Irish playwright and novelist Sebastian Barry is the only writer to have won the Costa Book of the Year award twice: first in 2008 for The Secret Scripture and again in 2016 for Days Without End. As with much of Barry's writing, the starting point for both of those books was someone in his own family. In his novels, plays and even his poetry, Barry creates a richly inventive world filled with his relatives and family stories.

Days Without End is inspired by Barry's grandfather's great-uncle, who emigrated to America as a teenager in the mid-19th century to escape the Great Famine. It also reflects Barry's feelings about his own son, who was 16 years old when he told his father he was gay. The novel follows the story of a young Irish-American immigrant, Thomas McNulty, and his partner, John Cole, as together they survive the brutality of the Indian Wars and later the Civil War.

Sebastian Barry spoke to Eleanor Wachtel from London, England.

People had trouble in the 19th century. A lot of people left on these six-week boat journeys, for whatever reason, in the great emergency of the famine. But a lot of people just disappeared — they just vanished. They never came home, they never wrote a letter and nothing was ever heard of them again. But there was this one person that news got back from at some point. This man had been off in one of the Indian Wars, somewhere in the 1850s or '60s. But when [my grandfather] said that to me, it was literally half a sentence. It was "My great-uncle was a cavalry soldier in the Indian Wars." That's all. That was it. I was eight years old at the time.

25 years [later], I wrote a little play called White Women Street. It was my first effort to think about this man. By then I was worried about it because I was thinking, well, what is it about this Irishman, a person who had been through the colonization of his country and yet he goes over to America, escaping the famine, and lands in a place where the only work he can get is soldiering. He's really good at soldiering, but it's engaged, initially, with the utter destruction of this amazing culture and people that we know of as Native Americans. That bothered me a lot.

Then it took me another 25 years, more or less, to try to be on his side about it, to let him tell his story and for me to not be so interested in the politics. That was a liberation for me, because when you let a person be their own self, with their own complicated issues, the real ember of their humanity is, I think, blown upon. It puts a breath upon his ember and the little fire of his former existence. It makes a clearer mark on the night.

These are people about whom nothing is said, and for good reason. I snatched them out of time. I feel that very much, that I stole them out of the air, that they not only have no existence, but in a way have no business to be. So it's the unwritten accounts of these people that I suppose I am trying to supply. My desire as a human survivor — and we're all survivors, we try to be — is to get some of these documents necessary to my survival, even if I have to make them up.

He illuminated me. He shone a light into me. I had to conclude that to be gay was not something that should just be so-called "tolerated," but something to be emulated, something to be learned from because the exactitude, for instance, of his relationship with his young beloved was so impressive to me as a human being that I felt utterly privileged to observe it. It's not that I put it into the book — the book drew it in. It became a fatherly undertaking to show, as clearly as I possibly could, the possible majesty of that relationship. I was very, very proud. I dedicated the book to [my son], and you can imagine my immense pride, not just as a father but as a creature on this earth, when he said, "Well, Dad, you're not gay, but you're an ally." And I thought, there's a war worth being an ally of.