Step-sister's voyeuristic acts while I'm caged and self-pleasuring at step-brother's place

I was at my step-brother's place, waiting for my step-sister to come over and take me to her house. But as I was killing time, I decided to indulge in some self-pleasure, my fingers exploring every inch of my tight vagina. Little did I know, my step-sister had been watching me all along, her eyes glued to the sight of her step-sister pleasuring herself. As soon as she saw me, she couldn't resist the urge to join in, her mature body taking up the space beside mine. This wasn't the first time we had indulged in some naughty acts behind our mom's back, our secret rendezvous always ending with a steamy session of hardcore sex. This particular encounter, however, was different. It was a voyeuristic experience, my step-sister watching me pleasure myself before joining in, her mature body taking up space beside mine as we indulged in a wild session of amateur homemade sex.