SIBLINGS EXPERIMENT

I walked into my bedroom and found my sister sprawled out on my bed. Nova was lying on her stomach, legs idly kicking back and forth in the air, her phone and notebook in front of her.

"Hey bro," she greeted me.

"Hey yourself," I said, shrugging out of my hoodie.

Nova had gotten into the bad habit of wearing some very, very tight shorts lately. The way she lay in my bed showed off her cute butt way too nicely, though she kindly didn't turn to look at me and gave me the chance to stare a moment before sitting on the bed next to her.

"You know you have a room of your own, yeah?" I said.

Nova shrugged. "What fun's that?"

"I mean..."

"Besides, I wanted to ask you some things."

I rolled my eyes. "Of course you do. You've been asking such weird questions lately."

"Have not," Nova pouted, acting offended. "I'm doing research. Learning. Bettering myself. These are noble endeavours."

"Last week you asked me whether you should start wearing a padded bra," I said.

"To make my tits look bigger," Nova said, as though it was perfectly reasonable.

"The week before, about what kind of shorts to wear to make your butt look good," I continued.

Nova wiggled her booty. "How are these ones doing?"

"I mean... fantastic, and I think you know that," I said.

She grinned, fully pleased with herself. "Good. I thought so."

"Why are you asking me these things though?" I asked. "It's weird."

"It's not," Nova said. "You're a boy, Sol."

"Thanks for noticing."

"And you've got relevant opinions," she said. "Plus I know when you stare at my ass, you really mean it."

"... is there a way to stare at an ass and not mean it?" I asked.

"Well, you know," she said airily. "It means more coming from you."

"You shouldn't want your brother staring at your ass," I said. "Or helping you pick out bras to make your tits look bigger."

Nova chewed the end of her pen, somehow making it look cute and naughty while she pondered. "Do you like staring at my ass?" she finally asked.

"In those shorts? Yeah."

"So we're both winning then."

"One could so argue," I agreed evasively.

Nova took the time to jot down a note in her book. Something about me, no doubt. She was doing that a lot lately. It probably made me look like a perv, all full of remarks about how I liked her butt and which bras looked best on her. Not my fault. She asked.

"You don't show this stuff to anyone, do you?" I asked. "Whatever you're writing in there?"

"It's research for making myself attractive," Nova said. "I've told you that. I don't show anyone, but I do talk about it with my friends."

"Oh god."

"What? It's useful. They benefit too. You want me to hoard knowledge?"

"How much new and fresh knowledge are you really gaining here?" I asked.

"Plenty," Nova assured me. "Like the right amount of midriff to show off to get you to peek without making Mom and Dad mad. That's useful. And that these shorts work. I was worried too tight was going to be slutty or not really look good actually. But it seems to be working out."

I blushed as I realized she'd caught me staring again. I hadn't even meant to. It just happened, the way her butt cheeks were perfectly shown off in near-skintight shorts, and the way her kicking legs kept drawing my eye. That was probably part of her experimentation too, though she hadn't mentioned it specifically.

"The shorts might be pushing it if you're trying not to get a talking to about your outfits," I said, attempting to deflect from my indiscretion.

"I think so too," Nova said, wrinkling her brow in thought. "But I've been trying out cunningly not letting the wrong people see them from behind. They're modest enough from the front." She perked up. "Plus now that Mom and Dad have taken off traveling for the summer, it's kind of the best time to try some more risque stuff out."

"You're crazy," I said.

"I'm scientifically minded," she countered.

"The Venn diagram overlaps on occasion," I said.

"Hehe, good one," she said without a hint of taking it personally. "Ooh, by the way, check these out."

I looked warily at her phone as she scrolled through a few pictures for me.

"Are these... are these just all pictures of your friends' butts?" I asked.

"In tight shorts, yeah," Nova said. "Whose is the cutest, you think? I know who I'd pick, but I want an unbiased opinion."

"This is weird, Nov," I said. "But you really want to know?"

"Of course. That's why I asked."

"Your butt is the cutest," I said.

"That's cheating!" Nova protested. "I asked about the pics."

I ignored her. I could see how obviously pleased she was with my answer. The way she beamed, the happy blush on her cheeks. The way she immediately flipped to a different page in her notebook and gleefully wrote down something she wasn't about to share with me.

Unless it was my imagination, Nova even arched her back a little more, gracing me with an ever so slightly better view of her booty while she scribbled hasty notes to herself. She was killing me, but in such a fun and thoughtful way.

"You know the danger here is I'm going to start checking out your butt more often," I said. "You're training me to misbehave."

Again I was dead positive that Nova was thrilled to hear that.

"Not my fault," she said. "But if you could possibly keep track of how often you feel that way, what I'm wearing and doing at the time, how long your gaze lingers, what--"

"I'm not doing that," I said.

Nova expressed mild frustration with that response. "Kind of a waste if we're not collecting data, don't you think?"

I tilted my head and stared thoughtfully at my sister's cute little booty. "I don't think it's a waste."

She wiggled her hips in response. "You're enjoying looking?"

"Yeah."

Nova nodded like I'd just given her an opinion on something totally innocuous. "I can work with that, I think. I can still take notes, I'd just need to know when you're looking or interested. Some way of recording what's happening."

Her gaze fell to my crotch, which all of a sudden made me embarrassed. Yes, I was getting kind of hard. Not like fully erect over my little sister or anything, but certainly having a reaction to her perfect booty.

"Don't make a note of that please," I sighed.

Nova grinned and scribbled something down anyway.

"You're going to make this weird," I said.

"You got hard," she chirped. "Not me."

"Only a little," I protested weakly.

She tapped her pen on her chin. "Can I see?"

"No."

"Please?"

"Absolutely not."

Nova turned her big, pleading eyes on me. "Even just through your underwear? It's just hard to see what's going on while you're wearing pants."

"I think that's by design," I said.

"You're making this difficult," she grumbled.

"I'm really not," I said.

Nova retreated into her thoughts, with the occasional moment of jotting something else down in her notes. I was honestly curious just what exactly she was keeping track of in there, and how much help it was actually going to be to her. To me it only made sense that something looked good or it didn't. Trying to quantify arbitrary things felt like it would be very difficult or impossible.

I played on my phone, relaxing into just sharing a room with my sister while she did her own thing. It was nice just to hang out sometimes. I could almost forget what she--

"What if I touch it?" Nova asked.

And there it was again. "No," I said.

"Without looking I mean," she clarified, as though it made all the difference.

"Still no," I said.

"Over the pants?"

"Sure."

"Really?!"

"No."

"Mean!" Nova said.

I could see her pouty face from the corner of my eye, but stayed focused on my phone.

She tried a few more angles, and it actually got pretty amusing what she'd suggest, and how increasingly exasperated she got with my refusals. There was, too, something flattering about my dick being so desired, even given the current context.

I had to admit, she got me good in the end. She shifted around in my bed quite oddly, almost like she was throwing a quiet and delicate tantrum. It wasn't that, but I had no idea what she was actually doing until she took my hand and placed it on her butt. The way she'd maneuvered her body suddenly made sense, but very little else did.

I froze, hand firmly on my little sister's ass. Her tiny, skintight shorts weren't hiding much from my touch. I could feel her pretty well, and... it was nice. Really, really nice.

"Feel free to provide any thoughts or feelings you're experiencing right now," Nova said, almost casually, but with a faint hitch in her voice that I almost missed.

"There's something not normal about you," I said.

"I mean in regard to your hand on my butt," she clarified.

"My statement is quite related to that, actually."

But I wasn't pulling away. I didn't want to. I hadn't ever wanted to fight too hard about her wanting me to check out her butt, for instance. I was even less inclined to argue about feeling it up.

She was going to let me do it, too. I could shift my hand and fingers, squeeze her ass, explore the fascinating curves, and Nova would absolutely just lie there and take notes on the experience.

At first I told myself I was just going play chicken with her. See how long and how far she'd actually let me go before she realized this was crazy. But I knew right from the start that was a lie. I knew my sister way too well for that. Not that she'd ever encouraged me to feel her up before. But if she wanted it now, it wasn't likely at all that she'd change her mind.

"You've got a great butt," I finally told Nova.

I could practically see the beaming grin on her face even with her looking mostly away from me.

"Noted," she said, happily marking that down. "Anything more specific?"

"Not that I'd care to try and elaborate on," I said.

"Sometimes I worry you don't have the true soul of a scientist," Nova said.

"I'm excellent at physics and engineering, thank you very much," I said. "Your niche applications of biology and psychology are not my strength."

Nova snickered. "Fair. Ok, let me gather some more data then."

I knew she was going to try something outrageous. Once again, I knew my sister pretty well. She had a face like she knew she was about to get away with something that she knew she shouldn't.

She went for my pants. I wasn't as surprised as I probably should have been. More fucked up was I didn't feel like stopping her. If she'd asked I'd have told her no again. Since she didn't...

I didn't know what to make of the implications there. I shouldn't be more open to things she didn't ask for. Yet much like placing my hand on her ass, just doing the thing was getting easier acceptance from me.

"Ooh, very hard," Nova cooed excitedly. "Lift your butt for a sec, let me pull your pants out of the way."

"Terrible idea," I said, even as I complied.

I knew she was going to pull my cock out of my boxers too. I still could have stopped her. I didn't.

"Oh that's nice," Nova breathed as she got my full erection out. "Fully hard, yeah?"

I nodded. "Yeah," I said, sounding a bit strangled even to myself.

Her fingers felt so good on me. Her touch was not something I should have felt. Not like that. But she had me right where she wanted me, interested and compliant. I knew I was weak like that when I got horny, I just hadn't realized that it would even work for my baby sis.

"See this is what I'm talking about," she said, running her fingertips up and down my shaft. "This is valuable information. If I can do this to you, I'm onto something.

"If you can touch me inappropriately?"

"No, silly. If I can make you hard like this. And..." Nova's eyes widened and she rubbed her thumb over the head of my cock. "And if I can make you drip like that," she finished huskily.

"Yeah, I mean precum's gonna happen if you play with me like that," I said, failing to sound as casual as I would have liked.

Nova bit her lip and kept rubbing me, delighting in each fresh bead of precum she milked from me.

"Useful information," she muttered. She seemed to be trying to convince herself as much as me.

Nova dragged her notebook over to where she could jot notes with her right hand while her left settled into a slow stroking motion intermixed with teasing the tip of my cock and greedily swiping up precum.

It was a bizarre and confusing experience for me, but one that felt incredible.

"You know you're jerking your brother off," I said in a low voice.

Nova started and glanced at me as though she'd half-forgotten I was there. She slowly grinned. "Not yet I'm not." She hesitated. "I haven't really done that though. Is it ok to practice?"

"You're... you're seriously asking that while you've already got your hand wrapped around me?" I asked.

She cocked her head, and the impish sparkle I saw in my sister's eye was not at all one of scientific detachment. "Would you like me to jerk you off?"

"Nov..."

"Sol."

I wasn't going to win a battle of wills here. It wasn't fair at all when she was still running her hand slowly up and down my cock. I still waited and let the tension build, just to salvage some kind of pride.

"Please," I finally said. "Please jerk me off."

It might as well have been my sister's birthday for how gleeful she looked. It wasn't about the handjob itself, I was well aware of that. Probably some combination of the power she had over me right now, and the information she'd gleaned about how I operated.

"That's something to explore again," Nova mused, writing her notes before focusing on my cock again.

"What's that?" I asked, hardly daring to voice the question.

"How horny you have to be to ask me something like that," she said. "From your sister of all people."

My cock twitched and spurted extra precum in her hand. She gasped and giggled and wrote it all down of course.

"Oh my god," Nova squealed. "Really?"

"Shut up! It's not a fair test," I insisted.

"Uh huh," she said, stroking me with more purpose. She gazed at me intently, waiting patiently, her eyes piercing through me. "But this is rather fascinating all the same, don't you think? And it calls my data into question if you're going to respond so positively to your sis-ter playing with you like this."

My cock twitched again in her warm little hand. I couldn't do anything about it. I had no control. She was going to think I was some kind of total perv at this rate.

"I don't think about you that way," I mumbled, face flushing embarrassingly warm. "This is not normal."

"I could almost believe that," Nova said thoughtfully. "But I also believe now that more testing is in fact required here. Because you do react to the incestuous component, even if as you claim that's not usual. Kind of a bad bro-ther, aren't you?"

I moaned helplessly as Nova kept up her sensual torment. I wished it wasn't so hot when she reiterated our sibling status, but it actually fucking was. Her stupid games, her stupid tests, they were doing things to me. Of course they were. I'd have a reaction to any girl in bed making me check her out, grab her ass, and lie back while she played with my cock.

But yes, there was some specific thing about her being my sister. I'd only be lying to myself to keep pretending otherwise. I just didn't like it. It was embarrassing.

It wouldn't have even been so bad maybe if she'd been a hot older sister. Even a sexy mom. Those could have been excusable. Getting this way for a cute and mischievous little sis reflected poorly on me, I felt.

But I couldn't stop her stroking me. I didn't want it to end. She felt so good. So good. My baby sis's handjob...

"I don't want to spoil the result," Nova said softly, "but then again I didn't think to time it properly anyway this time. I think you should cum for me, Sol. Do you want to cum?"

I whimpered. "Yesss."

"Good. Then cum for me, ok?" Nova was feeling the horniness of it all too. I knew she was. But she was still very much in charge. She smiled wickedly at me. "Cum for your sis-ter?"

I did, I came for her. Exploded and made a mess all over myself and her hand. She kept stroking me, giggling madly at the hot cum getting on her, but not letting it stop her. I had to eventually nudge her hand away when my orgasm was well and truly done with.

Nova stared at the cum on her fingers, and only slowly and absently fumbled for her notebook. I had no idea what she still felt she needed to record from this event, but she was dedicated, I had to give her that.

"That was... useful," Nova said, hesitating like she'd temporarily forgotten how to speak.

"It felt really nice," I said.

"Yeah?"

"Yeah."

"You think other boys would like it too?" Nova asked.

"Is that a serious question?" I asked.

"Yes, of course."

I laughed and shook my head. "I can't with you right now. But like, maybe if you jerk a boy off, don't follow up with asking about what other boys might enjoy."

Nova nodded seriously and started writing again.

"Don't write that down," I sighed. "Oh nevermind. You're not going to listen, are you?"

"I serve a higher calling," she informed me.

"I don't know that handjobs are a higher calling," I said. "Although I suppose that's a religion I could get behind."

"Not that kind of higher calling, silly," Nova said. "Now if you'll excuse me."

I watched my sister patter out, somehow still glued to her cute, tight little booty even after cumming.

"I wasn't keeping you here," I muttered after her. Though in fact some twinging part of me wanted her to stay. I was not about to admit to such things right now. She'd only write it down, probably.

****

Nova didn't do anything weird for the rest of the week. Instead of relief, or indeed indifference, I found myself fantasizing about her butt and thinking about the feel of her soft hands on me while I was jerking off. That wasn't good. She'd be so smug if she knew.

It was probably for the best if that event had been a one-time, crazy thing anyway. It wasn't like incestuous handjobs were encouraged in society. Even if they did feel really good.

I didn't think anything of Nova inviting Skye, one of her best friends, over. That was a perfectly normal thing. I liked Skye well enough, as far as my sister's friends went. She was relatively fun and polite.

She also had a cute butt, as I slowly realized. I may not have really looked before, and perhaps it was due to Nova putting my mind onto this sort of thing. After checking out my sister's butt, checking out her friend was a step more behaved if anything.

It took embarrassingly long for it to dawn on me that this was a deliberate thing. Skye was wearing small, tight shorts, very similar to the ones Nova wore so often these days. Very unlike her usual. And the way she kept blushing and smiling around me kind of confirmed that something was up.

It was all so obvious once it clicked. This was Nova experimenting on me again. She didn't actively write in her notebook where I could see, but I was sure she was doing so. I wondered belatedly if Skye had been in those butt photos my sister had tried to get me rate previously. Most likely she would have been.

I took an opportunity when Nova wasn't in earshot to question Skye about the situation.

"You know what Nova's up to, yeah?" I said.

Skye flushed and wouldn't quite meet my eye. "What do you mean?"

"With the shorts and all. In front of me."

Skye squirmed. "She said you'd like it," she finally said, blushing even more furiously red than before.

"She's not wrong," I said. "You've got a cute butt."

I thought Skye might just melt away right there. More than just her butt was cute, as it turned out. The freedom to notice these things was kind of fun.

"Really?" she squeaked.

TBC.........