A/N: Warning and Disclaimer: I do not own RWBY or have rights to any of the characters in any way, and this contain mature content suited only for those 18+ in age. Also, this contains sexually explicit content featuring futanari, incest, and impregnation.
A Sister's Panties
Yang bit her lip, looking around to make sure no one seen her, before she reached into the laundry hamper, pulling out a pair of Ruby's recently discarded panties. Double checking again as she blushed, Yang slowly brought the white fabric to her face. She took a deep breath through her nose as she pressed it to the single red heart on the front of them, closing her eyes as she enjoyed the scent her sister left behind.
"God, what am I doing…?" Yang chastised herself, but kept on with her plans, slowly pulling her tightening panties off with her shorts. She sat down on her bed, pressing the fabric to her face again as she slowly wrapped the fingers of her free hand around her hardening shaft.
"I'm such a pervert…" She moaned lightly as she slowly rubbed herself, precum already leaking from the tip. Her pace increased a little as she smeared it on the palm of her hand, and rubbed it all over the tip, teasing it and the sensitive portion under the head with her fingertips. She closed her eyes, still breathing in her sister's scent as the shaft was gripped tighter than before. She imagined Ruby touching herself, getting the panties she was smelling dirty with her juices.
"Oh god, I can't imagine what she'd feel like." Yang panted lightly, draping the panties over her cock, before rubbing them up and down in rhythm to the daydream she began to have. Ruby was in nothing but an apron, back to her as her body was on display. Yang leaned her head back as she went further, grabbing her sister's ass and sliding inside her, stretching her virgin lips around her as she cried out in surprise and pleasure.
"Y-Yang!" Ruby would cry as Yang gave her no mercy, riding her as fast and rough as she wanted. By now the panties were starting to get stained with precum, Yang's tongue hanging out as she smiled, enjoying the fantasy.
"Oh wow..." Yang panted harder, biting her lip as pressure started to build, leaving her on the verge of orgasm. She squeezed her eyes shut as she felt her balls tightening, desperate to fill the Ruby of her fantasy.
Unfortunately, the real Ruby came back for her forgotten homework at the most inopportune moment possible. Her eyes widened as she saw what her sister was doing, before crying out in surprise as the warm, sticky fluid shot onto her face and breasts, with a little landing in her mouth as she fell back onto the floor.
"Ruby!" Yang's eyes widened as they snapped open, watching the whole ordeal as it unfolded. She couldn't help but fall back onto her elbows, panting heavily. Despite the powerful orgasm she just had though, her member didn't shrink in the slightest. This was most likely due to the incredibly hot image in front of her of Ruby undoubtable tasting and swallowing the cum that got in her mouth as she gave short, cute pants, staring back at Yang.
"You could've gave me some sort of warning..." Ruby said, surprisingly calm.
"I, uh..." Yang gaped at her, blinking several times as Ruby wiped the cum onto her fingers, before licking them clean in front of her.
"Tastes different than I expected." Ruby mused, seeing her sister's predicament. "Can you take care of that on your own?" She said as she got up and sat next to her sister, smiling innocently as she poked it. Yang blushed, just nodding.
"Did Blake teach you anything about this? Because if she did I'll-!" Yang was muffled as Ruby suddenly kissed her, quickly pulling back and smirking.
"Try not being so loud when you're playing with yourself late at night." She pecked her cheek, before walking over to her bag and bending over, looking through it for her paper. Unfortunately, this also gave Yang the perfect view of her panties under the short uniform skirt.
"They really should make the skirts longer..." Yang said as she got up, putting her hands on Ruby's butt and pinching it, making her squeak in surprise.
"Yang!" She blushed, turning her head.
"What?" Yang smirked, starting to rub herself slowly against her sister.
"Come on, I have to get back to class..." She groaned, face reddening as she felt herself starting to get wet.
"Mm, I don't think you're gonna be going back to class for a while~" Yang grinned as rubbed against her panties, making Ruby try and fail at hiding the cute noises she made. The young girl shivered lightly as the only barrier in Yang's way was slid down her legs.
"Can't it wait until later?" She bit her lip. "You just came all over me..."
"That's exactly the issue..." Yang teased her, first by jabbing lightly with the tip, before rubbing the shaft against her lips. "Now I won't be satisfied until I hear you begging me for more." She rubbed the head against her lips, finding where to push in.
Yang turned Ruby's head towards her, looking into her eyes as she leaned forward into a kiss, both of them moaning into it as the younger girl slid her tongue against her sister's lip, before slowly slipping it in further to explore. Yang smirked, pushing on the back of Ruby's head as she deepened the kiss, rubbing her tongue against the other's.
Seemingly too soon, Yang pulled out of the kiss, a strand of saliva hanging before them for a moment as she licked her lips, smiling. "It may be wrong...but I love you, sis." Ruby stood up straight and took Yang's hand, leading her over to Weiss' bed. She laid back onto it, pecking Yang's cheek as she pulled her along.
"Let's see if you love me as much as I love you." Ruby hooked her arms around Yang's neck, smiling nervously.
"Don't worry, I'll be gentle." Yang put her hands on Ruby's shoulders, before kissing her nose. Ruby rolled her eyes, smirking.
"We both know you're gonna make a mess of me." Yang pecked Ruby's lips.
"Sorry in advance then…" She said as she slowly started to slide it, taking care as Ruby's grip tightened as she was spread, panting lightly.
"Oh Yang..." Ruby closed her eyes as her hymen was pressed against. "Just do it..." Yang cupped Ruby's face, kissing her deeply as she slowly pushed though. Ruby's quiet cries were muffled completely as she kissed back, a few tears squeezing out that Yang wiped away. The smaller girl couldn't help but shiver as her sister bottomed out inside her.
After a lying like that for a few minutes, waiting for Ruby to adjust, Yang started to move slowly.
"Ugh, Yang..." Ruby groaned, moving her hips a little. "I'm not that delicate..."
Yang started slowly speeding up, frustratingly slow to Ruby, who started to buck her hips. Yang bit her lip, panting heavier as she got the point.
"Oo, yes..." Ruby moaned, closing her eyes as she began to part as well.
Yang kept speeding up, working up to the pace she wanted, making the girl underneath squirm and gasp as her eyes rolled back, tongue hanging out.
"Ruby..." Yang grit her teeth, feeling her balls start to tighten. "I'm not gonna last much longer..."
"Me neither!" She cried, her face going ahegao. "Go ahead, cum inside!"
"But you'll get pregnant!" Yang bit her lip, trying her best to hold on.
"I don't care! I want you to fill meeee-Ah!" Ruby suddenly tightened around Yang as her member was coated in her juices, pushing the blond over the edge.
"Ruby!" She cried as she slammed against her, pumping her hot, potent load into her. She kept bucking, instinct making her try to force as much as she could inside, desperate to fill her young, defenseless womb.
Yang gradually slowed to a stop as her orgasm, mind blank except for the incredible pleasure she just felt.
"Oh my god..." Ruby panted. "It's so hot and full inside me..."
"You're...gonna get pregnant for sure..." Yang fell limp beside Ruby, her softening cock slipping out. Cum started leaking out of Ruby slowly, but continuously, showing just how much had been pumped inside.
Yang wrapped her arms around Ruby, making her giggle as she showered her in kisses.
"We're really gonna have a baby…" Yang mumbled as she settled down, cuddling Ruby.
"Yep." Ruby smiled wide, kissing Yang's nose. "But it'll all work out." Yang smiled a little at this attitude, wrapping her arms around Ruby a bit tighter.
"I love you Ruby…" Yang pressed her lips against Ruby's, making her giggle as she kissed back.
"Love you too, Yang."
A/N: Thanks for reading, and I hoped you enjoyed. As always, feel to leave a review with constructive criticism, or just tell me what you enjoyed the most. Also, I'm now open to suggestions via both pms and reviews. The former is preferred if you have a more detailed idea. And happy holidays all.