My fingers slipped and slithered around my slit, playing over my inner and outer lips, grazing up towards the sensitive skin at the top of my thighs and stroking downwards towards my arse. I slid a finger between the clenched cheeks of my bum and delighted in the burst of sensations which ran through me as I pressed it into my flesh. Mary was dry-lipped, an expression of fierce concentration on her face.

I raised my legs from where they were rested on the settee opposite and pulled my knees up towards my chest, my ankles flopping down towards my bum cheeks. The movement rolled me further on to my back, and my arse became exposed, the cheeks parting and revealing my hole to the watching Mary. This was the most vulnerable, humiliating pose imaginable, all my private places on full display to this middle aged woman seated opposite me. I pulled my legs higher, parting them wider, exposing myself even more fully, and I knew that my arsehole would now be gaping in front of her.

I rolled my index finger around my pussy, coating it in my fluids, covering it with the sticky mass. I fixed Mary with my gaze and she stared, awed, back at me. Deliberately and slowly, I moved my look from her to my finger, and I knew that she would follow my line. Equally slowly, I took my finger from my pussy and repositioned it at my rear end.

"Do you want me to do this?" I asked. I wanted her to be involved, I wanted her to tell me what to do.

"Yes," she replied.

"What shall I do?"

"Put your finger in..."

"..my arse?" I completed.

"Yes."

I pressed against my arsehole, feeling the pressure, feeling my body forcing against the intruder. I relaxed my muscles and pushed. The tip of my finger penetrated, and I felt it locked into place by my sphincter muscles. I pushed again, and again, harder and harder, and eased my finger in to the first knuckle. All the while I continued to diddle my clitoris with my other hand, stroking my middle finger gently round and around it, grazing the nail against the base, drawing sensuous patterns on my fevered skin. Another push and my finger slid in as far as the second knuckle. I began to move it around in my arse, feeling the sensations of my finger probing and exploring in my passage. I pressed harder, forcing my finger in as deep as it could go.

Ensuring that Mary had a good view, I began to thrust the finger in and out of my hole. At first it was painful, but the lubrication quickly eased a steady passage and I built up a pleasant, thrusting rhythm. After a minute or so it slid easily in and out and I began to press with my middle finger as well. It took a bit longer to slide the tips of my two fingers into place, but once I did the lubrication I had built up allowed the fingers to slip further in fairly easily, and after another minute I had both fingers penetrating deep into my arse. I pushed them as far as they would go and left them there, moving them inside me, to and fro, in a gentle, sideways motion. The sensations as they grazed against the walls of my passage were delightful, little shivers of excitement flitting through my bowels and into my pussy.

"Is this the kind of dirty thing you imagined, Mary?"

"Oh yes."

"Even dirtier, maybe?"

"Yes, it is," she admitted. I thought so. I wouldn't have believed in a thousand years that Mary would have envisaged something like this. "Is it worth it? Are you enjoying the view?"

"Yes," she replied huskily.

I was getting seriously turned on by the situation I had created for myself. Mary had wanted me to expose myself, had wanted to see Harriet the Slave Girl in action again, but I was determined that I wouldn't offer her a basic show: on the contrary, I wanted to show her the extent of my depravity. She couldn't understand how I could do such things, such "dirty" things; well, I resolved to show her what "dirty" was, and what things I was capable of. It simply wouldn't have done for Mary not to be shocked by what happened, and I felt, with my fingers encased in my arse, that I had done a good job in shocking her.

I began to fuck my arse with my fingers again, delighting in the full, heavy sensations two fingers brought to my bowels. Two fingers are much more powerful than one, create a far greater sense of fulfilment. I could feel my body tense, the muscles in my legs and arms clenching and straining, and the wonted waves of sensation began to mass in my pussy and arse. My clitoris was aching, far too sensitive by now to touch, and my fingers stroked round and around, not daring to go near it. My hand pistoned at my backside, thrusting the fingers in and out, in and out, and I found it difficult to keep my eyes open. I wanted to close them and lie back and let the moment flood over me, but I was determined that I would keep eye contact with Mary at all times. I may have been in a humiliating position, but I was not ashamed: what I do, I do because my Master wills it, and I will not hide from the consequences.

The moment arrived, the climax erupted, and the sensations pulsed through me, convulsions and spasms racking my body. My sphincter muscles locked on my fingers and I was unable to thrust them in and out; instead I rolled them round and round, probing and pressing inside me as the darts of pained pleasure flickered and fluttered through me. I was bobbing up and down on the seat, unable to sit still, and I let out a cry of excitement. A flush swooped over my body, leaving me hot and sweating, and still the moment rolled on and on. As the excitement subsided, my sphincter muscles relaxed and I was able to move my fingers again, thrusting them in and out a few last times, adding a few more tantalising moments of ecstacy. My eyes were locked on Mary, and hers were locked on my fingers. Finally, I ground to a halt and lay on the chair, quite still, fingers still embedded in my arse.

"Now then," I said. "These fantasies of yours. Do they go beyond watching me have a wank?"