Sweetie Belle stood on the steps and gripped the railing, her nails digging into the paint. She said nothing, silently glaring at Button with an expression somewhere between a frown and a pout. Her white cheeks were flushed with color, which Button thought made her look very pretty along with her emerald eyes.
Button took a step back, unthreading his cock from the pretty girl’s elder sister, drawing out one final moan from Rarity that made Sweetie’s brow twitch.
Rarity turned over and propped herself up on the back of the couch.
“Ah, Sweetie Belle…” began Rarity, then her breasts slipped out of the loose armholes of her shirt to hang over the edge of the couch.
Sweetie Belle covered her eyes with her hands. “Oh my gosh, Rarity!” she cried, her voice cracking. “Cover your boobs!”
Rarity frowned and looked down, then tucked her breasts back into her shirt and sat back onto her heels, a dollop of cum leaking out onto the cushion between her legs.
Sweetie couldn’t believe what was happening. She knew Rarity was going through something, but she never expected her to do something like this. She wanted to run back upstairs and pretend she hadn’t seen anything, but another, stronger part of her felt that she needed to confront this here and now.
“And you, Button Mash! Put your pants back on!”
Button scrambled to recover his pants, suddenly feeling very silly standing in the open with his penis out.
Rarity pushed off from the couch, sliding off the cushions and standing up straight. She felt a pang of guilt, seeing her sister so upset, and realized that perhaps she had gone too far. After all, the last thing she wanted was for her sweet little sister, who used to hang onto her every word, to be disgusted by her.
Still, the past could not erase the pain of the present. She was frustrated with, well… with everything. She didn’t even know how she was going to finish out the year. She felt like she missed her chance at happiness, as though her destiny had passed her by and left her behind.
Whenever she began to think about any of it her mind locked up, and she could focus only on finding something to help push it all away, be it food, alcohol or (apparently) her sister’s classmate.
What a sight she must be for her sister, who will be deciding what direction she will take after her upcoming graduation. She didn’t want her sister to think that this is the fate that awaited her.
Then, with all that swirling in her mind, Rarity began to cry.
“I’m sorry Sweetie Belle. I’ve been a terrible sister.”
Sweetie opened her eyes and looked down at Rarity, unable to hold on to her anger while her sister was in such a sorry state.
“I don’t know what I’m even doing anymore. Nothing has gone the way it was supposed to, and I can’t seem to fix it. All I’m good at is running away.”
Her mascara began to run, and Sweetie made her way down the stairs as Button stepped back, feeling like he didn’t belong.
“Oh Rarity… I didn’t know.” said Sweetie carefully.
“I didn’t want you to.” Rarity replied. “I didn’t want to scare you.”
Sweetie Belle smiled softly, then pressed herself close to her elder sister, feeling her warmth as she placed her arms around the taller girl’s waist, looking up at her teary eyes over the shelf of her porcelain breasts.
She reached up and let Rarity rest her cheek in her palm. The older girl closed her eyes and nestled into her little sister’s touch.
She noticed that Sweetie’s perfume was different than usual; mature yet much more pleasant than the fleeting traces of alcohol that haunted Rarity of late.
Sweetie Belle traced the seam of Rarity’s lips with her thumb, then pushed it inside. Her finger was wet when she withdrew it, allowing her to wipe the mascara from her sister’s cheeks.
Rarity was about to speak but Sweetie placed her index finger over her lips, then raised her ring-finger as well and pressed them both forward until Rarity let them in, sucking on them as Sweetie caressed her butt with her other hand.
Sweetie’s nipples were hard as ice, like little glaciers atop hills of fresh snow, hidden beneath her shirt. Rarity could feel them pressing against her, and her own tensed up in response, catching Sweetie Belle’s eye and drawing her mouth to them, the suction of her lips and the flicking of the tongue providing a controlled yet dynamic pleasure.
When she was done suckling at her sister’s teat, Sweetie lifted her shirt and shrugged it off, tossing it aside so that it landed directly on Button’s face.
Her scent overwhelmed Button Mash’s senses, and though he couldn’t see, Button instantly got hard and was hesitant to take it off. Yet he wanted to watch the scene between the sisters unfold, so he grabbed the shirt from his face, wrapping it around his penis and using it to masturbate as he looked on with wonder.
Rarity was a little unnerved by how much she was turned on by her sister’s little breasts, and nearly melted has Sweetie guided her hands to them, placing her thumbs over the nipples.
Sweetie bit her lip when Rarity flicked them with her nails, then let out a gasp of hot breath which Rarity caught in her mouth as she leaned down and planted a kiss on her sister’s lips.
Button let go, his flared dick pulsing, shooting strings of thick cum like chain-shot from a cannon that draped themselves over the two sisters, catching in their hair and on their clothes.
When he was finished he saw Sweetie staring at him and tried to back away, but was driven against the wall.
“You still have to pay for your part in this.” said Sweetie Belle, wiping the cum from her face.
Author's Note
I began writing this a while ago but wasn’t certain where I wanted it to go, so it sat unfinished for some time. 
Hopefully it is enjoyable, I had fun writing it, especially toward the end. 
