The Youngest Son author John Byrnes was left a "bit spooked" after talking to his 93-year-old dad about his new book.
"This is the strange thing, in that, it's probably 20 per cent based on real stories that he's told me and 80 per cent of things I've either just embellished, or they've just come out of my own imagination," Byrnes told ABC News.
"I was talking [to my father about the book] just the other day, and he was telling me about things that I'm sure were just out of my imagination, and he told me [they] had actually happened.
"And it's kind of freaking me out a little bit. I thought it was good. But I kind of walked away a little bit spooked."
Billed as an epic saga of brotherhood, betrayal and revenge, The Youngest Son is exactly that.
"These are my father's stories," Byrnes said.
"My parents had children relatively late in life. My father was born in 1930. And he was orphaned by the time he was 13, his father died much earlier on, and then his mother died.
"And he was effectively brought up by a bunch of uncles, parts of whom, parts of which, make up some of the characters in this book."
Byrnes writes about the three siblings who make up the Leach family. Bob, a natural in the boxing ring, is the titular youngest son. But we learn just as much about his older brother John who is desperate to join the priesthood but torn by love, and sister Maureen, whose impoverished circumstances and questionable decision-making leads her to sex work.
Sydney, a vivid character in the book
The Youngest Son is mostly set in Sydney's seedy underbelly in the 1920s, 30s and 40s against the backdrop of the Great Depression and World War II.
Byrnes says his father's uncles "were all World War I veterans and men of that ilk," and the book explores battlefields far away.
"It's about overcoming adversity, and people living well below the poverty line, and how they live their lives and how things work out for them," he says.
Sydney of old comes alive within the pages of the book. You can smell it, taste it, feel it.
Byrnes was born in Marrickville but grew up mostly on Sydney's Northern Beaches.
"But if I go to Camperdown or Newtown or Marrickville, I don't know what it is, but I can feel it. I feel that's where I feel at home more than anywhere else," he said.
"It feels really familiar at a really deep level that I find hard to explain."
Byrnes daydreams for a living
Byrnes has a process of testing out various scenarios on the page until they feel authentic.
"I sit there and I daydream for a living," he said.
"And I just think things through until it feels real to me. And then I write that bit down.
"I really wanted to talk about things that are real, rather than look back as we tend to do and say things were so much better back in the day, because they weren't."
A fascination with the darker aspects of the human condition
Byrnes served in the Australian Army, has worked on fishing trawlers out of Darwin, worked in finance and worked bars and doors in pubs and clubs all over Australia.
His debut book was the 2023 Australian crime fiction novel Headland.
He says some of the positions he's held are good opportunities to observe people.
"It's weird when you're the only sober one in the room," he said.
"It's a fantastic opportunity to just watch humans at their best and their worst.
"And if you can sit back and absorb it, then there is just a rich, rich tapestry to draw on when you're writing.
"I find humans fascinating."
The Youngest Son by John Byrnes is available in bookstores, online and as an ebook and audiobook.