The sisters, both in their late teens, had always been close, but the arrival of their new stepbrother had ignited an unexpected spark. As they lay entwined, their bodies slick with sweat, Amelia and Grace took turns riding Robert's throbbing cock, their hips moving in perfect sync. The room was filled with the sounds of their pleasure, the creaking of the bed, and the wet slapping of flesh against flesh. Robert, his hands gripping their hips, couldn't believe the intensity of the experience, the sheer taboo of it all driving him to the brink of ecstasy.