A story about a young and devious lesbian mistress and her older slaves

Late at night, startled by some strange noises coming from the kitchen, I get up to investigate, only to find our visitor there enjoying my favourite, biggest toy. Not the least bit embarrassed by my presence, she soon includes me in her game, with my butt a willing and sore recipient. But when she proceeds to slowly turn me into her lesbian slut, I become more and more uneasy. Was this, what I really was? Just a slave to be used for her relief and pleasure?