“Well I guess it’s time” Rebecca Thomas laughed as she walked into her sister Erica’s bedroom.

“What are you talking about?” Erica asked looking up from her book.

“Dad asked me to take you bra shopping and…” Rebecca started.

“No! I don’t need a bra! No one can see anything I can…” Erica began to blush and rant.

“Settle down sis…it’s not that big of a deal. Every girl…or should I say young woman…has to do this and with Mom being out of the picture; Dad can’t handle this one so he asked me to step in” Rebecca said taking a seat on the end of the bed.

“That’s easy for you to say” Erica replied.

“It wasn’t when I was your age. Aunt Cheryl took me for my first fitting and then I just took it from there. So at least I can help you out”

“Can’t I just wait until I get to my permanent size and then start buying them?” Erica joked.

“Nope! And anyways, you’re 11 now and the boys will begin to pay attention so you need to do this” Rebecca reminded her.

Erica let out a huge sigh and slumped forward “Fine. I’ll go”

“You never really had a choice haha” Rebecca said.

Rebecca was 20 and a junior in college. She had always looked out for her little sister and was fiercely protective of her. She also had a way of making the younger girl laugh when she needed it which she figured might come in handy today.

Rebecca stood up; at 5’8” she knew she’d always be taller than her little sister who at 11 was 5’2” but hadn’t grown in the last 6 months.

She smoothed out her denim shorts, wiggled her toes in her brown sandals and adjusted her blue and white polka dot shirt “You ready?”

Erica stood up “I guess” she shrugged. Her green t-shirt went up and down untucked, it hung over her black shorts. She slipped her feet into a pair of flip flops and tucked her long blonde hair behind her ears.

Rebecca adjusted her top knot, catching stray dark blonde hairs in her light blue painted fingertips. Her toes were painted the same sky blue color which matched her eyes.

Erica’s eyes were brown and her face was rounder than her sister’s oval one but there was definitely a family resemblance between the two.

They hopped in Rebecca’s car and headed to the mall and Macy’s.

“I don’t get to go to Victoria’s Secret?” Erica asked as they went into the department store.

“Not yet…don’t waste your money on bras you’re going to outgrow fast. When you stop; then you can splurge” Rebecca cautioned. “Besides; they’re having a professional here today to measure and you need to start somewhere”

“No! Nope! Not gonna do this!” Erica turned on her heel and began to quickly walk the other way.

Rebecca used her longer legs and strides to catch Erica by the shoulder “Everyone has to do this…quit being such a baby” she laughed. “If it’ll make you feel better; I’ll get measured too okay”

“You go first” Erica said.

“Of course” Rebecca agreed. “I’ll go and you can see how harmless and easy it is…I might pick up a new one for myself while we’re here anyway”

“Alright” Erica said but walked slower than usual to the back of the store.

There was no one around when the two sisters came up “Hello” Rebecca said to the lady working “My sister and I would like to get measured”

“Of course…I’m here to help”

Erica was practically hiding behind her sister. She read the nametag that said ‘Barb’

“I said I’d go first…this is her first time so I wanted her to see and then she can have her turn” Rebecca said.

“Of course…I know it can feel embarrassing but it’s really no big deal. We’re all women here and it’s all very discreet” Barb said taking the tape measure from around her neck.

Rebecca stepped up and took off her bra.

“What size are you currently wearing?” Barb asked.

“34C” she answered as Barb wrapped the tape around her. She worked for just a few seconds before she smiled “Done! And I would recommend a 34D in all actuality”

“Oh ok…it has been over a year since I was fitted last” Rebecca replied.

“That’s why we recommend it every year…your body is constantly changing” Barb replied.

Rebecca stepped to the side and adjusted her clothing “See…it’s not that bad”

Erica was stone face as she stepped up. She put her arms out and closed her eyes. She heard a slight chuckle and felt Barb begin to measure her up “All done; you’re a 34A to start but you’ll need to keep a close eye on that. If your bra starts to feel tight, I recommend getting checked again. These years will have a lot of change”

“I wish they wouldn’t” Erica said “I wish I was just done”

“Not for a long time” Barb replied.

Erica and Rebecca headed out to the racks and started looking at styles and colors. Erica needed the basics so they grabbed white, cream and black to start. They took front clasp, back clasp and sports bra styles into the dressing rooms for her while Rebecca grabbed a navy blue that she knew matched a dress she had just bought.

“It’s empty…can you…can you come in with me?” Erica asked as they went to the dressing rooms.

“Oh…of course I can” Rebecca answered. There was a larger room at the end so that was the one they went to.

“Don’t laugh” Erica said as she took off her top.

“I would never laugh. You’re my sister…I was your age once, I know how this goes” Rebecca said.

“I just…I need some help” Erica admitted.

“That’s what big sisters are for” Rebecca said with a smile.

Erica put on the first bra and struggled with the back clasp. Rebecca showed her that at that size, she could spin it so she could see it to hook it and then adjust.

Erica blushed and tried the front clasp which was easier. “You can’t just stick with sports bras either. We are leaving here with traditional bras in your size”

As Erica tried on a few more, Rebecca took off her shirt and bra to try on one in her size.

“Damn” Erica said.

“You can easily make it to my size in time” Rebecca said as she tried on the navy blue bra. She posed and stretched her arms out. She was taking it back off when she said “I started out in a 34A myself”

“Ha! I’d love to see you try to wear one now” Erica said.

Rebecca felt a warm rush of mischief pass over her “Really…I’ll do it…I mean, no one’s watching”

“Yeah…do it!” Erica urged her on. “This is going to be hilarious!”

Rebecca couldn’t help but smile as she picked up the tiny bra her sister had just discarded. She hiked it over her shoulders “Oh God it’s tight already…I’m afraid I’m going to rip it”

“Haha just do it Becca” Erica urged her on “Do you need my help?”

“No…I think…” she struggled reaching up behind her “I…got it!” she managed to get it hooked “Oh Jeez…” she turned to face her sister and Erica busted out laughing.

The white cups were stretched out and barely covering her nipples. Rebecca’s breasts came out form above and below. She reached up to take it back off but Erica stopped her “Wait…just a second!”

Erica quickly picked up the navy blue 34D bra and tossed it on. She managed to hook it on the second try “Haha! Look at us! We can share bras now!” Erica said.

“Oh My God! We look ridiculous!” Rebecca said.

“Oh my gosh…what if they actually fit us…wouldn’t that be wild!” Erica added.

“I’d have to be 11 to have this fit me…that was the last time I was in this size” Rebecca said.

“And I’d have to be like 20 to ever get to this size” Erica sized up her tiny bumps inside the huge satin cups.

Rebecca shuddered.

The tiny bra was still super tight, but less flesh bulged out around it. She shivered as a chill passed over her “Oooo…wow”

“Are you okay Becca?” Erica asked. She was watching her big sister and didn’t notice flesh building up. Her skin stretching, her breasts growing into cone shapes slightly larger that actually came in contact with the edge of the bra cups.

“Yeah…I just a really weird feeling all of a sudden” She shuddered and shivered again “Oh! There it is again”

Rebecca’s breasts shrank down again. This time, the small bra shifted and caught more of her diminishing flesh. She looked down and a cold chill gripped her spine.

The back of her neck went numb, then burned hot “Something is wrong here” she said flatly.

“What is it?” Erica asked.

“Look down…my boobs…I don’t feel right and they don’t look right” Rebecca said.

Erica looked down “They’re small!” she blurted out.

Rebecca crossed her arms over top of them blushing and squirming. She could tell immediately that they didn’t feel as big “What’s going on?!”

“I don’t…Whoa!” Erica put her arm out to pat her sister on the shoulder and found that her arm it something on the way. She looked down and saw that her sister’s bra, the one that had been so huge on her seconds earlier was now half full.

Erica stagger stepped back. Her hands went up but stopped just short of touching her swelling breasts. They hovered as she made a high pitched squealing noise “EEENNNGGGHHH!!!”

Rebecca looked at what her sister was looking at and had to stifle a scream. “What the fuck is going on?!” she said, her eyes darting between her own shrinking breasts and Erica’s growing ones.

Erica felt her breasts brush against the front of the cups and her jaw dropped “I think our bras are going to fit us…our bodies are changing so the bras fit us”

“I’ll look like a freak! A no boob, flat chested…You’ll be quadruple my chest size! You’ll look like a freak! No 11 year old has a pair of D’s!”

“I don’t wanna be a freak Bec! Look at me!” Erica bounced and her chest took off. She slapped her hands on top of them and pressed down “Oh my gosh…I’m huge!”

“Calm down…we have to calm down and we’ll think of something” Rebecca said. “We’ll switch bras back and they can change back to normal and then we can forget this whole thing ever happened”

Rebecca reached up and tried to unhook the now fitting bra from her back but her fingers were shaking so bad, they kept slipping off.

Erica stood by unable to move. She nervously massaged her breasts before she felt a wave pass over her body which tensed up every nerve.

Rebecca felt it too. Her hands dropped to her sides and she flinched.

Rebecca turned slowly and faced Erica “Um…Ric?” she said in a shaky voice “I feel funny again”

Erica nodded “Yeah…me too” she let out a long slow breath not quite sure what she was feeling as her shoulders and back began to spread.

Additional weight began to appear on Erica’s body. Her hips shifted outward and her ass began to grow taking her thighs with them. Her legs were no longer girlish and coltish but rather becoming womanly and mature.

Rebecca shed pounds, her body thinned down to match her flat chest. Her ass flattened and her hips lifted up and inward, her thighs lost their curve and even her arms slimmed down. “What…? Erica?!”

Erica looked at her big sister who wasn’t as big. It wasn’t just that her chest was gone anymore; she was skinny now and something else “Rebecca! You’re shrinking!”

“What?!” Rebecca saw her sister’s face coming up closer to her own. She was still taller but barely.

Rebecca grabbed her sister by the shoulders and brought her up close. She ran a hand out from the top of her head straight across and only came up with an inch difference.

Erica had grown, but only 2 inches. Rebecca however had shrank down 3 inches on her own.

Rebecca’s jaw hung open in shock. Erica was wide eyed but Rebecca picked up subtle shifts in her sister’s face. “Oh my gosh…now what’s happening to us?”

Erica just shook her head.

Rebecca took her by the shoulders and spun her towards the mirror in their dressing room “AHH!”

Erica almost jumped out of her skin seeing her reflection “That! That’s me?!”

Her nose was bigger, her eyes wider set, her lips fuller, her chin stronger, her whole face was more mature “I look older” she said running her hands over her higher and stronger cheeks.

Rebecca leaned in closer as freckles broke out across her nose and cheeks. Her blue eyes narrowed and weakened as her cheeks rose up. Her lips thinned, her nose shrank down, and her chin came in “I look like a little kid!” she said in shocked awe.

Rebecca’s hair was still up in a top knot but it was lighter and looked thinner. Even her ears looked smaller.

Erica’s hair darkened and thickened and while still laying down, it became more layered and styled than it had and she gently ran her fingers through it.

The sight of her fingers caught her attention. They looked slightly larger but what really caught her attention was that her nails were manicured and looked nice instead of her usual half bitten nails with chipped cheap polish on them. They were a dark burgundy color and as she gazed past them, she noticed her toes were done in the same color.

“Whoa!” Erica posed her feet taking them in. Her flip flops looked to be a size too small and her heels hung slightly off the ends.

Rebecca’s brown sandals were a size too big for her now and she felt her feet slide as she tentatively moved around. Her sky blue polish was still in place but subtle changes had occurred. The polish was uneven on her bitten fingernails; heavy in some places and chipped away in others and on her feet, her second toes had no polish left on them at all and the other ones badly needed to be redone.

Her eyes traced up her skinny legs to her now baggy shorts. She could see clearly down as nothing blocked her view. She began to panic; nerves taking off and fear settling in.

Erica was calming down; she was confused but knew she had to take control of the situation. Her shorts cut into her sides and she grimaced as she undid them and took them off.

“What are you doing?” Rebecca asked.

“I can’t. I can’t wear these anymore…we’ve got to switch” Erica said.

“Oh…um…yeah sure” Rebecca replied and took off her shorts and panties easily.

“Thanks a lot” Erica said taking them and putting them on quickly. She saw Rebecca sliding into the smaller sizes just as effortlessly.

Before Rebecca could put her sandals back on, Erica kicked her flip flops over to her. “We need to switch these too”

“I…yeah, they did feel too big for me” Rebecca replied. The flip flops fit her better and the sandals were a perfect fit for Erica.

“What just happened? How did this happen?” Rebecca asked “We, like, switched sizes and then, like our ages?”

“Apparently so” Erica answered “I don’t know the why or the how of it. I was just joking around when I put your bra on”

“Yeah me too” Rebecca answered.

Erica took off the navy blue bra easily. She put on the cream colored one Rebecca had worn in along with her blue top “Let’s buy these and get out of here first”

“But…I don’t want to go out there looking like this!” Rebecca protested.

“We can’t stay in here all day!”

“Can’t we switch clothes back and try to switch back?!” Rebecca said.

“We can do it at home…that’s why I said we’ll buy these and then we can try again” Erica replied.

“How are we going to get home…I can’t drive duh” Rebecca said.

“No…but I can” Erica answered as Rebecca’s jaw dropped again.

She took off the 34A bra numb and put on Erica’s green t-shirt. “What the…how…?”

“I just can okay” Erica said taking Rebecca by the wrist and leading her out.

Rebecca didn’t fight it; she let her sister lead her out, her heart pounding as Barb walked up.

“So…how did those sizes work out for you two young ladies? See…it wasn’t that bad was it?” she directed her attention to Rebecca.

“Ha…you have no idea how bad it is” Rebecca replied.

Erica elbowed her “Don’t mind my little sister…she’s acting like a true tween today”

“Oh I deal with them all the time…it’s nothing new to me” Barb laughed “As long as you two are set, I can check you out at the registers right over here”

Erica had grabbed the purse off the ground instinctively, now she opened it and took out the wallet. She elbowed Rebecca and mouthed “Oh My God!” as she pointed to her driver’s license with her picture and name on it. She pulled out two credit cards that said Erica Thomas on them, stifling her smile as she used one to pay with.

They hurried through the store to the doors and once through, Rebecca exploded. She jumped up, her skinny little body hopping around like a frog “This is so unfair! How did you get my age and my cards and…and like, my knowledge on how to drive and do stuff” she whined.

Erica stopped by the back of the car “Look; if you want to drive us home go ahead” she dangled the keys but Rebecca kept her arms at her sides as her cheeks went red.

“Don’t pout…we’re going home to try and switch back so just get in the car and let me drive while I’m the adult between us”

“Ok Ric…” Rebecca said dejectedly getting into the passenger side.

They drove home mostly silent. Erica concentrating on driving yet marveling at how natural it felt while Rebecca examined her face in the visor mirror.

Once home, they dashed inside and ran to the family room where the blinds were still pulled shut.

“Ok…we need to try to do this like we were originally” Rebecca said.

“So should we switch our shorts and stuff back or start like this” Erica questioned.

“Um…let’s start like this and just put the bras on” Rebecca answered.

Erica pulled off her blue top and cream colored bra. She took the white bra out of the bag that had started all of this while handing the navy blue one to Rebecca.

Rebecca was clumsy with putting the bra on, like she had never really done it before while Erica struggled simply because of how small the garment was on her ample chest.

They stared at each other both realized they were holding their breath.

“I don’t feel anything” Rebecca said.

Erica shook her head “Neither do I”

“Shoot!” Rebecca said stomping her foot “Change your clothes with me…we have to be dressed just like we were”

Erica took off her shorts and panties and put the small ones back on, really sucking in to get them on. She even slipped her feet back into the flip flops while Rebecca put on her original clothes as well.

“I still don’t…” Erica said

“SHHHH!” Rebecca put her hand up “Don’t say anything Ric geez!”

Erica pursed her lips feeling the intense tightness of the bra strapped over her chest.

A full minute passed. Rebecca slumped her shoulders and sighed.

“I guess it was one way” Erica said. She popped the clasp and exhaled relieved. She stepped off the too small shoes and flexed her arms around “Can I take off your clothes?”

“What? What did you say? My clothes?” Rebecca replied looking at the discarded small sized clothes on the couch.

“Yeah…I said it. Your clothes…they don’t fit me and it doesn’t look like they ever will again” Erica said “I’m sorry” She grabbed up the original bra and top and put them on while Rebecca slowly took off her shorts and panties.

They redressed “I wish I understood what just happened” Rebecca said.

“And I wish we just both accepted it and could move on” Erica added.

Their eyes met.

A rush passed through them freezing them in place for a full minute.

“Whoa” Erica said shaking her head and laughing nervously.

“What…was…that all about?” Rebecca asked.

“Um…” Erica looked at her little sister “Something…”

Rebecca giggled and jutted out her hip “Yeah…I can’t quite put my finger on it but something’s different”

“I know…it’s like right there…” Erica said.

Rebecca looked at the new bras she had just gotten.

“You need to take those tags off and get them into the next load of laundry” Erica advised.

“Yeah…you don’t know who’s had these on before” Rebecca said picking them up and carrying them down the hall.

“I told Dad I’d make sure you got something to eat too before he got home. So do you want me to order pizza or I can take you to Subway” Erica said.

“Oh Subway…we had pizza a couple of days ago” Rebecca replied.

“Well hop in kiddo” Erica said taking her car keys back out.

“Thanks!” Rebecca said rushing past.

“What are big sisters for?” Erica smiled.