You place Marceline's soles on your lap (and sneakily put your cock between them). SO Marceline doesn't suspect anything, Black Rose makes her feet oiled up giving you a good alibi. You rub your sister's feet, enjoying how they slip out of your hands. "You know, I'm starting to enjoy women's feet now." Black Rose says in your head. You decide to take things up a notch and start thrusting your hips. You cock slides effortlessly up and down between Marceline's soles. Her oiled toes grab your cock head, and it feels amazing when it slides between them. Marceline is none the wiser, and doesn't suspect you of anything. SO she plays around and moves her feet voluntarily. She believes she's just messing with you, but in actuality, she is giving you one hell of a footjob. You stop rubbing and hold her ankles together while she moves her feet and you thrust back and forth. You pant rapidly and hear black rose moaning in your mind. All the stimulus makes you come with much more force than usual, all over Marceline's feet. She moves her feet away and gives you a thumbs up as thanks. She puts her cum covered feet back in her flip flops and walks away. You enjoy seeing your semen flung onto the floor every time her flip flops slap her soles. Before marceline can get very far, the front door opens. In steps your stepmother, who is quite in shock to see her daughter and granddaughter headless and have cum on their feet. You figure she is about to scream so Black Rose quickly does something to her.