That evening.

Despite Heather's joke that you have already eaten you are famished by the time dinner comes around and eat a very generous serving of your Moms cooking. You help your Mom with the dishes and are surprised when your sister comes and helps with the drying up too. Her status as Daddy’s little girl had gotten her out of her fair share of chores growing up. As helpful as she is, she does spend more time trying to whip you with the tea towel than actually drying

Still, Heather's good mood continues for the rest of the evening with the two of you sitting down in the lounge room to watch the new TV show The O.C. together. A chick’s TV show about a rich family taking in a troubled teen. Heather particularly liking the male lead Ryan. She would like the bad boy, of course, remembering she had sex with Kyle just this afternoon. After the show, you complete what homework you have on the computer in your bedroom.

With it getting late you decide to turn in for the night. You leave the computer on as you head to the bathroom that you share with your sister. The light and fan are already running but you don’t hear the shower going so judge it safe to go inside. Heather dressed in a pair of flannel pyjama bottoms and a singlet top is in front of the sink brushing her teeth and spits out a big mouthful of toothpaste as you walk in.

“Oh, you know how to spit something at least,” you say joking.

Heather pulls a face at you and bends down to wash her mouth out as you go to step past to get your toothbrush. Heather poke her ass out so that she is blocking your path. You grab her hips and try to push her out the way but she grabs at your side with her free hand and pulls you back against her.

If she is going to be playful, you’ll be playful too. Grabbing her hips, you press your crotch into her ass and give her a quick hump. Heather lets out a moan as you do, arching her back even more and spreading her hips a little wider. Having Heather rubbing her arse against you in this position causes your cock to fill with blood in only a matter of moments so you are soon grinding your very hard erection against your sister’s pussy.

You begin to pant as you are practically dry fucking your sister from behind. You slide your hands under her singlet and up along her stomach and ribs until you feel her firm breasts in your hands. Perfect handfuls of teenage flesh. You can see your fingers squeezing her nipples in the mirror in front of you. A look of ecstasy on her Heathers face.

You briefly think about cumming in your pants when Heather suddenly stands back up straight, turns around and gives you a hug.

“I’m locking my door tonight, so don’t bother trying to come in,” she tells you before kissing you for a long moment and leaving the room.

You are left with your erection and to brush your teeth alone.

Returning to your room past Heather’s closed door, you go to shut off your computer when you see a message from Katherine has popped up on MSN Messenger while you’ve been gone.