Crystal wants a turn in your ass.

"Now I’ve gotta try that lovely ass of yours,” Crystal announces. She pulls out the chair at Sarah's desk and sits down on it. "Come here, Doug, and get me hard again."

You no longer have any desire to resist your sister's demands. In fact, you are excited about getting fucked again. You kneel in front of her and take her cock into your mouth. If feels very different now that it is flaccid -- so soft and squishy. It doesn't take very long, though, before it starts getting hard again. You take it out of your mouth and start licking up and down the shaft, worshiping your sister's growing member. Your mouth moves further down and you take first one and then the other testicle in your mouth, sucking each one softly. It's surprising how large they still are after emptying so much cum into your mouth moments before.

You move back up to the tip of Crystal’s now fully-erect cock and, in one push, take the entire thing down your throat, eliciting a groan from your sister. You're proud of how good a cock-sucker you've become. It's only your first day and you're already taking large dicks all the way down with ease.

After bobbing up and down your sister's shaft a few times, she's ready for the next step and pulls you to your feet. You know what she wants and step forward, straddling your sitting sister, and start squatting down while she aims her member at your entrance. You feel her head pop inside and moan involuntarily at the incredible sensation of Crystal's cock pushing into your ass as gravity slowly pulls you down. Your sister moans as well as more and more of her member is absorbed into the velvety confines of your ass. You finally come to rest about two-thirds of the way down her cock. It feels wonderful, but you aren't satisfied -- you need the whole thing inside you. Your sister obviously feels the same as she starts to pull you down and grind against you, slowly pushing herself further inside you. Finally, you come to rest on your sister's lap, her cock fully implanted in your colon.

Crystal pulls off her shirt and unfastens her bra, revealing her beautiful breasts to your inspection. You've caught glimpses of them before through her partially open bedroom door as you passed in the hall and the occasional towel slip after she's taken a shower, but never up close and personal. Your eyes go wide as you take them in, so full and perky, the skin smooth and flawless, the nipples erect and pointed toward you.

Your sister smiles at your reaction and asks, "You like what you see?" You've been struck dumb and can only nod your head in affirmation. "Go ahead," she encourages you. You reach out your hand to her breast and gently squeeze. It feels so soft and warm in your hand, filling it nicely with its weight. She pulls your head down to her other breast and you take the nipple in your mouth, eliciting a sigh from her as you gently suck on it. Her hands move to your hips and she starts grinding against you reminding you of the fullness of her cock in your ass. You now alternate between her breasts, sucking and licking one, while you caress the other with your hands. Crystal groans from the dual pleasure in her nipples and cock as you rock back and forth in her lap.

Suddenly, your sister pushes you back up, her nipple slipping out of your mouth. You rise up, so that only her head is still inside you before she lets you go and gravity pulls you back down to the base. She pushes you back up again, a little faster this time, and again lets gravity pull you back down. You start to pick up the pace a little. Gravity is no longer enough -- you start to push down on your downward trips and Crystal thrusts herself up into you. Faster and faster you bounce in your sister's lap impaling yourself repeatedly on her glorious member. "Fuck me, fuck me, fuck me" you encourage you sister over and over again in a lust-filled whisper. The slap-slap-slap sound of your bare butt cheeks against her lap fills the room as she obliges you, your cock flapping uselessly against her stomach.