Slutty step sister invites brother in the tub

I walked in on my stepsister taking a bath at her dad's house. My mom married her dad a few months ago. She is super hot, but a mouthy little slut.I know she pretends she doesn't, but she wants me to fuck her. I just had to figure out how. She got in the bathtub and left the door just slightly open right after our parents left to go out for the night. They said they wanted us to get to know each other, well we did. She acted shy when I walked in. Then asked me to come and rub her back. Her sexy tight body looks just as good as I thought it would. She invited me in the tub and I started rubbing her back, working my way to her firm young tits. I know it's wrong technically. Then she showed me all of her skills Sucking and stroking my cock in the warm water. She loved my cock in her mouth. Then turning around and rubbing my big dick on her bubble butt. Only to turn around again and shove me down her throat like a pro. She's done this before. She finished me off, jerking me directly into her mouth and hand. Such a thirsty girl cleaning my cock with her mouth after I came.