This will make more sense if you read the earlier parts. Don't worry, they're fun, action packed, and build the tension. Read them first! Also, all characters are 18 years or older. Enjoy.
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Sam knocked softly on Bex's door. It was late, but he knew from the light creeping out from under the door that she was up.
"That you Sam?" Bex's muffled voice filtered out into the hall.
"Yeah." Sam bunched his toes in the carpet.
"You ... alone?"
"Yeah," Sam said.
"Come in."
Sam opened the door and slid into the room. He closed and locked the door behind him. His eyes took a second to adjust to the light.
Pussy. His sister's room smelled like pussy. "Are you?" Sam blinked.
"Yeah." Bex sat at her desk. Her pajama bottoms and panties around her ankles. Her right hand furiously moving between her legs. "I couldn't ... get ... the image of you with some girl ... or woman ..." Her eyes were wide and her pupils dilated. A thin sheen of sweat hung to her forehead. "Today ... when I heard you ... humping that chick." Her mouth hung slack as she looked over at Sam.
He wasn't expecting this. "You liked that?"
"Oh God, yeah. The slapping sound ... I could tell ... you were ... really ... uh ... uh ... giving it to her." With that, Bex's eyes rolled back. "Ooohhhhh." She came in her chair, in front of Sam. Her slender shoulders trembled and her blonde hair tumbled back and forth.
"I thought you'd be mad at me." Sam stepped into the room. He waited for Bex to recover.
After a minute, she looked back over at Sam. Her small breasts rising and falling as she struggled to get her breathing under control. "The thought of my little brother dominating some ... girl. Or better yet, some woman. That's so hot." Bex's right hand had slowed between her legs, but it was still rhythmically rubbing her pussy. "Who was she?"
"I ..." Sam squirmed, reached down, and shifted his dick under his waist band. It was so hard it hurt. His balls had already dumped loads on and in his mom earlier that day. And a load in Mrs. Stevens pretty mouth. But his balls felt full and swollen. "I came in to say sorry for bothering you with that girl." Sam looked at Bex's monitor and noticed for the first time what she was watching. A little woman with brown hair was getting ravaged doggystyle by a large man. He held her hair and even though the volume was off, it was obvious she was in ecstasy. "You're watching porn?"
"Yeah, well ..." Bex glanced at the monitor. "It's some married slut getting destroyed. Closest I could get." Bex reached for her mouse with her left hand and paused the video. "You came here to apologize? That's sweet, I guess." She looked back at Sam. "But you need to be more ... um ..." Bex stood up and kicked away her panties and bottoms. "... confident. I'll teach you." She pulled off her top and dropped it on the floor.
"Okay," Sam said.
Ten minutes later, Bex lay on her stomach, face down on her fluffy blanket. "Now, tell me ... uh ... uh ... I'm your slut, Sam."
"You're my ..." Sam plowed into her pussy, smashing her ass cheeks with every stroke. Her poor little pussy was stretched to its max, gripping tightly at his dick. "You're my slut."
"Yes." Bex gripped the blanket with white-knuckled fingers. "You own ... my pussy."
"I own your pussy." Sam slapped at her right butt cheek. It gave a quick little wobble. So different from Joyce's soft ass. "You're my bitch now."
"Uh ... uh ... uh ..." Bex looked over her shoulder back at him, her jaw in a tight grimace. "Whoa, no ... b-word ... dude." The small muscles in her back flexed each time Sam bottomed out.
"Sorry." Sam's face flushed with embracement, but he kept hammering his dick into his sister. He couldn't stop.
"Don't apologize ... dummy." She still looked back at him, her blue eyes twinkled. "You've got me. Now ... take me."
"Tell me ... ah ... ah ... ah." Sam held himself up with his hands just above her waist.
"What?" Bex dropped her face back down to the blanket and closed her eyes.
"Tell me ... you're my bitch." Sam pulled on her hips and moved her onto her hands and knees. She was so light and easy to move around. He pulled her knees together to get her pussy to the right height.
"Oooohhhhhh. I'm your bitch, Sam."
"Bark like a bitch." He pulled her hips back and slammed into her. "Bark for me." Bex was right, this was fun. He'd probably known it all along, which is why he'd started the barking thing with Joyce. Or maybe the rock had known it.
"Yip, yip ... yip, yip," Bex said. She was at his mercy. She'd never been this wet before.
"No ... ah ... ah ... ah ..." Sam sped up his pace. He was going to explode soon. "Like a real ... dog."
"Oh my God. Oooohhhhh. What are you ... doing to me?" Bex shook. She could feel her brother's balls slapping at her clit. "Ruff, ruff ... rufffffff. Oooooohhhhhhh. So, biggggggg." Her pussy spasmed and she came all over that amazing dick.
"Yes. Aaaaahhhhhhhh." Sam couldn't hold back, he emptied inside her, moving her hips in jerking motions to squeeze out all that cum. After he was done, he pulled her off and dropped her on the bed. She rolled onto her side.
"I want to see you do it to someone." Bex still had her eyes closed. Her little nipples were dark on her alabaster skin.
"What?" Sam fell down next to her and lay on his back. His dick stood straight up and pulsed.
"I need to see you dominate a woman, Sam. That would be so hot."
"Maybe." Sam reached over and grabbed her left tit. It was a solid handful. He gently squeezed.
"Please?" Bex rubbed her legs together. Cum leaked out of her pussy.