New writer, want some critique

[D2og]

Hey guys. I usually commission what I want but lately have been thinking of trying my hand at writing something short. So I spent a hour in pastebin hammering this short chapter out. It's a generic role reversal type story. Really looking for a second pair of eyes to check out my writing style. Too verbose? Grammar is shit? Who knows? Not me. No real content to this chapter, just some basic scene building.

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"Sarah get your butt down here now!"

Sarah groaned, why was her sister always like this? At 15, she hardly needed her college aged sister to keep an eye on her for a week. Her parents were off on a second honeymoon, leaving her stuck with her demanding and bossy older sister.

"I'm coming Krystal!"

She took a quick glance in the mirror. Her messy brown hair desperately needed some quality time with a brush. Her light purple pajama set hung loosely over her thin frame. She cringed at her mostly flat chest, hoping to one morning awaken and be blessed with the amble bossoms her mom and sister shared. She turned away from the mirror to head downstairs to her impatiently waiting sister.

She found Krystal in the kitchen, her light blonde hair already neatly tied back into a pony tail. Her makeup was expertly applied despite there being nobody to witness it. Her clothes fit her toned body tightly, showing just a bit of her mid-drif. Standing next to Krystal always made Sarah feel like such a kid, even though only 7 years separated the two.

"Do you mind explaining this?"

Sarah followed her sister's finger to see it pointed at the kitchen sink, in which a single cup lie dirty.

"Yeah? And...?" Sarah questioned

Krystal scoffed, "I am not your mother, you know damn well how to wash your own dishes!"

Sarah couldn't believe it, her sister had screamed her awake because of a single dirty cup?

"I was going to wash it after breakfast! Besides, I washed up your dishes last night!" 

"Too bad I'm a guest. A guest that's stuck babysitting a child that can't do the most simple of chores properly" ,Krystal retorted

Sarah silently fumed as she pushed pass her sister to rinse out the solitary cup. She couldn't believe just because her sister was home for summer break she was considered a "guest". Only two days in to her week without parents and she was already sick of her sister bossing her around at every opportunity. She set the cup aside to dry and turned to face her sister.

"So any plans today?" She asked Krystal

"Not much, gonna hit up the mall for some light shopping. I could use a new summer outfit, maybe pick up a new bra or two" , her sister replied, not even glancing up from her bowl of cereal.

"Can I come? I have some allowance money and I really want to get a two piece bathing suit for the pool!" Sarah pleaded

Krystal laughed. "As if! The last thing I need is to get stuck carting my baby sister around while I shop. Why do you even need a two piece? You have nothing to show off anyway. Besides, I thought you were mature enough to stay by yourself? Isn't that what you cried to Mommy and Daddy about when they asked me to stay with you? Maybe in a few years, squirt"

Sarah bit back her tears. She was self-conscious about her lack of womanly development but didn't want to let on how much the comment had hurt, especially after being called the "baby" sister. Krystal stood from the table and dropped her dirty bowl in the sink.

"Ta ta baby sis, looks like you missed a few dishes by the way"

And just like that Krystal was out the door. Sarah felt so belittled, and ran to her room to cry. She wished to nobody in particular that her sister would get what was coming to her. She imagined tattling on her sister and having her parents take away her car. 

"That would show that bitch" She thought as she drifted back to the sleep she was awoken early from.

Sarah woke an hour later. She headed downstairs while checking her phone. Her sister had texted her she would be back in about another hour. Not wanting another confrontation, she headed to the kitchen to wash her sister's mess.

Just before she started washing it, she heard a soft knock at the door. Who could that be? She opened the door but saw nobody. Just as she was about to shut the door she glanced down to see a small package. Sarah picked it up and looked it over. There was no postage, no address, no identifying information of any kind except a neatly written "Sarah" in gold ink.

"I didn't order anything?" Sarah thought, as she brought the small parcel inside.

Walking to the living room, she decided to open it. Honestly she half expected a severed thumb or something else creepy, but inside all she saw was a cheap plastic ring, with a small piece of paper. She looked the ring over. It was a pale green and had no markings of any kind. It looked like something you would get for 25 cents from a vending machine. Idly slipping it on, she read the small note.

"Big sisters can be the worst. Wear this ring and maybe you can bring her down a peg...or three -LR"

"Huh, weird" Sarah thought to herself.

[WBDaddy]

Your grammar is clean, your sentence structures are clean, your formatting is clean.  That's a good start.

The downside is, you worked so hard at trying to make the big sister into Satan Incarnate that it's become cartoonish.  

I see why you did it, at the end, because you're setting up her being able to turn the big sister into a baby (what else could be the outcome on a site like this?)

Patience, my friend.  Patience.  You can create a much more compelling villain if you take your time with it, spend a few chapters creating believable scenes that still make Big Sis look like Big Jerk That Needs To Be Taken Down A Few Pegs.

[CutieButtCrusader]

I agree with a lot of what WBDaddy says.

Personally, I would like to know why Krystal is so antagonistic toward her sister. Sibling rivalry is a thing, but there's usually a motivating factor, like jealousy or resentment.