Azar Nafisi, the author of Reading Lolita in Tehran, had once said that a novel is the most democratic form of literature because it gives voice and agency to a multitude of characters. I liked this idea and imagined a literary stage of people controlling their own fates.

My writer friends thought this was ridiculous. Who do you think holds the puppet strings?

I confess: I did not write Tanya Tania. At least not by myself. It was always the girls, crowded around me, their breath mingling on the back of my neck, itching to get their hands all over the page. They always succeeded. My novel is democratic, yes, but is it mine?

Tanya Tania is a novel set in Bombay and Karachi in 1992, written in letters. Tanya Talati in Karachi is reflective and ambitious, Tania Ghosh in Bombay is brash and sexy. They disdain needing anyone or anything (other than Harvard and parental approval) and yet find themselves telling each other what cannot be said to anyone else – a city turning alien, a mother fallen silent, desires that don’t fit.

I don’t remember having a plan to write the novel in letters. To be honest, I had no plans at all. I thought I would see where it goes.

“Dear Tania,” I wrote, on behalf of Tanya, “I am the daughter of your mother’s best friend.”

“Dear Tanya,” wrote back Tania immediately, “You sound boring.”

I looked at what I had written, surprised. I wrote again. “Between school and keeping my mom off my back and trying to keep my boyfriend from having sex with me (or anyone else), I really don’t have time to write to you.” I stopped again, amazed and more than a little wary. Where had that come from?

It took a page for the girls to form. Within five, they held the strings.

I wrote most of Tanya Tania last monsoon in Arrosim, Goa, a small, rain-battered beach that was always empty except for a motley group of wet dogs who growled half-heartedly, a black and white mottled one coming over to sniff my laptop every day as if one day it might smell different. The solitude of the beach and the ferocity of the monsoon swells must have seemed an invitation to Tanya and Tania because they took over the stage, arranging people, stories and places with clear plans and hard passion.

If I had lost control in Chapter One, by Chapter Three, I was their puppet, writing and rewriting until they were satisfied. Tania is insistent, Tanya is stubborn. Tania changes her mind often, Tanya not at all. As the monsoons grew more intense, it became impossible to take my laptop to the beach anymore and I sat up late at night in the balcony, a black raincoat pegged up to the clothesline, pillows arranged in a desk, already deeply in love with the two girls, wishing for them to succeed, wishing I could save them from the things that they were planning to do to themselves.

And yet, like a twist in a Chekhov story, the democracy of this novel hadn’t, even then, fully emerged.

Chhoti Bibi and Nusrat, two girls who work in the houses of Tanya and Tania, had been characters in my story from the beginning, coming attached, like a suitcase, each to their own Tanya/Tania. But I had never thought that they would become major characters. And yet, as the pages grew, and the storm clouds gathered over my little rented flat by the sea, Chhoti Bibi and Nusrat stretched and grew, stretched and grew. I found myself talking seriously (and aloud) to Tanya and Tania at three in the morning in a lull of rain, asking them if this is what they wanted. This was meant to be your story, I reminded them. Yes, they said, this is our story. Ours.

And so I learnt the hardest lesson of democracy – that your agreement means nothing. Here I had set out to write a novel about my heartbreak over the Bombay riots of 1992, about the walls and wires between India and Pakistan, about how I never understand how Hindus and Muslims live together and don’t live together, often in the same moment in time. But the story I wrote instead was about girls.

Girls and their mothers, girls and their fathers, girls and their sex, girls and their ambitions, girls and their power, girls and their love. Identity, like an elastic band waxed and waned – sometimes wrapped tight around one person, even just one part of one person, sometimes stretching to include a family, a neighbourhood, a religion, a language, even a city. And when I stopped being anxious about who was writing my story, I realized that this, after all, was exactly what I had wanted to say.

The first time the novel ended, I went to the shack on the beach where I had alternately ordered Gobi Manchurian and Porky Chilly Fry through the summer and ordered a double gin and tonic. Justin, the skinny, punk-haired boy with an earring behind the bar, slid it across to me grinning.

As the sea crashed outside, the last line of my book dissolved into tears that slid dirtily into the drink, leaving a salt train on the thick soda-water-bottle glass. “What’s wrong?” asked Justin. I looked at his brown eyes (was that kohl in the corner?) and thought about how to tell him about my sadness at the end of Tanya and Tania, Chhoti Bibi and Nusrat.

“My friends,” I said to him. “My girls have left.” His face relaxed and he patted my hand. “That’s all? Arey madam, they will be back no.”

It’s been more than a month since I’ve opened Tanya Tania (my editor has forbidden me). Stories I read, things I see remind me of them and sometimes when I’m lonely, I call them to see if they will come play with me. Sometimes they do.

My hope for Tanya Tania is that the girls inhabit other lives. That they take on different paths and voices for different people, touching memories I cannot, lighting jokes I do not know and soothing wounds I cannot see. I don’t think I could have shared them otherwise, my four girls of 1992, running crazily through the rain on a Goa beach, laughing at me, teasing me, taking my story away and away from me and running with it, far, far, farther and farther ahead until I can barely see them, lost somewhere between the sand and the sky, between Bombay and Karachi, four vanishing points in the Arabian sea.

Anatara Ganguli’s novel Tanya Tania is now open for pre-orders.