The irony of it all was that I was not present when the decision that changed my life was made.

It was Saturday on a warm spring day and I was in my bedroom dressed in a tee shirt and shorts while, down stairs, my mum, older sister Sue and her friend Phoebe were sitting in the kitchen. They were discussing the town's forthcoming fancy dress parade. Mum had suggested that they enter as Cinderella and her Ugly sisters, with me being Cinderella.

Mum had pointed out that it was the sister's characters that were ugly and with me as Cinderella the judges would certainly gives us a prize for originality if nothing else.

"Do you think Paul will go for it?" Sue had asked.

"I wouldn't be surprised," mum had replied.

So, after they had planned what to do, Sue and Phoebe had come up stairs and called me into Sue's bedroom. There they put the proposed idea to me and I of course had refused it, although I had to admit to myself that I was intrigued. They tried cajoling me, during which Sue said that mum had commented that she thought that I would like to play the part and would enjoy wearing knickers. I was surprised at this comment and protested no. 

At this point they clearly decided to put their plan in action and at a pre arranged signal they suddenly pounced and before I knew what was happening I was on my back on Sue's bed with Phoebe astride my chest with my arms and hands pinned down by her. At the same time Sue started to pull down my shorts. I struggled and in the process slid down the bed until my face was under Phoebe's dress and against her satin panty clad crotch. Slipping down the bed had made it easier for Sue to remove my shorts and then my briefs.

With my face between Phoebe's thighs and pressed against her panties my struggles had stopped, instead I began to nuzzle her crotch. I felt Phoebe shiver and at the same time I became aware of Sue pulling some silk knickers up my legs. Both these sensations caused my penis to grow. Up to this moment I think my sister still thought of me as her little brother but the feeling of the silk knickers caressing my cock had made me hard and at that moment Sue realised that I was a bigger brother than she remembered.

"Oh, Phoebe, look at this," she said.

As Phoebe turned to look her grip was relaxed and my arm was freed so I slid my hand to the top of her thigh and slipped it into her panties. At the same time as I felt her pussy I felt a hand clasp my erection through the silky material of the knickers. My thumb found Phoebe's clit and teased it even as I was being played with. 

It didn't last long. I felt Phoebe's legs tense then her panties were soaked by her climax and moments later I came in the knickers that had been pulled up my legs. 

Almost immediately after this happened Phoebe climbed off me and said she needed to get home. Now I could see my sister Sue. She had her eyes closed and one busy hand down the front of her shorts.

I picked up my shorts and popped back to my room still wearing the sheer knickers. Once there I caught a glimpse of myself in a long mirror and turned for a better look.

With my tee shirt rucked up, my cock tucked between my legs and my long hair I looked almost female. The image turned me on so much that I was stiff again in no time. The feel of the silky knickers against my visibly upright cock helped as well. The result was that I had to have a wank.

Nothing was said by anyone for the rest of the day but I slowly realised I liked the idea of being Cinderella, assuming I was dressed properly.

Next morning, just before I entered the kitchen I heard mum and Sue talking. Sue was telling mum that Phoebe didn't want to go through with the fancy dress.

"What should I do?" she asked.

"You could go as Prince Charming and Paul could still be Cinderella," replied mum.

At that point I entered the kitchen and after the usual good mornings said I was prepared to go along with the Cinderella thing.

"Cool," said Sue, "we'll start after breakfast."

So an hour later we were in Sue's bedroom and she was telling me to get undressed. When I got down to my briefs and I hesitated she insisted on every thing. At the same time she was sorting through the bottom drawer of her chest of drawers.

To my surprise I saw it was full of all varieties of feminine under wear. I was surprised for Sue had always dressed in a very tom-boyish way so I did not know she had all these girly things hidden away.

"Are those all yours?"

"Oh no. Has Mum never told you that dad liked to dress up."

"Did he?"

"So mum says, its part of the reason he left us, apparently."

This revelation gave me cause for thought but at that moment Sue has all sorts of lingerie spread out on her bed for me to put on.

First, sheer white stockings with a satin garter belt and she showed me how to clip on the tabs so the stockings were nice and tight. Then some white satin panties that got me thinking of Phoebe and yesterday, with a consequent stirring that Sue ignored. A matching bra that had to have the cups filled with silk handkerchiefs. Finally a full silk slip to cover every thing. As she smoothed it down and her hands pressed the soft material against my skin I started to get an obvious erection made more noticeable by the large bulge in the front of my slip.

At that moment I was standing in front of a long mirror with Sue behind me. She could clearly see the state I was in and she slid one hand round my waist and grasped my stiffness through my undies even as she whispered in my ear, "We can't have this, can we. The judges won't believe you are Cinderella with this pointing at them"

Even as she said this she began to stroke my cock and for me the feeling was wonderful. I could see she too was turned on for her nipples were stiff buds pressed against her tight tee shirt and I could feel her rubbing herself through her shorts.

"God Sue, I'm going to cum."

"Me too," she replied.

Then I was gasping and moments later there was a large wet patch on the front of my slip and a similar damp patch in Sue's shorts.

We collapsed on her bed and when we recovered we sorted ourselves out. Me with clean panties and another slip and Sue had changed her shorts and boy's briefs. Seeing her wearing boy's briefs made me realise that Sue is much more tom-boyish than I had realised.

That day we both learnt a lot more about ourselves and each other than we had known before.

"I'm sorry I came in my panties" I said "but you got me so excited"

"Well Paul," she said "or should I call you Paula."

"Call me Paula." I replied.

"So Paula, we will just have to have a lot more dressing practice, don't you think.

I agreed, and Paula was born.