Billy's turn...finally.

Billy gazed at Anna's prone body, face-down and ass-up on his bedroom floor. As his eyes lingered on Anna's butt, he noticed something unexpected: a wet spot between her legs. Apparently, this was turning her on.

A moment ago, he'd thought this was the end of their rivalry for the night. But her half-naked body had him hard as a rock, and knowing she was turned on too made him want to go further. Billy reached down and grasped Anna around the waist, hauling her to her feet and pushed her up against the wall, holding her gently by her throat to keep her from collapsing.

Billy looked at Anna's defenseless, knocked-out face. Her lips were slightly parted and she was still snoring slightly. Finally she was at his mercy. Days of torment at the hands of his female family members--not to mention Karen--and now he had his chance to get payback.

WHAP! Billy slapped Anna lightly across the face. Her face jerked to the side, her hair tossing. She stopped snoring, and stirred slightly.

WHAP! Billy slapped her again and smirked. Anna frowned slightly, not quite conscious but starting to wake up. Billy straightened her face, pushed her up more firmly against the wall, and--

WHAP! A third slap to Anna's reddening cheek and her eyes finally opened. "Whaa...nooooo," she murmured as she came to. Billy felt her legs strengthening, starting to hold her weight. Her hands came up to grasp at his own, the one that pinned her to the wall by her throat. He swung his hand again, not too hard.

SMACK! The blow jerked Anna's head to the side again. "Uuhnn!" she exclaimed. She shook her head groggily, her eyes looking at Billy with a vacant stare. She blinked.

Billy thought she was alert enough to hear some gloating. "You thought you could just do whatever you wanted with me, huh?" he asked. "You actually thought you were stronger than me...hahaha!" Anna's face reddened and she grimaced as she struggled weakly.

Billy glanced down and saw that the wet spot on Anna's panties had gotten bigger. So...the knockout fetish ran in the family. For once, Billy was one mental step ahead of Anna.

"This turns you on, doesn't it?" Billy asked. It was a rhetorical question but he still wanted to hear her answer.

"Whattt?" Anna asked, still slow and confused from the knockout and the cumulative effect of all these slaps.

SMACK! Billy hit her again. This time, Anna's face flushed, her mouth dropped open, and she moaned sexily. "You LOVE this, don't you?" Billy asked smugly.

"Yesss....." Anna breathed, staring at him.

"So you want to be punished for your arrogance in taking me on, right?" Billy asked.

"Yesss...." Anna whispered, looking at him with wide eyes.

Billy smirked again, grabbed Anna around the waist, and spun her around, shoving her face down onto his bed, her ass once again up in the air in front of him. Billy put his left hand on Anna's hip, and swung hard with his right.

SMAAACK! Billy's hand spanked Anna's right cheek with authority. Anna yelped loudly and her body flinched.

SMACK! Another brutal spank, with Anna struggling uselessly against Billy's now-strong grip.

SMACK! A third spank, Anna's perfect ass now starting to turn red.

"Owwwwww..." Anna moaned, almost sobbing. "I thought you meant you were going to fuck me!" she said, the phrase sounding unexpectedly vulgar coming from the nerdy girl.

Billy smiled. "Oh, I am..." he said, "but first, one more--"

SMACK! He spanked her once more, eliciting a tiny scream from Anna. Billy mercifully stopped there, mostly because he didn't want to wake Heather up and have her get involved.

Then Billy hooked his fingertips underneath the waistband of Anna's pink panties, and slowly pulled them over the curve of her hips, past her firm, reddened asscheeks, down over her thighs and off of her ankles, leaving her totally naked from the waist down. He looked up at Anna's exposed pussy, which was pink and shockingly wet. He wasted no time stripping his shorts off, bringing out his massive cock and pressing it up against her. Anna gasped from the heat of his tool against her.

Billy grabbed Anna's hair as he slid his cock inside her. Anna grunted as he slid it in to the hilt, making her whole body jerk. Her pussy felt insanely tight, but it was so wet that he had no trouble thrusting in and out violently.

Billy was banging Anna with no restraint, treating her like an inferior, just like she'd been doing to him. And just like him, some part of her loved it. The main part, it was turning out. Anna's free hand was straying down to play with her clit, Billy couldn't help but notice. He sped up his thrusting and cranked back on Anna's hair. She groaned again, and he could feel her pussy tighten even more as her orgasm began.

"Aahhhhh! AHHHHHH!" she moan-screamed. Her pussy spasmed around Billy's big cock, and he could feel that he was about to cum too. A brief moment of reflection convinced him that nutting inside his own sister with no protection wasn't the smartest idea, so he decided to come down her throat instead.

With one smooth motion, he unsheathed his dick from inside Anna, causing her to collapse on her stomach on the bed, mumbling unintelligibly. Billy grabbed her thighs and twisted, rolling her onto her back. She was lying sideways across the bed, with her head hanging slightly off the opposite side of the bed. Billy quickly walked around and grabbed Anna's head while she was still groggy.

"Finish me off...loser," Billy said, taunting her. He tilted her head back off the edge of the bed, so that she was looking at him upside down. He let his massive cock drop directly on her face, making her shiver. Then he rubbed the tip of it on her lips, and she instinctively opened her mouth.

Billy didn't wait, he shoved his cock into her mouth and down her throat. Anna, realizing this was no ordinary blowjob, tried to retreat from Billy's **** python, but there was nowhere to go. His cock went down her throat, making a visible bulge on the front of her neck as it slid in. Billy was standing, looming over her body. He braced his free hand by pressing down hard on one of Anna's big round tits, making her moan.

Billy started thrusting in and out, one of Anna's small hands pushing at the front of his leg in a futile effort to slow him down. He put a hand on Anna's neck so that he could feel his own cock through it. With each thrust, his balls were slapping Anna's face, adding an extra layer of humiliation to the act. He pulled the hem of her tank top up from her waist to her neck, baring her perfect breasts, grabbing and pinching one pink nipple.

It only took a few seconds of this position to bring Billy to the edge of a tremendous orgasm. The feeling of fucking Anna's face was exquisite, and her nude, writhing body stretching out in front of him was quite a sight. Not to mention the humiliating nature of the position.

Billy thrust his cock deep down Anna's throat and held it there, grabbing under her shoulders and pulling to make sure he was as deep as he could be. He saw Anna's naked chest expand as she braced herself. Billy started shooting pump after pump of hot cum down Anna's throat. One, two, three, four thrusts and she was done, pushing desperately at his thighs, unable to keep up. Billy held her in place until he could see cum leaking out at the edges of where her lips met his dick. Then he slid his cock out of her mouth, jacking it hard. Five, six, seven, eight pumps went on her lips, her neck, her tits, her belly, leaving most of her body glimmering with it.

Anna coughed and sputtered, sitting up on the bed and pulling her tank top over her head, so that it didn't get cum on it. Billy's cum was dribbling down the corner of her mouth and chin, and flowing freely from her nose. She still looked half knocked out.

Billy studied her closely. He wanted to know if he'd had the same kind of psychological effect on her that she'd previously had on him. Had he reversed their roles?

"Can I use your shower?" she asked.

Billy was perplexed--of all the things she could have said, that was pretty low on the list.

"Wouldn't want to run into Mom looking like this," Anna explained.

Billy quickly nodded, and Anna stood. He stole a glance at her bare ass as she disappeared into his bathroom, and a few seconds later he heard the shower turn on.