Using Mia's backdoor

Once Tracy has applied a generous amount of lube to her sister's asshole, you give Mia a light smack on the ass indicating for her to get up. She climbs off your cock and kneels down on the floor next to her sister. You stand up from your seated position before instructing them.

"Tracy, get on your back on the couch and Mia get on top of her in the opposite direction."

The two obedient sluts do as you tell them and climb onto the couch, both now face to face with each other's pussy. Tracy's the first to take the hint and grabs her sister's ass, forcing her pussy down onto her face. Mia understands her role too and starts eating Tracy out too. You take a moment to admire your work. A few hours ago they could barely handle seeing each other in some sort of sexual situation and now you had them eating each other's cunts. Happy with what you've achieved, you climb onto the couch behind Mia looking down on her tight little asshole which is winking up at you. In her position, Tracy is also looking up at you as she continues to lick her twin's pussy.

Feeling you're ready, you line your cock up with the entrance to Mia's ass and start to pressure the tip down into her ass. It takes some ****, but you manage to squeeze the tip down into her tight hole but not without some protest from Mia. She lifts her head up from Tracy's pussy and reaches back to try and stop you from penetrating her ass.

"Oh fuuuuck! Please sir, it's too big, you're not gonna fit in my ass."

You give her a hard smack on the ass before saying "get back to eating pussy whore. I'll make sure it fits."

Mia lets out a whimper but lowers her head back down onto Tracy's pussy and puts her hand back down onto the couch for support. You continue forcing your cock down into her ass which is easily tighter than Tracy's was when the two of you first tried anal. This is met with a loud "Mmmmm" from Mia's mouth into Tracy's pussy but to her credit she keeps her head down. She does however raise one of her hands back towards you again out of instinct. You grab her wrist and bend her arm behind her back using it like a handle to help keep a hold of her.

Your cock is now half-way buried in her ass but meeting significant resistance. You decide to start slowly pistoning in and out of her ass, working that first half of your length in and out of her. With each stroke you try and work a little more of your cock into her ass. Mia continues to whimper as she eats Tracy's pussy, as a result of your torment of her ass.

After maybe 10 more mintes of slowly working your way in and out of Mia's ass you finally manage to get your cock the whole way in, unable to push any further into her ass thanks to her big ass cheeks holding you back. You really try and **** your cock in as far as you can, pushing down onto her ass which also forces her pussy down into Tracy's face. Mia lets out some squeals and starts trembling beneath you but continues to take it like a champ. Now that you've managed to bottom out in Mia's ass you start working your way in and out, slowly picking up the pace.

After another 30 minutes or so of Mia enduring this anal torment, you've really picked up the pace and are mercilessly fucking her backdoor. The entire time you've been rearranging Mia's guts, she hasn't stopped squealing into her sister's cunt, but her squeals slowly start turning to moans as she too learns to find pleasure amongst the pain. This is definitely helped by Tracy licking her pussy non-stop, mixing in some pleasure the whole way through. You're making her ass cheeks clap as you pound her ass.

Soon enough you can feel another orgasm coming on.