Ruby Rose, Her New Cock, and an Ero System (A LitRPG RWBY AU)

12. Problem Solved

Ruby made it through the night, but it wasn't pleasant, spending most of it tossing and turning, an aching erection plaguing her.

Spars the next day were difficult to stay focused on, to say the least. Ruby found her eyes gravitating toward Yang's curves in a way they hadn't even back in the Rift, when the two of them had been naked. Ruby kept chiding herself for her wandering eyes, but she couldn't help herself. Not with that pressure mounting and mounting, the desperate need for release starting to take over her thoughts. She didn't even think the Pink Dust was causing the arousal, just that it stopped her from acting on it, and thus the pressure kept growing.

Eventually, her sister caught on.

"Nah, seriously, Rubes," Yang said. "I can tell something's up." She raised an eyebrow. "I know I have nice tits, but you've been staring all day."

The attempt at levity only had Ruby's face burning hotter. And despite just being accused of doing so, at the mention of her sister's 'nice assets', she couldn't help but steal another glance. Her skirt swelled up, announcing her approval, and Ruby felt dizzy with mortification. Yang's eyes flicked down, making it clear she'd caught the reaction.

"Is it the Pink Dust from yesterday?" Yang asked. "It did something, didn't it?"

Ruby wasn't surprised Yang had sussed out the source of the issue. However much she could be loud, brash, and thus assumed not the smartest girl, Yang was plenty intelligent. When she wanted to be, at least.

Ruby swallowed. "I, um, did find out what the effect is," she said lamely. "But don't worry about it. It's my issue."

"It's our issue," Yang disagreed flatly. "Or are we not sisters anymore?"

That was kind of the problem. Them being sisters. "It's for me to deal with, Yang."

"I'll be the judge of that," Yang said stubbornly. "Tell me what happened."

Ruby could tell by the set of Yang's jaw that this wasn't a conversation she'd be wiggling out of. But really. How horrifying to have to explain. She glanced away, forcing herself to work up the nerve.

"So… basically…"

"Yeah?"

"I… can't touch myself." She winced as the words came out.

Yang blinked, digesting the announcement. "You mean like—"

"Like that, yes."

"Oh." She was quiet for a few seconds. "That explains a few things."

Like why Ruby was so pent up, she didn't say aloud.

"And you still can't?" Yang asked.

"It's ongoing, yes."

"Have you tried—"

"I've tried everything," Ruby said, interrupting her. "We don't, um, have to grow through a list. Brainstorm ideas. Already did that. It's magic, and it always stops me." Face burning like the sun, she said, "But like I said, it's my issue. You can hardly help with it."

Yang opened her mouth, then closed it. A blush rose on her own cheeks, and she looked away. "Right," she coughed. "That sucks. It'll probably expire eventually, like the outfits do?"

One could hope.

Without much more to say on the topic, they got back to sparring.

A timer. Would the effect run out on a timer, though? Or was the expiration decided by something else? She had a theory for what was actually required. But she really, really hoped that wasn't the case. Because who could she find to help with that sort of problem, if the effect only expired when she'd 'gotten outside help'?

The second night was worse than the first. Ruby suffered through, mostly because she didn't have a choice in the matter.

It became apparent that it was going to be a problem, though, because the next day, Ruby was sporting an erection more often than she wasn't. Somehow she managed not to blow her cover, but only because she spent most of the day training with Yang and away from the house.

Her only salvation came through distracting herself, so she devoted to training for the upcoming qualification exam with even more razor focus than she usually mustered—and Ruby was already a girl highly focused on her future. But in the end, even that was only a bandage.

On the third night, Ruby found herself lying on her bed, glaring at twelve inches of cock, cursing it for the way she hadn't been able to think straight for days now. A bead of precum was at the tip; a shiny trail led down the front from an earlier leak.

If only she could touch it. It was maddening how badly she needed to. But no matter how hard she tried, she just couldn't. So once again, she tossed and turned, trying to sleep, and failing that too.

Some time later, a knock came at her door. Ruby froze. This late, it had to be Yang.

"Come in?" she offered.

Sure enough, it was Yang who cracked the door open and slipped in. The first thing her eyes landed on was Ruby's face, but quickly flicked down to her crotch to see the bulge there. Ruby had tried to cram her cock into her pajama pants in a way that it wouldn't be obvious, but it was simply too big to hide.

"Still going on, huh?" Yang asked.

"Um," Ruby said. "Yep."

Yang sat next to her, and Ruby shuffled up to lean against the headboard. It made the imprint of her cock slightly less obvious.

"Alright," Yang said. "Something needs to be done."

"There isn't anything that can be done," Ruby said, rubbing her face. "I told you that already. Just have to wait it out."

"It's been days. I don't think it's going away. Not by a time limit, at least."

Ruby had already guessed that much too. It wasn't surprising Yang had drawn the same conclusion.

"And we'll be heading to Vale tomorrow," she continued. "To Beacon. You might be able to get away with hiding that thing right now, but not then. We'll be out in public too much. Not to mention, you can't afford to be distracted during qualifications."

"There isn't anything to do," Ruby repeated.

"Well," Yang said. "Maybe there is."

Ruby's brow furrowed, not understanding right away.

Then Yang placed her hand on Ruby's thigh.

She froze. The hand started sliding upward—slowly, as if to give her time to say something. But she didn't. Was unable to.

Yang's hand slid onto the head of her cock, resting against the imprint down near her knee.

Her sister's hand was on her cock.

What—

What was Yang—

"You just can't touch yourself," Yang said matter-of-factly. "Which means you need someone else to do it. Right?"

"Y-Yang?"

Yang shrugged, somehow as casual as always. Even when her hand was on her little sister's cock. Lilac eyes met Ruby's easily, not shying away. Confident as always. Though she was at least blushing, not as noticeable in the dark, but still obvious. Not as badly as Ruby was blushing, though. In only seconds, her heart felt like it was going to jump out of her chest.

"Something needs to be done," Yang repeated. "And it's my job as your big sister to be there when you need me." She squeezed Ruby through her pajama bottoms, wrapping fingers around the top of her shaft and head, squeezing fabric around and grabbing a firm hold. A whining noise escaped from the back of Ruby's throat—and was loud enough to make them both freeze.

"But, ah," Yang said, glancing at the door. "You'll need to be quiet. Don't wanna wake anyone up."

"S-Sorry."

Yang scooted up the bed, situating herself better. "Lay back down. We'll get this taken care of in no time."

***

Yang watched as, after a short hesitation, Ruby obeyed, sliding down so that she was lying on her back. The angle had the bulge in her pajama pants sticking up in a much more noticeable manner, straining the clothing, lifting the waistband several inches from Ruby's skin. Without being told to, Ruby hooked her thumbs into her pajama bottoms and pulled—sliding the fabric to her thighs, freeing its twelve-inch prisoner. Yang herself nearly froze at that, at how quickly Ruby had ceded to this idea. She must badly need help, to barely have hesitated.

Yang's head had already been fuzzy, but seeing her little sister's cock standing straight up, veiny and aching and leaking precum, had her entire body flushed. Her little sister had just exposed her cock to her. And was now waiting for Yang to take care of her.

Was she really doing this?

Ruby needed help. That was genuinely true. But still. This kind of help?

She was going to jerk her little sister off?

Her hand moved of its own accord to wrap around the base of Ruby's cock, scooting in closer, thigh pressing into Ruby's—which answered her own question.

Yes. Yes, she was going to jerk her little sister off.

A thrill coursed through her at the realization, only half because she was touching Ruby's cock, but also because of the little whine that came out of her. It was somehow the cutest, yet hottest, thing she'd ever heard.

Yang had done that. She'd made Ruby moan in pleasure.

Her last hesitations faded away. She shuffled her way up and onto Ruby's lap, sitting on her thighs, legs to either side of Ruby. She grabbed Ruby's cock with her second hand, so that she had a firm two-handed grip on twelve monstrous inches of girlcock.

"Seriously," Yang whispered with a soft, incredulous laugh. "Why does my little sister have such a huge fucking cock?"

"Um," Ruby replied in a squeak.

"It's a compliment," Yang reassured her, squeezing and making Ruby arch her hips upward. With Yang sitting on her thighs, the movement lifted her an inch up. "You're gonna make some girl very, very happy one day, Ruby."

She started to stroke.

No going back now, she thought with faint amusement. She was actually doing it. Not just holding Ruby in her hands, but actually jerking her off. Hands going up and down her giant fucking cock.

It was hot to the touch, and the clear bead of pre-cum that had formed at the tip quickly coated Yang's palm as she rolled her fingers around the tip, making it easier to slide up and down the shaft. And Ruby was really leaking, which made for easy lubrication. She'd been pent up for days… and seemed to have more of a libido than the average girl in the first place, thanks to this new addition of hers.

"Yang…" Ruby murmured.

The word came out as a breathy whisper, a hidden please behind it, and something hot coursed through Yang, making her stomach clench so hard it surprised her. All at once, her heart was pounding in her chest.

She tried to ignore her arousal—the fact she was wet for her little sister—and focused on the task at hand, telling herself that this was simply another one of Ruby's problems that she was helping with. Nothing weird about it. Her sister had always come to her with scraped knees and school woes and the like, and this time, what she needed help with was just... a little different.

"Feels good?" Yang murmured. "You like it?"

She had intended to be quick and professional about this, to be the helping hand—pun intended, puns were awesome—that Ruby needed, but the question left her unbidden, and ten times huskier than intended.

"Yeah," Ruby stammered. "Your hands feel… feel really good, Yang."

Lewd, slick noises filled the air as Yang's grip traveled up and down her cock. She found it harder and harder to ignore the way her breath was quickening, the way her body was responding to the lewdness of what she was doing. Responding to the feel of Ruby's length in her hand, to the powerful, virile heat of her sister's cock as it twitched in her grip.

Yang found herself scooting up Ruby's legs until she was sitting fully on her lap. She pressed Ruby's cock toward her stomach until it was lying flat against her. It stood up well past her belly button. She knew even as she was doing it that she shouldn't, that laying her sister's cock out against her in such a way was crossing a line—but there she went anyway, body moving of its own accord. Pressing that hot mass in until it was pushing against her pussy and stomach.

"That's how far you'd reach," Yang murmured. "Look at that."

Lost in the moment, she didn't realize what she'd said, and implied, until she looked up to see Ruby's wide silver eyes, the beet-red coloring of her face.

"Um," Yang said, freezing as she came up with a way to salvage the words. "I just mean—it's so big. I almost can't believe it."

She hadn't been implying she would let Ruby put it in. Just that if she did, her sister's twelve inches would fill her up so completely she might lose her mind. Stir up her insides in a way no one else, maybe literally, ever could.

Yang specifically stopped thinking about that. About how deep her sister would reach if, say, she lost control and pushed Yang over, needing more than just hands to pleasure her.

Still trying to save herself from her misstep, Yang searched around for something to say.

"You know," she said. "We don't actually talk about girls that much. There's gonna be lots of options when we get to Beacon, yeah? And you're gonna need help with this thing," she joked, squeezing. "So what'cha looking for in a girlfriend?"

"Um," Ruby said—and Yang realized maybe this was an awkward question to bring up while she was sitting on Ruby's lap, running her hands up and down her cock. "I don't know? S-Someone nice? And pretty?"

Yang laughed. It was a typical Ruby answer, generic but probably honest. "I mean, what gets you going?" She squeezed Ruby's cock in emphasis. "Butt? Legs? Abs? How big do you like your boobs? Gimme the details."

On that last question, Ruby's eyes flicked down to Yang's breasts. Her nipples were hard, and, in the loose tank-top she'd worn to bed, visibly poking through the fabric.

"A-Any size," Ruby stammered. "But big are… um, big are fun."

Yang smirked. The hidden compliment was obvious: Ruby was saying her big sister's tits impressed her. Yang couldn't help but preen at that.

More lewd sounds filled the air as Yang continued jerking Ruby off.

"I thought you were pent up," Yang said. "But you're holding off surprisingly well." Ruby had seemed like she'd been going crazy, to the extent Yang had expected to touch her and have her all but instantly explode. But it'd been several minutes now.

"It feels really good," Ruby admitted. "But I don't need to…finish yet."

"Just enjoying yourself, huh?"

Ruby blushed, but then nodded.

"Giant cock and the stamina to go with it," Yang tutted, shaking her head. "No kidding, you're really gonna make some girl's year at Beacon."

Would make my year, if you wanted to.

She cut that thought off.

Despite Ruby's squirming and hard breathing, she honestly didn't seem that close to climax yet. Yang hesitated as an idea hit her. "Maybe you need something to look at? To help you along?"

Ruby gave her a confused look.

Without explaining, Yang slipped off her tank-top, casual as could be, tossing it to the side. "So we're not here all night," she found herself saying—and a part of her recognized it as an excuse. She had just wanted to see Ruby's eyes lock to her exposed chest. To her nipples. To feel Ruby's cock throb in her hands in plain arousal at seeing her big sister's tits.

Lusting over her.

Just like she was lusting over Ruby.

Oh, gods, this was so wrong.

She slid off Ruby's lap and lay down next to her, stroking with one hand, propped up on an elbow so that her breasts were in Ruby's face.

"Well?" Yang murmured. "These help? I'm not tryna be here all night."

Ruby's body answered the question for her—she started to buck into Yang's hand.

"O-Oh," Yang said, surprised. "Yeah, okay. Um. You getting close?"

The words came out breathy, and she felt her face flush as Ruby's head fell back into the pillow, eyes squeezing closed as a groan escaped her. After a second, she forced her eyes open and back to Yang's chest—obviously not wanting to give up the sight of her tits.

Her little sister was getting off to her. The thought sent a thrill right to her core. Yang struggled to moderate her own breathing, to not seem too blatantly excited at what she was doing. Purely a professional job, this, she reminded herself.

Yang's eyes dropped to Ruby's cock, watching it twitch and jerk, throbbing with urgency as Ruby slowly ran up to that cliff. Yang was transfixed for a moment before she forced herself to meet Ruby's eyes again, seeing the same rapt attention reflected there. Ruby's breath hitched, and her eyes fluttered closed, seeming like an omen this time. Her lips parted as her whole body started to tense. Not there yet, but getting close. A much louder, breathy moan escaped her, a noise Yang had never heard before—a sound of bliss.

Her hips really began to pump into Yang's grip, making the mattress bounce. Her breaths came in short, stuttering gasps, and her whole body trembled with the effort of holding back.

Yang sped up, tightening her grip, and with her free hand, she reached down to cup Ruby's balls, now drawn up tight against her body.

Close. Very close. What was she fantasizing about, right now, Yang wondered?

"Yang…" Ruby whispered.

"Go ahead," she murmured into Ruby's ear. "Come for your big sister."

Those words definitely hadn't meant to slip out, but they did—and they broke the dam in an instant. Ruby's body went rigid as a strangled whine escaped her. Her hips bucked wildly, the muscles in her thighs and stomach tightening as her cock throbbed in Yang's fist.

And finally, she came.

She shot rope after rope of hot, stringy cum into the air. Some landed on Yang's hand as she pumped, the motions desperate, somehow as eager to get Ruby off as Ruby was to get off. Some of the sticky material hit Ruby's stomach and chest, and the rest, well, went everywhere. Yang probably could've controlled the collateral damage, but she didn't. Too caught up in the moment.

Too caught up in milking her little sister.

The sight of it had Yang feeling faint. She couldn't believe how turned on she was, seeing Ruby lose control. It was the hottest thing she'd ever seen, bar none, and it left her trembling almost as much as her partner.

When it was over, Yang lay down at Ruby's side, cuddling in, her sister's release coating her hand, warm and sticky. Ruby's body relaxed into the bed, breaths still coming in gasps. As she came down from her high, Yang realized—fully—what she'd just done. In the moment, it had been different, but now it was over.

She had jerked off her little sister.

Oh, gods.

"Well, there we go," Yang said, her voice impressively unflustered. "Problem solved."