Marisa and her big dildo.

My redheaded stepsister’s room was dim, but the orange light from the street lamp outside her window was enough. Marisa was crouched on the bed, her hair hanging over her face and looking like it was damp with sweat. The muscles in her calves and thighs were tensed and flexing as she bounced up and down, sometimes slowly and sometimes with greater speed and energy. It took me a few seconds to spot the large dildo she was clutching in both hands and impaling herself upon, but even in the meager light from the window I caught the glistening juices that covered it.

Marisa’s enormous breasts jiggled and swayed with her body’s movements, and I stared in shock at the size of her erect nipples, about an inch long. She kept reaching up to cup one of her bouncing globes, massaging it, tweaking a nipple or squeezing her mountainous titflesh before returning her attention to fucking herself silly with her big fake cock.

I was so astounded at this vision of rampant female sexuality that I almost didn’t notice that she was mumbling to herself in between her moans and grunts. I strained to listen to the whispered words, no less intense for being spoken quietly. “Don’t tell me to slow down, cunt-licker! You’re gonna take it! I’m riding you, I’m riding your cock. You’re gonna take it any way I want you to take it!”

I was fascinated and so turned on by this new side of Marisa, but I knew I shouldn’t get caught watching. This wasn’t a girl who’d accept me as a replacement for her fantasy man, she’d just be furious with me for spying on her. As I tiptoed back to my own bed, I wondered whose cock Marisa was riding in her fantasy of erotic dominance. I’d never thought of myself as sexually submissive, but I masturbated frantically that night with images of sucking Traci’s snatch intertwined with a fantasy of Marisa’s huge tits bouncing in my face as she rode me to a screaming orgasm.