Yes.

Rachel's idea to reenact our childhood doctor game nearly has my cock bursting as i thrust it in my sister's mouth. And all the while, her fingers are stuffed in her cunt and toying with her clit.

I then pull out of her mouth, and I took out a condom. She whined about losing my 'thermometer', but she saw what i had in mind, and her mood instantly became sexually eager again. "Gotta be sure..." i told her, almost not believing it myself.

"Of course..." she smirked, rubbing her pussy lips to taunt me into filling her up. I slipped the condom on round my length and i walked to her and crawled over her body, lining myself with her pussy. "Let me help you, doctor..." Rachel purred. She gingerly took me in her hand, rubbing the tip of my dick against her labia to tease both of us; she wanted to drive me crazy more than herself. Finally, i took her hand off and plunged into her! She gasped some, tilting her head back as she feels me pulsating weakly in her, and i start going in and out of her. "Be gentle..." she pleaded halfheartedly, looking into my eyes as i do into hers.

"Of course..." I reply to let her know that i was planning on doing almost the opposite. I thrust harder into her, and she grunted quietly each time, enjoying it. I go a little faster and losing that power, but she doesn't seem to be complaining, either way. I then jackhammer so fast into her pussy, letting her gradually loudening moans undulate or shake smoothly some. "You're so bad..." i growl softly, "pretending you're sick for me to fuck you."

"I'm sorry, doctor-- OH!" she tells me, trying to sound innocent. But the sex is distracting her from her performing. Honestly, at that point, i didn't care. I kept pounding her hard and fast and Rachel coiled her arms around my neck and, through the euphoria of our lovemaking, she pulled me in for a deep, passionate kiss. While we kept fucking, i kiss inside her mouth and letting my tongue probe inside and swirl around her tongue.

Rach kept me almost bonded to her, and i couldn't help but... blow my load. My orgasm was blocked but Rachel rocked herself against my manhood, still aiming to cum like i did. I helped out, but more softly than before. But she broke the kiss, and without warning, rolled us over to mount me while i laid on the bed. She bounced on my cock, combing fingers through her hair as her head leaned back some. "Oh my God. Why does feel so good?!" she moaned, putting a hand on my chest while bouncing harder and faster and staying in one place.

She finally howled with pleasure, 5 minutes later, as her climax came. And came she did, all over my cock. Finally, exhausted and sweaty, she fell at my side and curled up, holding me.

"Rachel?" I asked.

"I love you, big brother..." she murmured, drifting off to sleep.