Help Peter

You walk over to Peter, watching him fuck his sister from behind, his back muscles contracting. You walk up behind him and watches over his shoulders as he fucks Emily, his hard dick going in and out, making her moan. You realy enjoy this sight and rub yourself while stroking Peters chest and stomach from behind. But you want your fun with Emily to. So you need Peter to finish up so you can get some action. A perverted idea comes to your mind.

You start touching his back, kinda massaging it while he keeps pounding his slutty sister. Your hands go further and further down until you are squeezing his buttcheecks. You spread them and he slows down. "Crap" , you might ruined the moment, but then you hear he moan and you know that you can continue.

You smile as you gently places a finger on his asshole, gently putting som presure on it. "Yes keep going" he pleads, picking up the pace.

You spit on your finger and lubricate Perts asshole. Gently, ever so gently you push your finger up in his ass, your heart racing, feeling incredible dirty, but even hornier. Peter moans as you get two knuckles deep inside of him. He keps pounding, moaning as you finger his asshole, talking dirty in his ear.

"Yeah fuck your sister you perverted fuck. Do you like hearing her moan because of your dick. Go on, cum on her."

Peter didn't need more encouragement, and with a moan he pulled out and came all over Emilys back. Rope after rope of thick cum.