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

11. Experimentation

For their first practice session back in the real world, Ruby and Yang trekked out into the forest. That wasn't all that uncommon to begin with, since when it came to testing explosives, being far away from people was only smart. There were arenas and facilities that could contain the dangerous forces associated with huntresses—whether bullets or semblances or whatever else—but those were public settings, as a whole. At least the ones they could afford. And the two of them needed privacy, seeing how they would be experimenting with Pink Dust.

Ammo was no longer a problem; they had stocked up before heading out. Not that they had infinite amounts to go around. Dust was expensive. Still, practice was important, especially since they were cramming for Beacon's entrance exam. But neither Ruby nor Yang could afford to fire their weapons to their heart's content.

"Alright," Yang said. "So, Pink Dust. What are our theories?"

"For why none of my shots during the E-Rank fight had a side effect?"—Yang nodded—"Well, I've got some ideas." Ruby chewed on her lip. "It's either that it's rarer than we thought, and we just got unlucky on the first try. Or other factors influence it."

"Like what?"

"Maybe it reads the situation?" Ruby suggested. "That sounds silly, I know, Dust can't think. But I've got this hunch that since it was a life or death fight, the Pink Dust responded to our emotions and didn't, you know—do anything weird. Because it wouldn't have been the time." She shrugged. "I've got a gut feeling telling me that's what happened. Maybe from my class. And I'm also pretty sure something is gonna happen the very next shot, because there's energy 'stored up' from that fight, and it needs to be released."

Yang raised an eyebrow. "Well, you won't catch me dismissing a hunch. Sounds weird, but I trust you." She deployed Ember Celica, the weapons folding out into their gauntlet forms. "Think that 'stored up energy' is independent to each person, or is my next shot guaranteed to do something, too?"

That was a good question. Yang had, of course, mixed in pink dust into her bullets as well. The amplification was too powerful to not use, regardless of the side effects. So long as they were in private, at least. Being thrown into a lewd bunnygirl suit in the middle of Beacon's qualification exam might be…a little much.

"I think it carries over to you too?" Ruby hedged, uncertain. "Maybe it's group based. I've got a feeling it'll count for you, but that might only be because I'm with you, right now." She tilted her head. "You wanna start us off?"

Yang snorted. "It's your turn to have a 'side-effect', don't you think? Least with our sample size of one, Pink Dust affects the opposite person. So yeah, I'll go first. Plus, I wanna test the theory. See if the stored up energy counts on me too." She pointed Ember Celica toward a nearby tree. "Ready, then?"

Ruby swallowed, mentally bracing herself for whatever might happen, then nodded.

Yang fired.

Her hunch turned out correct. Despite the shells in Yang's shotgauntlet having been loaded with a relatively small amount of Pink Dust, a secondary effect triggered on the first shot. Ruby was engulfed in an explosion of pink smoke, vision briefly obscured.

When it cleared away, she looked down at herself, ready for anything.

A bikini?

Her huntress outfit had vanished, and now she was wearing a bikini. Not just any old swimwear either; that wouldn't be so embarrassing. Rather, it was the skimpiest, thinnest bikini she'd ever seen. The bra barely covered anything—only slightly more than her nipples, but otherwise leaving all the curves of her breasts on display. And her butt wasn't much better concealed.

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And, of course, there was the biggest problem. The bra up top was at least doing its job in some nominal manner. Downstairs, on her front? Not so much. Her bulge was extremely noticeable.

Aghast, she looked up. Yang was staring at her, both her eyebrows raised. Her attention raked up and down Ruby's body, taking the new outfit in.

Which made things go from bad to worse. Knowing that she was exposed, and that her sister's eyes were running across her, Ruby's body reacted. Already she hadn't fit inside the bikini's bottom, so as she started to stiffen, the end-result was inevitable: Ruby's swelling cock popped out, hardening upward until twelve inches of girldick was lying flat against her stomach, the bikini bottom now just acting as a way to cup her balls and hold her cock up.

Yang had frozen as the change took place, but finally she wrenched her eyes up to meet Ruby's. At least Ruby wasn't the only one blushing now.

Ruby also spurred herself into action. She spun, turning her back to Yang, hiding her erection from her sister. Though she supposed that just meant she was showing off her ass now.

"Well," Yang said, though despite the bright blush on her cheeks, she sounded more amused than flustered. "At least we know it's not gonna be a bunnysuit every time."

"What the heck," Ruby squeaked. "This covers, like, nothing!"

"Probably the point," Yang laughed. "Man, it's especially mean to give you a bikini when you're packing that much heat. Does literally nothing to hide it."

Ruby tried to ignore the fact that her sister had just said she was 'packing heat.'

"Turn around, Ruby," Yang said, and she could hear the roll in her eyes. "This is obviously something we have to get used to. And, sheesh, it's not like I didn't see plenty of that thing already. Spent a whole day with you naked, didn't I?"

That was true, she guessed. If not doing much for her embarrassment.

"And it's stuck on you for at least half an hour, if the bunnysuit was anything to go by. We're not gonna try to wait it out, are we?"

No, she was right there too. That would be a huge waste of time, and they had training to do.

With burning cheeks, Ruby faced back forward. She ignored how Yang's eyes flicked down to her exposed cock, still sticking up and laid flat across her stomach.

"Alright," Yang said. "That's also confirmation for your 'build up' theory. Pink Dust will try to find opportune moments to trigger, like when we're practicing. Or in less deadly fights against regular Grimm, where there's less threat." She tilted her head. "Wouldn't totally count out the possibility of something happening in an important fight, though. Low sample size and everything."

"What if we use too much of it?" Ruby asked. "If the pressure built up too much? Would something happen, regardless of it being 'inopportune'?"

"Also a good point." She shrugged. "We'll find out, I guess. Is there still pressure left, or did we clear it out?"

Ruby hesitated. "There's more."

"Let's get that over with, then. Time to find out what skimpy outfit I'll get," she said sarcastically. "Better to be embarrassed together, I suppose."

Ruby summoned Crescent Rose. The giant sniper-scythe materialized into her hands, and she transformed her into sniper form. Picking a spot on the ground a distance away, she lined her shot up. She might as well get some shooting practice in; the high-caliber sniper rounds were way more expensive than Yang's. Not something to waste frivolously.

Since she'd diluted the rounds, the kickback wasn't as fierce as the previous, but still shocked her with its strength, making her stumble despite being ready for it.

Rather than Yang being enveloped in pink smoke, though, Ruby was—for the second time.

"Huh?" Yang said. "Guess it's not always the opposite person."

When the smoke cleared, Ruby found herself…

Normal?

"What happened?" Ruby asked. "Nothing changed." She was still in her bikini.

Yang's brow furrowed. "Do you feel different?"

"No?" She tried twisting and looking over her shoulder, but nothing had happened behind her either. She looked and felt the same as before.

"Is it because you already had an outfit active?"

"Maybe? Why wouldn't it do something to you, then? It's obviously kind of smart." Seeing how the side effects only happened at opportune times, not in the middle of deadly encounters.

Yang mulled the event over. "No idea," she finally admitted. "Maybe whatever the effect is just isn't visible. Something might've still happened, even if we can't see it."

"That's kind of scary."

"Do you, you know—? Uh, feel more excited, I guess? That seems like an obvious possibility. 'Cuz your thing is still sticking up."

Ruby looked down at herself. Despite trying her hardest not to think about anything inappropriate, she hadn't softened yet; her cock was sticking firmly up her stomach. Her cheeks darkened rapidly.

"Or that's just you?" Yang asked with a laugh. "Feeling a little frisky? That's fine too. Just wondering. Huh. What else could it be? Something definitely happened—the pink smoke proves that."

"I really don't feel any different," Ruby said.

Yang hesitated, then shrugged. "We'll figure it out eventually. Hell, maybe nothing did happen."

Ruby doubted she was so lucky, but Yang was right that there wasn't much they could do.

"The pressure is gone, at least," Ruby said. "I think we'll be back to regular random chance. Something could still happen, but it won't be guaranteed."

"That's good," Yang said.

Worried over her situation as she might be, she and Yang still had practice to do. So over the next few hours, they wrung themselves dry, experimenting with their semblances and weapons, solidifying the fighting styles they had begun adapting during the Rift. Ruby's bikini lasted longer than Yang's bunnysuit, almost a full hour, though it vanished in a puff of pink smoke without lingering for too long. During its presence, Ruby had struggled to stay focused—especially because of all the glances she caught Yang stealing. Though maybe Ruby was imagining that. Why would Yang be stealing glances?

Yang, for her part, didn't comment on why Ruby kept accidentally springing erections, and she especially didn't comment on how they usually happened when Yang got up-close-and personal during a sparring bout.

The rest of the day was filled with the usual: more practice, errands, administrative stuff for registering for Beacon's entrance exam, and so on.

It wasn't until shortly after she had woken in the middle of the night that Ruby discovered what the second pink dust explosion had done.

Her eyes fluttered open, and her entire body felt flushed, heart beating fast and breath coming deeper than normal. She looked down her body to see her pajama pants sticking up obscenely. Her erection was straining the fabric so solidly upward that Ruby could peek down into the tent it created and see several inches of thick, pale girlcock—the base of it exposed, her pajamas were lifted so high.

Ruby swallowed. This had happened last night, too. At the time, she had firmly decided against entertaining her arousal. A part of her wondered whether if she ignored it, the new addition would go away. Not that she necessarily hated it and wanted it to go away?

Regardless, she had been too intimidated to touch herself, not when the first time had been so—um, explosive. A little shudder went through her, remembering that. She had to be careful. A person could grow addicted to those kinds of sensations.

But clearly just ignoring it was untenable. There was a dark spot where her tip pressed into her pajama pants, precum leaking from her agitated, twitching cock. It needed relief. Badly. One day had been too long to ignore it already…two was starting to drive her crazy. Maybe that was why she'd had so many erections while sparring with Yang.

Ruby bit her lip, heart starting to slam as she made her decision. She slipped her pajama pants down, watching the way twelve inches of girlcock was pulled with the fabric, then bounced free, exposed to the dark night air. Even though it was her cock, she couldn't help but be intimidated…and a bit aroused. Wasn't that way too weird and perverted? Being aroused by her own cock? But again, it hadn't really digested as being hers yet, not fully. And the lewd sight of such an angry-looking, twitching cock was enough to make her heart flutter.

She watched it for a moment, jumping in surprise when a particularly powerful throb had it bouncing.

Slowly, a hand wandered across her stomach before gripping herself at the base. The pressure was immediate and satisfying—a low groan escaped the back of her throat.

It was then, finally, that Ruby discovered the strange effect imposed onto her by the second Pink Dust explosion.

She couldn't move her hand.

Her cock ached, desperate for her to start stroking, but despite her brain telling her hand to move, it wouldn't.

"W-What?" Ruby whispered, so shocked she actually spoke the word aloud.

She withdrew her hand, eyes wide. Her cock throbbed in protest. She tried the other hand, but though she could wrap fingers around the shaft, she couldn't make them move. Or even squeeze hard enough to provide relief.

She…wasn't allowed to masturbate?

Somehow, that acted as a catalyst to Ruby losing control. No—no. She needed relief. Needed it. She'd already put it off for too long. But no matter how badly she wanted it, her hand refused to obey her commands.

She swallowed a gulp of air and, grasping about for a solution, grabbed the pillow to her side and stuffed it onto her crotch, uncaring that she smeared precum across the pillow sheet. Pressing down with the soft object, she thrust forward. The friction sent a shiver up her spine, making her toes curl, but when she went to hump the pillow a second time, the magic took hold and stopped her.

She whined in frustration, trying desperately to keep thrusting, but it simply wouldn't work. Her hips ignored her. She tossed the pillow aside and spun over so she was stomach down, cock pressed into her bed, and tried humping that instead—but, again, it didn't work. The magic prevented her from moving.

Starting to panic, Ruby pushed her cock down so that it was between her thighs, then flexed the muscles there. The pressure she created was briefly electrifying, but once more, she was forced to relax, to remove the pleasure her clenched thighs were providing. And try as she might, she couldn't squeeze a second time.

The only thing she could do, she found, was hump into the bare air without an ounce of friction. Out of pure desperation, she tried that for nearly a minute, bed creaking, her cock bouncing up and down, but it wasn't enough—obviously. It only drove her crazier, the simulation of thrusting into something but getting no actual reward for it.

With no other choice, Ruby forced herself to still, to calm her thoughts, and to silence the whining in the back of her throat. She lay on her bed, panting, frustrated in a way she'd never experienced. She needed relief so, so badly.

She swallowed.

Well.

This was unfortunate. Surely the Pink Dust's effect would go away soon. By tomorrow at the worst. She just had to make it through the night.

She stood.

A cold shower. A very cold shower. That might help.