Take advantage of my sexy new Step-sister

Seeing her eyeing my cock and seeing that gorgeous body, I can't help it. With my finger already on my temple it comes out before I even realize what I'm saying. "Well hop on in and you can get a closer, look." with that I remove my other hand from my cock and let it stand at attention.

Before I realize it she dives in headed straight for me, I am sure she is looking at my hard cock as she swims right up to me. As she starts to come to the surface I feel her tits against my cock, as a matter of fact looking down I see she specifically puts her tits on either side of my cock and slides up my body. As her head breaks the surface I feel her hand wrap around my cock.

"Much more than I had thought." she winks and squeezes my cock.

Still with my fingers to my temple, still slightly in a state of shock being caught like this, my mind is reeling as to what to do now with my new 'step-sister' with her hand wrapped around my rock hard cock. I think to myself 'what the hell is she going to do next?'

"What do you want me to do with this next?" Squeezing my cock and starting to stroke it under the water. "I'll do anything my big," squeezing my cock "brother wants me to, really, anything"

[good time for you guys to toss ideas my way, literally anything you want even if it's just a few words to get the ball rolling, I'll expand on it]