Who'd turn down a free orgasm?

"Yeah, what the hell," Nat says with a grin. "Thanks!"

"No worries, sis," Alex says. He watches her unabashedly, stroking his cock with one hand and working his finger into Kylie's ass with the other, as she steps into his room and strips off her boxers and panties in one smooth motion. Nat crawls onto the far end of the bed and spreads her legs wide, lightly stroking her labia as she bites her lip and looks down at the girl on the bed in front of her.

"Stop looking at me, perv," she orders her brother, who chuckles.

"Fair enough. C'mon, Suckslut, get in there." Kylie, whose eyes are slightly rolled back in her head, moans and, gasping, crawls forward. She gently begins to lick and kiss Nat's lower lips, and Nat tosses her head back with a satisfied sigh. She tangles her fingers in Kylie's hair and the blonde girl, encouraged, begins to lick her more vigorously.

"Good girl, Suckslut. Really put some effort in..." Alex is working a second finger into the girl's ass, and she moans, which sends a vibration of pleasure through Nat's body. Nat gasps as the other girl finds her clit and gives it a gentle suck.

"Mmph, she's really good, Alex!" Nat exclaims, staring down at Kylie through half-lidded eyes.

"Yeah, she'd better be. 'Cause I've had an idea to make this a bit more interesting..." Alex leans forward, working the girl's asshole with his fingers. "So, Suckslut. Your goal here now - unless you'd rather fail it deliberately - is to make my sister cum. You make her cum on your slutty little mouth before I cum in your fuckable ass...or I'll tie you to the bed and take a break to play Fortnite until I'm ready to fuck you again. And only then will I get back to God of War. Got it?"

Kylie makes a muffled noise, but Alex isn't really waiting for a response. Pulling his fingers out of her, he lines his dick up with her asshole and slowly but firmly presses his way into her back passage. Kylie lets out a muffled scream as he fills her completely, gripping Nat's thighs as she quivers and tenses. Nat gasps at the sensation, wrapping her hands around the other girl's head to keep her in place.

"How come you always go for their ass?" she asks her brother, gasping, as he starts to slowly pump in and out of Kylie's hole and the blonde girl, overcoming the initial sensation, moans and begins to slurp at her pussy again.

"What can I say? I'm a romantic," Alex says. He's gripping Kylie's waist with both hands, beginning to thrust harder and harder as her anus adjusts to his girth. "I feel like I should save the pussy for girls I actually, y'know, care about, not just bus stop whores like this."

"Mmmmm fuck you. You're the worst, dude," Nat tells him, gasping slightly as Kylie's tongue circles her clit, then dives in deeper.

"Says the slut currently pressing the whore's head into her cunt," Alex retorts. "What are you, trying to do some kind of reverse-birthing thing? She's - ha! - not going - hngh! - anywhere." He's got a steady rhythm going now, and is starting to pant. "She still doing good?"

"Fuck yeah she's good," Nat gasps, slightly breathless as she feels her orgasm building, the swirling heat and pulses of pleasure rippling through her body. "She might - mmm! - even win your little bet..."

"Not if I have anything to say about it!" Alex lets out a growl as he begins to ream the girl's ass harder and deeper. Kylie starts to let out little shrieks with each thrust, attempting but largely failing to keep up her task of eating out Nat. Nat holds her in place nonetheless - the rhythmic shoving of Kylie's face into her crotch is something of a turn-on in itself. Kylie keeps trying to lap at Nat's lower lips, but at this point is mostly just hanging onto the other girl's hips.

"Fuck her, Alex," Nat gasps, watching as her brother ravages the girl's asshole. "Give it to her good!" She can feel that she's close, and starts playing with her own clit as well.

"Fuck yeah!" Alex groans, closing his eyes in bliss. "Fucking...fuck...gonna fucking...fill your...ass! Hnnnngh!" With a roar, he buries himself to the hilt in Kylie's anus, roughly pulling the girl's head up by her hair as he does so. Nat moans as she strokes her clit faster and faster, getting off to the other girl's thoroughly used expression as Kylie's eyes roll back into her head.

"Fuck that's hot. Eat me, Suckslut!!" As Alex lets go of her head, Kylie falls forward and Nat seizes her by the sides of her head, pulling her forward and grinding onto her mouth. She cums with a sudden, sweeping fury, waves of pleasure roiling through her body as she mashes her pussy into Kylie's face and the other girl feebly licks and slurps at her. Nat watches through half-lidded eyes as Alex finishes his own orgasm, pulling out of Kylie's ass and roughly stroking himself, spraying ropes of white jism across the blonde's rear and back. Some of it gets as far as Kylie's hair and one rope even lands on Nat's leg, making her laugh breathily through the aftershocks of her orgasm.

"Haha, ewww," she says. "Come on, slut, clean it up." She pulls the other girl's face, shiny with a mixture of sweat, a few tears, and Nat's juices, over to her thigh, and the girl obediently licks up Alex's cum, swallowing it dutifully. "You're a good little slut, I'm glad Alex brought you home. Thanks for sharing, bro." She smiles up at Alex, not at all discomfited by the sight of his deflating but still hard cock. Her brain feels ever so slightly foggy, though not as much as when she's the one taking a dick...still, it was fun.

"No problem, Nat," Alex says with a grin. "Seems like I'm probably gonna have her around for a couple days, so feel free to stop by again if you want to use her. Suckslut doesn't mind, do you slut?" he gives Kylie's ass a solid smack as he rolls off the bed.

"Mmmph!" the blonde girl moans, clearly cock-drunk. "N-no, sir...anything..."

"Good."

Nat crawls off the bed and retrieves her panties and boxers, slipping them on as Alex grabs some rope from his box in the corner. "Say hi to Anna for me, yeah?" he asks, and Nat nods as she heads for the door. As she's leaving, she sees Alex roughly roll Kylie over and pull her feet toward her head, starting to tie one ankle to the headboard of his bed. "Now, I warned you what would happen, Suckslut...I'm gonna have to play a nice long game now, and you're gonna have to lie here with a nice big plug up your ass to keep you ready for the next time I want you. Ready for your punishment?" Nat grins as the door swings shut, cutting off Kylie's needy whine of assent. Lucky girl... she thinks, before shaking her head and coming back to herself.