Nobody

Cassidy and I both stop and look behind her where the noise came from. We don't see anything or anyone.

Cassidy whispers in my ear. "It could be someone watching." She then puts my still hard cock in her mouth and sucks the cum off of it. She puts my cock back in her pussy and starts to gyrate her hips on my cock. "Keep fucking me, this is sooo hot."

I just stare out where the noise came from.

Cassidy whispers again. "If it is someone and they had a problem with it, they would have said something or broken us up by now." She slaps my ass and pulls me in to bottom out in her pussy.

I start fucking her again but not quite with the same vigor as before

"I know how to get you going again." Cassidy winks at me and whisper yells. "Fuck your big sister, fuck me as hard as you can...brother."

I subconsciously get back to the pace and roughness that we were at before the interruption. I grab her throat with my left hand, lightly **** her in the process. "You've been teasing me for years now with what you wear around the house, all your hot friends and yourself hanging around the pool during the summer. And worst of all leaving your used thongs and g-strings in the bathroom after you shower.

I realize I may have gotten a little specific, especially if there is someone watching us. But in for a penny, in for a pound. I give Cassidy 5 full thrusts and I pull my cock out of her and put it in her face. "Suck it you filty slut, taste your own pussy off your brother's cock." I demand.

Cassidy seems to really like how this is going, takes my cock in her mouth and starts giving me the blowjob of a life time, it's super sloppy and drool is dribbling down her face and onto her neck and shoulders.

After a few minutes on that I pull my dick out of her mouth. "On your hands and knees, slut." I demand.

Cassidy with a huge grin on her face, gets into the doggy position. "Fuck me as hard and as deep with your giant cock, brother!"

I slap Cassidy on her ass, hard enough to leave a clear handprint. "My slutty older sister will not tell me what to do." I ram my cock into her dripping pussy. "You've been wanting this for years, haven't you?" I wait for her reply, which she gives none. I slap her ass again. "A whore will answer when spoken too."

She grunts. "Yes, I've been wanting this forever now." She starts rolling her hips while pushing back against me. "I used to leave my dirty panties around to drive you crazy. I loved picturing you jerking off into my thongs."

I grab a handful of her hair and pull on it. "So has my dirty, horny sister always been this slutty? Cause if that's the case I should punish you." I gather all the saliva that I can and spit it on her asshole. "You know what's about the happen."

She screams in ecstacy. "Oh fuck! Do it! Fuck my slutty ass...brother"

I pull my cock out of Cassidy's pussy and press the tip against her asshole. It slowly slides in but there is a ton of resistance. I stop pushing and spit on it more.

It was then when I noticed a shadow over the two of us. I looked up to see who it was...