Only one month remained until Yang would begin her journey as a Beacon academy student. Her entire life up until then had been nothing, but looking after her little sister. She loved Ruby more than anything, as the little girl was all that remained of their mother. Sure Summer wasn't Yang's biological mother, but her kind nature was always something the blonde strived to become. Losing her was the hardest thing, the elder sister had to go through. However despite her loss, the brawler always aimed to be the best version of herself and to show Ruby the same love she once treasured in her brief time Summer. However, due to Yang's affections, it caused an aftereffect the blonde couldn't have accounted for. Ruby did love her sister, but the love certainly wasn't family friendly.

Late at night, Yang was on her bed and slowly regain consciousness as her body felt contorted, in such of an uncomfortable fashion. While her sight slowly returned, the first thing she notice was that her knees were bent, as her shin and thighs were tightly bound together by rope, and off to the side, she noticed little Ruby in her cute Grimm PJs tugging the straps harder. The busty girl, shocked at this event, raised her head a bit and attempted to speak, only to make an incomprehensible moan. Yang's alertness was quickly at a hundred percent as she could feel a cloth wrapped around her face as it dug into her mouth and in-between her teeth. She tried to sit up, but was equally as impossible as her hands were tied tightly by more rope and to make matters worse, upon looking downward she noticed her clothes completely off. All that remained was the rope around her legs and around her torso as to keep her arms from moving as well. Yang mumbled and moaned to get her sister's attention only for the younger one to giggle in response.

Ruby looked down on her victim and cooed, "Oh Yang, the drugs wore off at the best possible time. Now we can have some fun."

"Grraarr," The blonde grunted in confusion as that was the extent of her speech.

The younger sister leaned forward, face to face with her prey, "You see Yang, I've...Wanted to pleasure you for so long, that now that you're leaving for Beacon, I may not get another chance. You're so beautiful and loving and caring, that...I'm in love you Yang, but I know you'd never accept my advances willingly, so I had to be a little sneaky." Ruby placed one hand her sister's breast and continued, "So just lay back and try to relax and I promise when I'm done with you, you'll be craving my touch."

Ruby then dove her face into her sister's other breast, sucking on it oh so delicately while gently massaging the other. She made very small slurping noises, shifting from sucking to licking as Yang squeaked in ecstasy. The elder sister's entire face glowed bright red as she was helpless to her sister's molesting. After a few good seconds, Ruby commented, "Don't fret Yang, I know you're enjoying it. Your nipples are so hard."

The busty victim turned her head in embarrassment and shame, only for the captor to lift it back up so the two can meet face to face again, "Yang listen to me, you're the most important person in my life. It's okay to enjoy this, I'm doing this for you. I want you to know how much I love you."

Yang didn't know how to react, tonight she saw Ruby in a completely different light. Could she actually be falling her little sister? The dominant one smirked as she laid down next to her victim. She wrapped one arm around the blonde's neck to bring her in close and with her other hand, she snaked her way into Yang's nether regions. The younger one slowly massaged her victim's folds while dragging her tongue across her fuck toy's ear. She then moved onto gently nibbling the ear, all while listening to her prisoner let out low moans with every stroke. Yang laid back in bliss as her pussy slowly lubricated from Ruby's actions. The black haired girl sat back up and whispered, "Look at you, you're already wet."

Instead of shame, the blonde stared back at her sibling with passionate blissful eyes, as her love soothed. "Oh yeah, I can tell you want it now. Wait for just a second."

Ruby then got up from the bed and walked to the end of the room while removing her shirt. As Yang witnessed this entire act, she desperately wanted to gaze upon her lover's body, taking further pleasure as her sister slipped her pajama bottoms off giving full few of that cute butt. However Ruby slipped on something rather unordinary, it wasn't proper bottoms as it appeared, just above the girl's ass and on each leg were little straps that perked the cute cheeks up. Yang continued to stare as her sister turned to reveal a long rubber dildo sticking straight forward. The busty girl's eyes shot open as her sister giggled, "Oh yeah, someone's excited."

The dominant one swayed over to her sister's beautiful cunt, knelt down, and whispered, "Don't worry, I'll stick it in soon enough. Right now I want to taste you." Ruby leaned forward, her mouth inches away with her breath tickling the poor girl's pussy. Yang desperately wanted her sister's love, but was helpless to receive it. All the horny girl could do was wait as Ruby placed her tongue upon the lowest part of her sister's cunt and slowly dragged it across her folds. She continued these slow dragging sessions with her tongue being pressed deeper and deeper with every stroke until eventually her face was buried in puss. She then moved onto sucking upon the tiny little clit. Yang moaned as her legs twitched, the sensation was amazing as Ruby gave close attention to the little organ while inserting two fingers that slipped in and out with a wet swooshing noise. Swirling the little clit with her tongue, the younger girl broke off cooing, "I love hearing you moan, it's cute when you do that Yang."

The dominant reached over and pulled the cloth right off, giving her sister slightly more comfort as the poor girl panted. "Yang," Ruby hushed, "Say the word now and I'll untie you."

The blonde looked up at her love with fear in her eyes as the sister continued, "Or, beg me to fuck you and I'll make you cum your brains out."

With no hesitation whatsoever, the busty prisoner screamed, "FUCK ME Ruby pleeeeease, make me your bitch. I want you to pound my pussy."

"Good girl, just answer one question and I'll know if you're lying. How many guys have you slept with?"

Looked towards the side and a bit ashamed, she quietly admitted, "...One."

One, Ruby thought. Such a peculiar number, she was willing to share the fact she was not a virgin as little red always suspected, but why only one? Yang always had the party girl motif, always going out to social gatherings, and was very popular with the guys, but yet only one sexual experience? It would be suspicious if her sister admitted she was a virgin, but yet why reveal you weren't a virgin if you've only had one sexual partner? "You've...Only had sex one time?"

"...Yes, I was at a party as the designated driver for a couple of my friends. One guy I was really into for a while was just so sweet to me that night, so I followed him upstairs and the next day...He basically ignored me and started flirting with some other girl. To him I was just a prize, a goal, an achievement, I...Wanted more out of our relationship, but he wasn't interested in that. Afterwards, I found it hard to trust guys again. I could never tell if they interested in me as a person, but you Ruby...You love me and I love you. I'm gonna miss you when I head off to Beacon so...Let's make this month our month."

The younger one gave a little tear as she smiled, "Yang," she chirped as the rubber penis rested upon the girl's opening, "I will always love you."

And with one quick jerking motion, the appendage invaded the blonde's most sensitive area. Ruby began thrusting forward as her sister's eyes rolled back, her mouth giving off a wide open smile, and a tiny amount of drool leaked out. Little red rocked her lovers pussy over and over again thrusting harder with every movement. Yang squealing with ecstasy as pleasure sprang through her entire body. Ruby then became mesmerized as her lover's massive breasts flopping about, giving her a new found arousal, as she began thrusting harder to see those bouncing titties. Yang screamed louder with the increased speed while her sister's mouth watered at the sight of those glorious tits. Her pounding became so intense, the bed itself started to rock and slam into the wall as the busty girl phased in and out of consciousness until finally her cunt erupted with her love nectar, with one final scream. Ruby, exhausted from the work out, collapsed her face into those marvelous sweater puppies while both girls panted profusely.

Ruby, finally regaining some strength pulls herself away and reaches to the side. She pulls out a small knife as she carefully, but quickly cuts the small bounds from her sister's legs. This allowed the poor girl to feel a bit more comfort as the younger sibling then crawled to her side. "So Yang..." Little red moaned, "When...I start Beacon...In two years, we can do this again right?"

The blonde smiled at her lover and cooed, "Of course we can."

Ruby then leaned in and placed a small subtle kiss upon her lover's lips then whispered, "I'll be looking forward to it."

One month later

The two sisters were in a deep embrace as they both rode the airship to Beacon together. "I can't believe my baby sister is coming to Beacon with me," Yang cheered, "This is the best day ever."