you.”

“Fix m-” Another heat and flash and you’re tall again, sporting the same Shining Armor get up you just had on.

“I bet it’s pretty weird being a girl huh? I can let you be a guy for now.” She smiles. “Now come on! Let’s go get some candy! I can’t wait for you to do this trick in front of people! They’ll never figure it out! Oh! I could keep changing you into other girls and you could go to the same place and get like five times the candy!”

“What? H-Hey! Wait! Flurry Heart hold on sweetie!” You cry after her, trying to keep up. Man she got this energy from her mother, you were sure of it. Wait, you weren’t married and she wasn’t your daughter! Just what was going on?

No time to ponder it though. Flurry had decided to go full force into the fray and was already skipping ahead. You could only rush along helplessly as she-

***

You find yourself back in the costume shop. No not the you in the story, the you now. The you reading this story.

The pretty clerk in the witch outfit from before greets you.

“Greetings! I’m sure you’ve guessed at my true self, but let’s forget that for now. You have some choices to make. The last line of the story is “You could only rush along helplessly as she-”

“As she what? That is up to YOU to decide! Choose wisely! You have six paths you can explore before you, but time enough to check out only three! After picking a scenario you’ll go down that path and see the start of what it might offer before your sister will run off again! At that point you’ll be given a choice to check out one of the five remaining scenarios. Then one of the four remaining. When only three scenarios are left, those three shall vanish! Never to be explored!”

“Once all three scenarios you’ve voted for are chosen, you’ll be presented with another poll. This one asking you which of the three chosen scenarios you’d like to revisit and get closure on. You’ll only be able to pick one.”

“Then one final vote will be given. The vote of what type of ending you so desire.”

She winks. “And in another break of the fourth wall, see the Author’s notes for the link to the poll and the choices available.”

The lights fade as the shop is swallowed in darkness, only her eyes still shine with light.

“Happy Halloween, and Nightmare Night!”

Author's Note

Okay so here is the deal. The story will be uploaded here for free, but voting is specifically on my Pateron page, and I'm sorry yes you have to be donating at least one dollar in order to vote.

With the Holidays coming up, I'm trying to do what I can to make sure I can get through it. I completely understand if you don't want to vote on this story, or can't afford it.

The link to the first poll will be at the end of these notes. You will be given six scenarios to choose from. As I tried to say in the story. I'll make sure you are able to explore three of them. What this means is you'll go explore one of the six options I list, and I'll write who you turn into and what happens to you in that form. This will be one chapter at which at the end Sarah or 'Flurry Heart' will run off and you'll chase her to the next scenario. Which you will also vote for from the remaining ones you haven't explored yet.

Once you've voted for and seen three of these possible scenarios, I'll put up a chapter that will lead to the final poll. This will be a poll for which of the three scenarios you chose that you want to go back to and finish up. You'll once again become the character you were the first time around in that scenario and will end up closing out that situation. This will likely lead to sexy times.

Finally once sexy times have been written and are over. You'll have one last poll to vote on. Namely which possible ending you want. There will be a list of three.

One where you change back into your male self. (These endings will be basic, but try to be good endings.)

One where you stay changed into the character, but still end up in a pretty good situation.

Then the twisted ending. These are the ones that might dip a bit into the dark...

With all that said, I really hope this ends up being fun. Now for those who want to participate here is the link to the poll!

https://www.patreon.com/posts/very-nightmare-114212149