Yes, watched by Steve...

Marissa was lost in a haze of ecstasy. The new found pleasure of eating a girl out, having Steve's cum finally fill her mouth though not in the way she had planned, all shadowed slightly by the fact it had all been with her sister. The shattering of societal norms had brought an excitement she would never have conceived possible. She's always looked up to her sister, wanted to be just like her, now in this sexual conquest she'd surpassed Caitlin and it felt good. She started to think of new things she could do to show how slutty she was, things that would make Steve want her more. As she was debating pinning Caitlin down by her breasts she felt something enter her pussy! She gasped thinking at first it was Steve then she was on her back, staring up at her sister.

Caitlin had gotten bored waiting for something, anything to happen. She could see how Steve was looking at Marissa when the thought struck her, no way would she be shown up by her kid sister. She moved towards Marissa, like a lioness stalking an elk. Marissa too distracted by either fantasizing, or processing what had just happened hadn't even notice Caitlin come right up behind her, that would change. Caitlin licked her middle finger, then in one swift movement inserted it into Marissa. The gasp her sister let out was delicious. Unlike her little sister the idol had a firm grasp on Caitlin, the fact that Marissa was her sister seemed no more wrong then any of the other girls she had fingered in the past. Now she could show off the skills she had developed over the years of sleep overs and one night stands with girls she'd pick up here or there when she was bored of the guy she'd be doing that week. She would show Steve, that she was the bigger slut.

Using her free hand Caitlin swiftly pushed Marissa onto her back, and held her down by one of her firm pert breasts. There wasn't much age difference between her and her sister, but enough that Caitlin was jealous that Marissa was still enjoying a high metabolism that made her not require the gym to keep her thin and beautiful. The surge of jealousy made her ram her finger into her little sister, and Marissa moaned with pleasure. "Sadist" Caitlin muttered as she continued to almost viciously finger her sister, she was three fingers deep and toying with the idea of attempting her full fist when she heard a snicker behind her. She looked at Steve, he was watching them with a smirk on his face and his monstrous cock in his hand, stroking it lazily looking as if he were watching two kids fighting comically over a toy. Not the reaction Caitlin was going for. She wanted him hot for her, she wanted him begging with a throbbing cock that had him in agony for release. She had to step up her game.

Caitlin moved up to Marissa's face and whispered in her ear "If you really want Steve's cock in that whore mouth of yours then follow my lead". Then Caitlin flipped around, positioning her pussy over Marissa's mouth and lowering herself onto Marissa's now sopping wet slit. Sixety-Nine had never failed to get her what she wanted, be it orgasm or just making a guy crazy jealous. Marissa had already started lapping at Caitlin, like a kitten at a saucer of milk, it made Caitlin smirk because she had no intention of being so gentle with her little sister. She started in savagely on Marissa's clit, sucking, swirling her tongue, applying just enough pressure with her teeth, Caitlin was an expert at getting girls off and she was utilizing all her skills.

"Ahh!!" Marissa cried out. She had thought she was doing quite well at eating her sisters pussy, then Caitlin started in on her... it was mind blowing. Caitlin had only started on Marissa's clit and already she was lost in a sea of ecstasy. She could feel her pulse as her pussy lips swelled with excitement, every flick of Caitlin's tongue threatened an orgasm Marissa wasn't ready for, she was enjoying the build up. She was moaning and writhing underneath her sister, her hands with seemingly a mind of their own had been fondeling her breast, pressing down and pinching at her own nipples. A thought suddenly struck her, Caitlin had told her to "follow her lead" She's been so caught up in her own pleasure she'd forgotten that her sisters toned ass was less then an inch from her face. She reached up with her tongue and slid it into her sisters slit, disappointed that Caitlin seemed not to even notice.. clearly Marissa would have to do better. Releasing her breasts she slid her hands up her sisters thighs and with the forefinger of her dominate hand started gentle toying with her sisters orifices. That got a reaction, even though it was slight Marissa felt the pause and subtle exhale from Caitlin. There it was! Marissa slid her finger into Caitlin, and Caitlin bucked slightly as Marrissa started in on her pussy with tongue and finger. It was working but not fast enough, Marissa needed to do more. She brought her other hand in to fondle her sisters anus, and that got a reaction, a notable shiver! Using Cailin's own juices Marissa lubricated her sisters asshole, and slipped a finger in. Caitlin moaned, a glorious moan. The two kept going trying to elicit a better reaction out of one another. While Steve sat and watched....