My mother was a witch. This is not to say she was a bad person. She simply had a power, and instead of scourging herself in penance, flinging prayers to the ether to change something that couldn't be changed, she accepted and used that power. She was a fierce person my mother. She reminded me of the old tomcat who ruled the kitchen step. Indifferent. Self-possessed. Not to be trifled with. It is probably not the most flattering comparison I could make, but it is the most honest and gives you the best idea of her nature. My mother was the cat that has chosen to come in from the cold, but stays only so long as it wishes, always prepared to leave without a backward glance from people that have adored and cosseted it.

How else could I know to ask my father to give me the first hazel branch to touch his head on his way home? I would have liked dresses and jewels just like my stepsisters, of course I would, but my mother was perfectly clear with her deathbed wishes, and made quite sure I knew what to ask for.

She was a witch, my mother, and I'm one too.

So I planted the hazel branch and watched it grow to avoid my father's new wife. She was a proud woman, and brought with her two daughters, both of them pretty in a soft, decorative way. No fire in them, my mother would have said, sniffing disdainfully. My mother's element was water; she wore her troubles down or she circumvented them. Eventually, all things went the way she desired them.

I do not have my mother's will, her flow. I have fire. Too much of it, perhaps. So I did not reach an accommodation with my new stepmother. I did not make her welcome, as my father told me to do. I did not like my new sisters, for all they were pleasant enough. The trouble of being a witch, I suppose, is that you must always be suspicious of someone's motives. To be burnt is a painful way to die.

When my father died, I hardly noticed it. He was a merchant, always far from home; he was always a pale shape to my mother's energy. I did notice when the books in the library disappeared. I noticed when the fine furnishings went the way of the books. I noticed that my two sisters got new dresses (I did not care to notice the circumstances behind them, the knowledge that my stepmother went upon bended knee for them, begged and borrowed and played the widow in impoverished circumstances). I noticed that my own jewellery, inherited from my mother, started going the same way as the books, and my stepmother found me one day holding sharp scissors, the new dresses my stepsisters would never wear in tatters around me.

When friendship with my two stepsisters would have proved useful, I found I had already burned that bridge. They were good people, but loss of wealth to those who have always known security is terrifying, makes for short tempers and short patience, and besides, it was their new dresses I had quite unrepentantly reduced to rags.

During the day I belonged to the fire and the hearth; I learnt baking and fire keeping and scullery keeping, all the arts of fire that I was pleased to learn and earned me the contempt of my sisters. At night I went to my mother's tree and danced as my mother danced, I did magic as my mother did magic, and I was happy enough.

Of course it would not remain that way. My mother's magic was strong, and would not let it stay so. She was water, and all obstacles would be passed.

I was jealous, when I went to my mother's tree and asked her to let me go to the ball. I was seventeen and I wanted to dance, I wanted to know what my sisters found gratifying in the gazes of men, I wanted to know what it was to be a normal girl for once, just once.

So I wore the dress my mother provided, put on the shoes gilt with gold, tied my hair and strung it with jewels as she planned for me to. I stood and I went and I danced like fire set loose at last. I danced with the prince. There was no choice in the matter – he was the prince; how could I say no? So I danced with the prince till the stroke of midnight, hoping until the very moment the clock struck that he would let me go, let me dance with someone else on my night of freedom, let me be free. I danced and danced and I hated him in the same breath that I loved him, for my mother's magic was water and mine was fire and in something so powerful as love we must always be at odds.

When the clock struck midnight, I ran home, and I flung my dress away and cursed my mother and her magic, for I knew I would return the next night, and the next. And so I did, though every time I hoped my mother's magic would loosen its hold on him, let me be for just a few hours to dance with someone else, anyone else, whoever I wished – is it not funny, how upon being given a maid's dream I wanted it to go away?

On the third night I ran away I still held hope that this was simply an interlude in my life, just three sparkling days of magic to be looked over with fondness one day in the far future – ah, my children, I could have been a princess if I wished. Except that I did not wish.

But my prince is cunning and my mother strong, determined to give me a happy ending, to give me the best that could be asked for of life.

He smeared the steps with pitch, and one of the fine shoes my mother's doves gave to me left my foot and stuck there, and no amount of pulling would loosen it.

Home in the kitchen, looking into the ashes to see what future was foretold there, I saw nothing but mud.

When men came to my stepmother's house bearing the shoe, I waited in the scullery while my sisters panicked and hoped and surveyed their feet with an odd mix of pessimism and hope.

I knew it would not fit them. Made with magic for my foot it would always be too big or too small for any foot but mine. But I did not want to marry a prince. I had danced with him, and I had enjoyed it. But to marry the man? All my mother's power could not convince me entirely that was what I wanted. I did not want to be a princess or a queen, to be constrained and moulded and forced into being aristocracy. My mother would have been able to manage it, but I am fire, and such an existence would reduce me to ashes.

So when the younger of my two stepsisters entered my kitchen, weeping, I saw a way out. You could see it in her face, her desperation to leave, to find that happy ending. "Please, please help me," she said. I remembered her weeping into her pillow, I remembered her mute and red-faced under her sister's acid tongue, I remembered her choosing last of all gifts, her sister always choosing first. I wanted to help her, for she was the kinder of my two stepsisters, and I wanted to hurt her, for I am a vengeful person and do not forget wrongs. It occurred to me that the two things were not entirely incompatible.

"Give me your foot," I said. I did not lie and say it would not hurt.

"Hold still," I said.

"Bite down," I said.

The crunch of blade against bone was very like the crack of chicken joints.

I helped her out of the kitchen, milk-pale and her ankle bound tight. "She is faint at the thought of seeing her prince again," I told them, and watched them help her upon her horse and I hoped the prince would be fooled.

A manservant told me later that one of the doves in my mother's tree began to sing as they went past

(turn and peep, turn and peep there's blood within the shoe)

but the aide de camp, weary and near-breakdown from a futile search said flatly that one of them had to have seen the blood seeping through. I cursed my mother's magic that day, to make a shoe as clear as glass.

(the shoe it is too small for her, the true bride waits for you)

When my elder stepsister stepped into the kitchen, I did not need her to talk and I did not need time to be sure of my intent. I sent her out in the same state as her sister; I made them equal for the first time in their lives.

I knew already she would fail, but I am fire, and I do not care who I burn.

My mother's doves sang and sent the search party back to the house where I waited.

The wedding passed in a torrent of lace, dressing and undressing, absurdly extravagant, the dress so covered with jewels and the train so long I could take only mincing steps forward, the crown so heavy I could barely lift my head.

I said my vows and I wept and perhaps my prince took them for tears of joy, as the populace did, and my head spun from all the strange phrases and the echoes from the cathedral walls, the mess of cooks and tailors and maids all seeking my approval, the Queen staring at me with her coolly appraising eyes, clearly wondering what sort of princess I would make.

I wondered too. My prince did not wonder. He led me to the bridal chamber and taught me what he wished me to know.

"You are not permitted a knife," he said. "You are not permitted a blade, you are not permitted a sword. I prefer my fingers and toes as they are – numbering ten and attached to me. Do not mistake me for your relatives."

"You do not sweep, you do not build the fire, you do not cook, you do not clean. These are things servants are for."

"You may not leave the palace grounds without an escort," he said.

"You do not need to visit your mother's tree," he said. "It will be dug up and replanted on the grounds."

Do this. Do not do that.

You are queen, not a servant. You are a doll, not a person

I was fire, but my mother was water and now I am ashes.