Upstairs.

When you get to Sarah's room Tiffany is lying blindfolded on her bed, giggling as your sister prods unpredictably at different parts of her body.

Smart, you think as you step inside. We don't know how she'd react if she found out I only own part of Sarah's body.

While you're still thinking Sarah looks up and sees you at her door. "Oh, Ryan's here! That means we can get started."

She helps Tiffany up to stand facing you and begins to unbutton her blouse. She runs her hands over the freckled cashier's body and stares at you provocatively over Tiffany's shoulder while she slowly strips her.

Tiffany gets more nervous with each lost article of clothing. "Does he like what he's seeing?" she asks when Sarah holds her thong in the air like a trophy.

Sarah flicks the thong at you and squeezes Tiffany's breasts. "He's head over heels. Your turn to undress me now."

"What? Ok, I'll try." Tiffany says and turns to face Sarah. Reaching out clumsily, she feels along Sarah's front until she finds the buttons of her shirt, the top half of an old school uniform that stops just under her belly button. Both girls laugh as Tiffany struggles with the buttons, but to you it's a pretty sexy show as Tiffany's body shakes with nervous laughter and she caresses your sister a bit on her way from one button to the next, imitating the way Sarah had felt her up earlier.

Once she's free of the shirt Sarah has to help out by unclasping her bra, but her skirt and panties are easy enough for Tiffany to pull down her legs. Soon enough both stand fully nude in front of you, except for a belly button ring in Tiffany's case and the artwork on Sarah's lower abdomen.

"So how are we doing this?" Sarah asks you.

"Use your mouth to make sure she's wet enough for me first, then I'll let her go down on you while I fuck her."

Tiffany accepts your proposal silently, your sister seems game too. "As long as I don't have to do it the way Mrs O'Brien did in that video."

"Nah, you pick the position."

"Awesome! Tiff, will you sit on my face?"

"Um, ok. I'll need some help getting into position though, unless you want me to take this blindfold off?" Tiffany asks hopefully.

"Keep it on, I'll help you." Sarah leads Tiffany back to the bed, where she lies down and pulls the naked cashier up until she's straddling Sarah's chest. From there she uses her hands on Tiffany's thighs to guide her forward until she's on her knees, crotch hovering over Sarah's face.

Tiffany carefully lowers herself to sit down, her hands on the headboard to steady herself as your sister starts licking. You hurry around the bed to get a frontal view of the busty cashier, who doesn't take long before she starts breathing heavily. "You're into this huh? Are you this worked up from watching porn on the way over?"

"No, that didn't do much for me," she breathes. "But your sister is pretty cute and... uuugh! And she knows what she's doing down there."

You reach out to grope her heaving jugs. They're big and soft and covered with almost as many freckles as her face. "Are you going to cum already?"

"I'm sorry sir. I know I'm supposed to be here to serve you, but if she keeps going I won't be able to help myself."

"Go ahead, nothing wrong with enjoying your work," you reassure her as you reach down to tug on her belly button ring gently.

"You mean it? Thank youuuu-" She tries to continue, but your sister's tongue has started flicking over her clit frantically. Tiffany groans loudly and stops trying to speak as she grinds her pussy into Sarah's face. You continue playing with her piercing, but lift one hand back to her breasts to squish them and tweak her nipples. A few minutes later she regains her voice only to loudly announce "I'm coming!"

Her grip on the headboard tightens, and she squeezes her thighs as your sister carries her through her orgasm with long licks up and down her slit.

When Tiffany releases the headboard you help her off Sarah's face and let her sit on the bed while she catches her breath.

"Sounds like I did something right," Sarah says happily, to which Tiffany nods. "Are you ready to return the favor?"

"I am. Your brother wanted to fuck me while I do, so I guess you just stay where you are and I'll get between your legs?"

After Sarah nods and you confirm verbally that that works for you, Tiffany crawls to the foot of the bed and gets on all fours facing your sister. Sarah spreads her legs and puts a hand on Tiffany's head to show her the way to her pussy while you strip next to the bed.

By the time you're kneeling behind her, Tiffany is eating out your sister with the same enthusiasm Sarah exhibited when she went down on Tiffany. She doesn't even react when she feels your hands on her, so you edge forward until the head of your cock touches her pussy. She still doesn't pause her work, but she pushes her butt back a little to swallow the first inch of your meat.

It feels amazing, hot and wet from her recent orgasm. You can't help bucking your hips to give her another inch, and she moans into Sarah's cunt.

Having Sarah eat her out loosened Tiffany up enough that you don't have to take it slow. Her pussy squeezes around your shaft, but doesn't offer any resistance as you push forward until you bottom out inside her.

"Oh wow!" Sarah exclaims when you start thrusting. "I didn't think cunnilingus could be improved by having a guy around, but I love how you're mashing her nose against my clit every time you push her against me."

Instead of reponding you pull back and give Tiffany a forceful thrust, driving her face deeper between Sarah's legs. Both girls moan loudly. Then you reach under her to rub her clit while you rapidly piston your dick in and out of her. Sarah has to hold her head steady to keep her mouth on target, but Tiffany never falters in her duties. Her tongue moves up and down Sarah's slit nearly as fast as your cock moves inside her, and Sarah's moans get louder and more enthusiastic.

Sarah is the first to cum, but the sounds she produces are so erotic that you quickly follow suit, and you double the efforts of your hand against Tiffany's clit so she orgasms as well before you pull out. But Sarah's hands remain cramped in Tiffany's hair and the sounds she's making continue.

You wonder what's going on until you realize Tiffany hasn't stopped eating her out. "Tiff, you've done your job," you tell her. "You did good."

A few seconds later Sarah's hands relax and Tiffany sits up. Still blindfolded, she turns to you. "I'm glad I could be of service. Thank you for shopping at Agent Provocateur!"