Laurie lifted herself up, and Carla rose up, her face covered with a sheen of Laurie's girl cum. She saw Zack's cock, back up to a full, and cooed, "Now, I want that next load, bet those balls are all swollen with a big load, and my mouth is going to suck it all out of you!"
Laurie cooed, "Ok Carla, on your knees, I think the best way to suck cock is the classic subservient cocksucker position, with your tight lips all ready to ride that pole. Oh yes, such nice, plush cocksucker lips, all wet and slippery with my juices, they will be perfect for our cum slut needs."
Laurie turned to Zack and said, "This will be Carla's first time sucking a cock. We've been practicing by using our dildo, so be nice to her, don't try to force it down her throat. Let her take you at her own pace."
Zack was more than ready, the sight of his sister, a cum hungry subservient cocksucker, made his lust roar. From her what he guessed was a 34D chest, down to the sexy curve of her waist, and the bare bald pussy lips, knowing that his own blood sister was going to give him her cock sucking virginity had him stiff as a steel bar.
As Zack presented his cock, Laurie moved in behind Carla, molding her body against Carla's back, kissing up and down her neck, then looking over Carla's shoulder, she cooed, "Look sweetie, your first cock suck, that's 7 inches of sucking pleasure. Go for it my sweet sister just like we practiced."
Zack was almost breathless as his cock head was an inch from her lips when Carla's tongue came out and licked gently at the cock head. Zack's grunt of pleasure urged her on, and Laurie cooed, "Next step baby."
He watched, open-mouthed as Carla's lips slid around his cock head, closing her lips just behind the head. Laurie cooed, "Now, swirl that tongue, get that cock head all wet and slick."
Zack let out a long moan of pleasure, god that felt amazing. The wet swirl of her tongue around his cock head was unlike any feeling he'd ever enjoyed, the most he'd gotten were a few hurried handjobs from his neighbor as an 18-year-old birthday present. Sure, he'd gotten his nuts off, but it was so fast and over so quickly. With him having just blown a huge load into Laurie's cunt, he'd need to recharge, and he could enjoy the build-up.
Laurie was cupping Carla's boobs, gently pleasuring her stiff nipples, and she cooed, "Now, slide your mouth down slowly baby."
Carla was eager to do so. She started to inch her mouth down, god, sucking off her brother, plus Laurie working over her tits so pleasurably really had her warmed up and she enjoyed her brother's sounds of pleasure. Having his most personal organ in her mouth, and being the one to deliver that pleasure, was wildly exciting.
She managed 5 inches before she had to pull back, and Laurie cooed, "Now, start a rhythm sweetie, ride that stiff pole."
After the first few moments of getting the hang of it, Carla's mouth started to glide smoothly up and down as her mouth rode his pole. Carla found it to be a wildly erotic experience. Her sister Laurie was pressing against her, gently rubbing her stiff nipples up and down her back while her boobs were pleasured by Laurie's soft, loving hands.
Seeing the look of lust beginning to overcome Zack's face, and the sensation of soft silky skin over his hard prick going in and out of her mouth had become more and more arousing. She was hungry to get the first hot load to paint her tonsils.
Zack was savoring it just as much. Her sister's full, lush lips were made for cocksucking, the sight of her luscious red lips ovaled around his dick, feeling her tongue swiping at his prick and the way her cheeks would hollow as she sucked at him, god, the sight was fucking amazing. His moans filled the room as her wetly sucking lips gave him the cocksuck of a lifetime.
Laurie could feel the prickles of excitement as she watched her brother and sister give in to their desires. Now that she was their sister, well, step-sister, but Carla had made it very clear that as far as she was concerned, Laurie was as much a sister as if they had been born and lived together, which made her warm. Having the love of a sister really made her life complete. She loved Carla as much as Carla loved her, and they had discovered, together, how far that love could take them...
*****
The first few days of living together had been somewhat stilted and getting used to. Carla had been surprised when Laurie asked if she could sleep with Carla in the same bed, not wanting to make her feel like she was an outsider, or being excluded from the family unit, she agreed. The downside was that Laurie could not get herself off in the privacy of her bed. But, she could rub herself off in the bathroom, and she assumed that Carla was also using the bathroom to masturbate, assuming she did.
One night, they were lying together, talking about their lives, when Carla said, "Listen."
After a few moments, they heard some giggles, sighs, soft moans, then a rising tide of squeaks, more grunts, and groans joining in, coming from the master bedroom.
"Mom and Dad are fucking right now. They wait until it's this late, figuring we're asleep, so they can fuck without disturbing us."
Laurie was thinking, damn, we're hearing people fucking. She could feel her pussy warming up quickly, even though it was their parents, she couldn't deny how hot it was making her. If she was alone, she'd be stroking her tight little pussy while listening to the lust-driven soundtrack.
Laurie just couldn't take it anymore, her panties were soaking, and her pussy practically begging for relief. The darkness emboldened her, and she had slipped her hand under the covers, into her panties, and she started to rub, her fingers just inside her wet seam, making a faint squishing sound.
Carla was silent, then her voice had a husky undertone, hearing what she was up to when she asked, "Laurie, are you...?' "
Laurie's voice had been a lust-driven coo, "Yes, oh fuck yes I am...I'm so horny, I need it...go ahead Carla...stroke your sexy pussy...masturbate with me...you know you want to."
A few moments later, Laurie could hear Carla's gasp of pleasure, and the gentle squishy sound matching hers, as Carla gave in to the lust driven heat.