Liz’s glass was topped up more regulally, and comments towards her became a little more suggestive. They saw Liz as an easier target now, so now Liz...was alone, and the guys were going to try as best they could to get her knickers down. Simon was getting very touchy feely with Liz and Liz was not turning the attention away. Although she was a stunning young lady, she was still flattered that this successful guy was making a play for her.Simon was ready to play his ace card. He invited Liz. Her pussy was as juicy as Susan had ever seen it get. He must be doing something different to her. She watched as her sister's legs shook and quivered from her orgasms. She started looking closer. He was doing her the same as he always did. WHY the big difference in the way she was reacting? Then she saw what was different. His thumb wasn't holding her pussy. It was inside her ass. He was fingering her ass while he was fucking her.He started to roll her over to mount her from the top, and she. Finally as you both stop cumming. I pull out of your pussy, and lay down beside your sister. You rise up off your sister collapsing beside me. You reach over and put your hand around my hard cock. Saying, “It’s time for you to put this in my sister. It's time for you to fuck her." I look into your pretty blue eyes and say simply, "OK." Your sister is still lying on her back. I get up and kneel down between her legs. She is watching me. Not saying a word. I reach down under her knees and lift. If he can smoothly convince them there's nothing to it, fine. But it's more likely he's going to show some sort of guilty surprise. If that happens, coach him on how to fall back to a more acceptable (and more likely) cover story: No, he's not having sex with you, never did, never will, what a crazy idea! But he's a little embarrassed, a little guilty, because (like every other teenage boy in the Known Universe) he'd thought about it. He can even "confess" that, years ago, he even tried to.