She does; like a good little whore

You decide to give her the time she needs, and after another few minutes, with Carrie's help, something clicks in Cassidy's head.

Her throat relaxes and you are able to pull her head all the way down until her cute nose presses against your pubic bone, buried in your short curlies.

Carrie is impressed; even she often struggles to take the whole thing. "Holy shit, Cass! You did it! That's amazing. Such a natural little whore. Mom would be proud."

Cassidy can't respond or even breathe until you let her back up and she gulps down air like a drowning person. She seems pleased, but you keep a stern expression. "Well done. Now finish the job. Carrie, keep her hands out of the way."

Carrie grabs both of her sister's hands and holds them behind her back while Cassidy works very hard to suck you off, deepthroating you with surprising skill in an extremely erotic hands-free performance. The sight of both girls, dressed in nothing but their underwear, working together to fulfill your sick fantasies... it's too much.

You grunt as the orgasm explodes, forcing wave after wave of hot cum into Cassidy's open throat.

She makes a mewling sound around your cock and tries to pull away but your iron grip on her head keeps her firmly in place.

"Swallow it. Swallow it or **** on it."

She swallows. The sensation of her throat muscles straining and flexing around your cock is heavenly, even as you gradually do let her up to breathe and swallow properly. Finally, you are satisfied, and she is released to pant and cough up various sticky fluids.

She's a little shaken. You're a little worried that she's overwhelmed and having second thoughts about staying at your place. She just needs a little encouragement. After all; she just made a non-refundable down payment. You're sure you can make her stay. "That was really great, Cass. Honestly, you did well. The first time is a little rough, but you got it. It'll be easier from now on. You'll see."

She nods and even smiles a little, wiping her chin with her hand. "Yeah. Thanks." She stares at the lipstick smeared all over the base of your cock as if unable to believe she ever got that whole thing in her throat.

Carrie strokes her hair. "Who knew you had it in you, sis! That was incredible. You are so hot! I can't wait to do this again. Maybe next time you can be the one helping me!"

Cassidy's smile grows a little more genuine. "Yeah, that was pretty cool. I kind of enjoyed that, actually. Okay, this could be fun." She looks from her sister to you and back. "I had no idea you guys were so insanely sexual. This place is crazy." She pokes her sister in the boob with a finger. "And you really could have warned me about the no-clothes thing."

Carrie laughs. "I didn't want to scare you away."

You interrupt the sisterly bonding by cupping Cassidy's chin and drawing her focus to you. "Yes, we like to have fun. But I want you to make no mistake, here, Cass. You are my whore. You buy your food and housing with your body. Accept this and we'll have fewer problems. And I want you to show some gratitude for the opportunity."

She gulps, shrinking a little under your gaze. "Yes, I understand... thank you."

"And?" You prompt, very curious to see where her mind goes with the total lack of direction.

"And..." she says, eyes scanning quickly as she tries to think of what you might be looking for from her."...and I look forward to being your whore."

You smile. "Good girl. Carrie, take her to the spare room."

This is going even better than you'd hoped.

As the girls stand and prepare to leave, you remember that the spare room doesn't even have a door on it: you took it down months ago and now it's in a storage room in the basement. You hadn't planned that but you're definitely going to enforce it. Whores don't get privacy; it's best she learns that lesson quickly.