The experiment begins

Anna’s experiment started the very moment Billy woke up from their last match. Groggy and drooling, still all gloved up like he was ready for a fight, the athletic, muscular champion lifted his head from the carpet with a dull moan.

His bleary eyes opened, to find himself still in Anna’s room. As they adjusted to the light, he saw that Anna was standing above him wearing a lab coat and goggles, with a smirk on her face.

“Look who finally decided to come to…~”

Her words filled his groggy brain, bouncing around the empty space as it slowly reformatted itself. Whatever she’d done to knock him out, it had got him good. The champ let out another meek groan.

Bored of waiting for her sloppy older brother to fire back with one of his dumbass comebacks, Anna spoke again. There was a teasing lilt in her voice, as if she knew something he didn’t.

“Hey, Billy.”

“What the f… Anna?”

All at once, Anna suddenly lifted her top, showing off her bra-covered tits - then knocked him out again before he even had time to take it in.

WHAM!

His head fell back to the floor, bouncing slightly off the soft carpet. Back asleep. Back knocked out. Totally taken down by his nerdy little sister.

“Mmmm…” Anna smirked, slowly lowering her top. She tsked at him, then clicked her pen and began writing down the time and details of this first KO on her clipboard, smiling.

See, the stimulus she had decided upon was her own body. She wanted to see if she could make her oaf of an older brother associate seeing her in her bra and panties, with being knocked out. If she could use that sight to return him to this dumb, woozy state whenever she pleased…~~

Billy would wake up some time later, dazed again. “You’re free to go,” Anna would say, gesturing to the door in a way that made the ends of her labcoat swoosh. She knew that this experiment would take more than one night. Still not all there, Billy followed her command without a second thought, stumbling up to his feet and then shuffling off to his own bedroom to sleep.

And so the experiment continued. Many more knockouts, over many more days. Of course, between them, the siblings were still going to school - still going about their ordinary days. But each day, as promised, Billy would challenge Anna to a boxing match - which he would lose. He always, always lost. Then, the moment he woke up… Anna would flash her breasts, and send him back down again, noting the details of this second defeat diligently.

Anna was thrilled to find that Billy seemed to have no memory of her experiments - at least not yet. Whether he was too embarrassed to admit it, or whether she just put him out too fast after showing him her breasts, she didn’t know. But she loved seeing him slowly lumber back to his bedroom each night, thinking that he’d just lost another fight to her, and seemingly having no idea of the second battle she was having with his subconscious brain.

Anna sighed, pleased, as she finished up the latest notes of her study. She loved using her clever mind to break him down, piece by piece. Whittling away at what he once was while she used him like a lab rat.

While it was difficult to measure his progress when he’d been going down in one hood punch the whole time, she couldn’t help but notice that he seemed slower and weaker in each of their pre-emptive matches. And every time he woke up, Anna would provide the stimulation, then WHAM! Down he goes.

It never got old. Anna couldn’t hold in her gleeful giggle, as Billy gawked her tits and got oneshot again. Defeated by the superior warrior.

She felt like an early human, taking down a wooly mammoth with advanced tools and a superior mind. As strong as he was, as good a fighter, and this awkward little nerd was destroying him.

The feminist in her loved reducing her irritating champion of a big bro to this. Seeing his sluggish movements. Hearing his pathetic groans.

“Guhhh…”

Billy was on his knees, looking up at his topless sister. Recently, she had begun wearing nothing but a bra and panties under her open labcoat, forgoing the formality of lifting her top.

And now here he was. Teetering. Unsteady. Eyes locked onto her chest. Onto those surprising curves…

Anna retracted a little bit at her brother’s gaze on her breasts, feeling shy. She still wasn’t used to being looked at that way. But she pushed away the feeling and quickly knocked him out again.

“G-Go back to sleep!” she commanded.

BAM

“Uhhhhh…” Billy moaned, his head bobbing down as the shot sent him out again.

Not wanting to corrupt her results, a few days in, Anna told Billy that he was free from the boxing matches. This would ensure that all of his knockouts came after seeing her bra-covered tits, to not pollute his subconscious.

“You’re just too easy, bro,” Anna bragged, after freeing him from his obligation to challenge her each day. “I’ve figured you out. You haven’t even put up a fight all week!”

“Fuck off, Anna,” Billy responded, fishing around the inside of the fridge. He was almost back to normal, during the parts of the day where he wasn’t just coming to from a harsh K.O. “I don’t fight a lot of scrawny nerds, you’re just too small of a target.”

Anna grinned. It wasn’t a particularly strong retort that he’d given her, but it was honestly the best he could do after losing by knockout so many times. What else could he even say? Besides, Anna knew she was going to make him pay for it later.

So Anna began sneaking up on him. Skipping the boxing matches, she would get his attention somewhere around the house - Billy would turn his head, get a flash of Anna topless, and WHAM! Down he went, with his little sister writing notes about the exact way he fell, and the details of whatever stupid knocked-out face he was making.

The experiment continued. To make it more entertaining for herself, Anna started getting creative with the KOs. The simple punches were fun, but it was even more satisfying to knock Billy out with a kick - though it required her to sit atop the kitchen counter, legs dangling, to get enough height before calling for him to turn around and see her in a bra. Then BAM! Foot to the face, and lights out!

Anna was growing more confident, too. If knocking him out in boxing had helped her, then repeatedly sleeping him as he gawked her breasts had completely elevated her. Having a big, strong man stare lecherously at her bra, then putting him out, was working wonders for the repressed little nerd.

At one point, she even got daring enough to try knocking him out by jumping and bumping her breasts into his chin - but he wasn’t quite far gone enough for that to work, and she had to quickly put him down with a punch before the embarrassment of his confused stare made her shrivel up.

Still, even if trying to knock him out with her boobs hadn’t worked, he was certainly getting weaker at the sight of her breasts. Towards the end, he was so out of it that she could even surprise him in his bed and **** him out with her hand. **** him! This charismatic, popular, athletic boxing champion, too dazed to fend off his nerdy little sister and her one hand!

“Ghk… Ghnnngh… Ahggg…”

Anna squeezed the hand on his neck, overjoyed.

“Come on, bro… Fight me off. Stop me. You look like you’re about to get choked out by a “scrawny nerd”…”

It wasn’t strictly professional, but Anna loved it. Watching him slowly fade beneath her, his eyes coming to a close with a final stuttering moan, then beginning to drool, was the best… She made sure to bring her face as close to his as possible for that one, to REALLY watch him go out. Really rub her face against his as she watched his eyes gloss over. She didn’t even mind that she was topless. The power of it all more than made up for any embarrassment the shy girl would normally be feeling.

God, that was just electric in her pussy… Bye bye, bro. Back to sleep…

But this couldn’t continue like this forever. Very soon after starting the experiment, Anna ran into an unavoidable roadblock she had to overcome. Something that, if not addressed, could completely halt the entire experiment.