Rubbing herself

Katie's eyes are glued to the image of her sister bouncing on you. She's slouched down in her chair, legs spread, the top button of her jeans undone and her right hand pushed deep down into them. You can see her hips grinding up and down up and down, into whatever her hand is doing to herself, and you can take a pretty good guess what her hand is doing to herself.

It all feels dreamlike. It can't not. Not only are you currently buried deep inside Greenie, your girlfriend, her sister, seems to be enjoying every second of this.

Or course it was all planned out in advance. But still, after six years with Katie, you could have never guessed that she'd be this excited by something like this. It's almost alarming. If you don't know this about her, what else don't you know about her?

But you can't quite bring yourself to worry about... well, anything right now. So you focus on what's in front of you. Which happens to be Tess's nude, sweaty body.

You lean in toward it, cupping your lips around her left nipple. It's so much surprisingly bigger than Katie's, and you have to work to swirl your tongue around the entire thing.

Tess responds with a light moan. She's lighter than her sister, but her body bounces on you differently than Katie's, more furiously, more impulsively.

She whispers at you, when you pull your mouth off her breast. "Enjoying yourself?" There's something sensual yet comically obvious about the question. The constant reminder that what's happening is both awkward and awesome.

"Yes." you whisper, looking up at her face, seeing it glow in a way you've never seen before. "And so is your sister I think."

Greenie responds with a laugh, a half-giggle, half-chuckle. "Is she diddling herself?" Tess asks. You've never heard Tess use a euphemism for masturbation before, but it's not surprising that that's the one she'd choose. "She said she probably wouldn't be able to resist."

You glance over at your girlfriend once more, not that you need to confirm what you've already seen. But, yes, she's still rubbing herself intensely, her eyes now closed, her jaw dropped, her breathing tense.

"Yes" you respond to Greenie. "I'd say so."

Greenie shakes her head. Her long brown hair, as it falls down at you, sways around your face. "She doesn't even have a good view of what we're doing." It's probably an offhand comment, but it hangs in the air, and you don't know if you should say the response that's on the tip of your tongue.

Fuck it, you think. Everything is crazy now. You're currently penetrating your girlfriend's little sister. What on earth would make you think the situation calls for timidity. So you say it. "Want to give her a better view?"

You can't help but think maybe, just maybe, the suggestion might turn Tess off. After all, as naught as all this is, it's still her sister.

Instead Tess responds. "What do you have in mind?"