Emily was moaning as we fucked, but in between the moans she talked about her younger sister, Mary. "She plays with herself all the time now, Daddy. Uhhhh. I swear, every time I go into our bedroom I see the sheets moving where her hand is frigging her little pussy. Ohhh, yes, Daddy, that feels good! She's such a liar, though. She always says she just had an itch. Mmmmm."
"Maybe she's old enough to join our games," I said, still screwing her.
Emily's frowned a little, but she started to fuck me faster. "I thought I was your special slut!"
"You'll always be my special slut," I reassured her, firmly grasping her long auburn hair while I did it. "But don't you want to teach your sister how to make men happy?"
Emily looked even more excited. I watched her pretty breasts bounce up and down as she rode me. "You mean I can teach her, Daddy?"
"Absolutely. In fact," I added, while starting to pull hard on Emily's hair, "Mary can be your special slut toy. You can tell her what do to to please Daddy. And naturally you'll have to make her fuck you too, so she learns how to please other girls."
Emily obviously liked that idea a lot, because she started to scream, "Oh yes, Daddy! Oh fuck, oh fuck, ohfuckohfuckohfuck!" as she came all over my cock.
Emily was panting after her orgasm, so I let her catch her breath for a minute before I whispered in her ear, "I want you to go to the door of the bedroom very quietly, and then open it very quickly. I think there will be a surprise waiting for both of us."