I first met Frank Moorhouse in the early 1990s when I was living in New York. We were in Washington to speak at an event I remember as being improbably titled the Festival of Australian Ideas (oddly, no one mentioned the Hills Hoist or the Esky). We hit it off over dinner. The fact that I told him I fell in love with his writing as a teenager may have affected his judgment.

I grew up in the working-class beachside town of Newcastle with left-leaning liberal minded parents. His early books were on our shelves, and I read them. The author will be forever best-known for his wonderful protagonist Edith Campbell Berry, of the Edith trilogy, but his earlier short stories gave me a glimpse of a different world: an exciting bohemia in the Sydney suburb of Balmain where actors, journalists, writers, artists and film-makers all knew each other, socialised and fought for social justice. I remember telling a bemused 15-year-old friend that when I grew up I wanted to be Frank Moorhouse.

I still wish I’d been born a decade earlier so I could have been part of the 70s liberation movements – particularly the second wave women’s liberation. On my return to Sydney, Moorhouse and I continued our friendship and he generously mentored me as I began publishing my own books. One of his great legacies was the extraordinary mentoring he showed to emerging writers such as Matt Condon and Julia Leigh.

After I wrote a profile of him for the Bulletin in 2004, Moorhouse rang me to say it was the first piece someone had written that he thought really captured him. He told me I “got him”. The conversation about writing his authorised biography began.

Ten years ago, I embarked on serious research for the book – a process that inevitably tempered our relationship – and we came to an agreement. He would give me full access to everything in his archives and factcheck all the chapters, but not ask me to redact anything.

He kept to his side of the bargain and over a decade I spent many weeks in the Moorhouse archive in the Fryer Library, assisted by Simon Farley and his amazing team of research librarians. Moorhouse’s wonderful archivist Nicholas Pounder accompanied me on a number of my expeditions into the 158 boxes of material.

I was astounded by the volume of material in the archive. Moorhouse kept a copy of every significant letter he ever wrote and received. He also kept weird things, like aeroplane food menus from the 1970s and old American Express card receipts. There is a lot of material in the archive which I chose to leave out; I didn’t want to out some of his gay lovers, or hurt them or their families.

Moorhouse was a bisexual cross-dresser who grew up in a time when homosexuality was criminal and cross-dressing was considered unnatural. He had a strong personal objection to the bourgeois insistence on conformity and privacy. I once asked him to send me a list of everywhere he had lived and who he was in a relationship with. He also included a list of exactly what kind of sex he was having with his partners in great detail. “Way too much information Frank,” I told him.

He had many lovers, and long-term relationships with women and men. One day I was reading a voluminous file which began with a letter from a woman I am very close to, academic and writer Fiona Giles. She was 17 when she met Moorhouse, already an accomplished author. He was 37. Their correspondence traced the emotional, intellectual and explicitly sexual contours of a relationship that spanned 13 years, and ended with an unsent suicide letter to her from Moorhouse, when she finally ended things. I found myself standing in the sandstone quadrangle of the University of Queensland sobbing, and called her to tell her what I had just read. “Darling, you’re the biographer, you have to read everything,” she said. “Better you than some horny old Marxist.”

The breadth and depth of Moorhouse’s contribution to Australian literature, to activism and to fighting for writers’ rights is extraordinary. In a case that went all the way to the high court of Australia, Moorhouse agreed to lend his name to an action against the University of NSW, for allowing students to breach authors’ copyright by photocopying their work. The same thing was happening across schools, libraries and tertiary institutions across the country.

Peter Banki, one of Australia’s foremost copyright lawyers, and his partner David Catterns had approached Moorhouse over a martini or two at the Sydney Hilton’s Marble Bar. “Let me get this straight,” Moorehouse replied. “I put my name on a case in which we prosecute school teachers, librarians, university lecturers, and school and university students? Essentially alienate most of the serious readers of books in this country.”

They won the case, and writers are now paid for the copying of their work through fees collected by the Copyright Agency. It was a courageous thing for Moorhouse to do.

Moorhouse was a writer who thought deeply about ethics – the ethics of writing and the ethics of being human. He often drew people around him into his stories. But they were equally fictional characters. Like the brilliant writer Helen Garner, he was more inclined to scrutinise himself than others. And it would be a mistake to take his characters literally.

Moorhouse died on 26 June 2022, at the age of 83. His close friends Nick and Carol Dettmann and Sandra Levy were with him in his last hours. I’d only just posted on Facebook that I had begun writing the closing chapter; the next day I opened my account to find a comment from his close friend, literary critic Don Anderson, telling me Moorhouse had died. He had read all of my chapters except the conclusion.

Five minutes later the phone rang: a journalist asking me to comment on his death and his legacy. Still in shock, I responded: “Well bloody Frank always had to have the last word”.

There will be many other books written on Moorhouse; Matthew Lamb is currently writing one of them. All will shed different light on one of Australia’s finest authors whose career spanned the novel, the short story, the essay, the memoir, the erotic novella, screenplays and historical monographs. He even invented a literary style: the discontinuous narrative.

Moorhouse lived 13 lives in one. And there is so much more to be said about his stories, and the complex storeys that were housed inside one our finest authors.

• This article was amended on 26 August 2023 to reflect that it is the Copyright Agency that collects and pays copyright fees, not the Australian Copyright Council.

• Frank Moorhouse: A Life by Catharine Lumby is out on Tuesday 29 August through Allen and Unwin