IT WAS 15 years ago when Fábio Moon discovered Brazilian author Milton Hatoum’s book “Dos Irmaos” (Two Brothers) and was pulled magnetically to its subject matter. Moon is Brazilian, too, and he himself has a twin brother — Gabriel Bá, the other half of an Eisner Award-winning fraternal duo. And after reading the book, Moon was convinced he’d read a future classic. Still, this wasn’t a work he considered adapting.

Nine years later, though, at a literary convention in Brazil, Moon would have his mind changed. There, he and his twin brother were introduced to Hatoum by a publisher, who believed the acclaimed author of a tale about Brazilian twins needed to meet with two Brazilian twins known for making comics. Talk turned to adapting “Two Brothers” as a graphic novel.

Hatoum thought it was a great idea with much potential, but the twins weren’t so sure it would work. “We were not excited [initially] because we knew the story was very complex,” Moon told The Post’s Comic Riffs.

In the story, Brazilian-born Lebanese twins let a mentally and physically scarring moment from their childhood launch a lifelong silence and sometimes physical war between the two. The work is told in a stream-of-consciousness; narrative that isn’t so readily converted into comics.

“It’s very hard to translate visually,” Moon said. “The drawings could easily mess up the rhythm of the reading experience and spoil the story. And it was such a big, complex story that we thought it would be too much work.”

Yet the challenge was tantalizing. One appealing aspect was an opportunity to show a too rarely seen part of Brazil’s past in Manaus, the Amazon city where the book is set.

So taking up the challenge, the next decision was: Which brother would draw the story?

“We usually decide which one is going to draw because we have different

styles, so that the book will have one look and not two different styles to distract the reader,” Bá told Comic Riffs of “Two Brothers,” which is newly released by Dark Horse Comics. They decided that Ba would handle art duties and that they would work as co-writers, given that Moon provided the artwork for their last project, the Eisner award-winning “Daytripper” for Vertigo Comics.

In breaking down the tale, Bá and Moon plunged deep into understanding Omar and Yaqub, the novel’s titular twins.

“They hate each other,” Bá said of Omar and Yaqub. “They’re opposites. One doesn’t want anything to change, and the other goes after all the changes that are going on in the world and tries to adapt to it. One is very shy and keeps everything for himself, and the other is very open in the wild.

“I think it’s a way of playing the differences between them and trying to increase the tension of the book.”

One recurring element is how the story’s supporting characters consistently believe the twins will somehow come to a reconciliation. “The fact that they are twins makes people expect them to get along, think alike and everything to work out,” Moon said. “They get more different by the time the story progresses, but still, the characters around them and the readers, they want them to get along and everything to work out because they are twins.”

Hatoum made himself available to Moon and Bá for creative questions, but they only needed to consult with the author twice. The first time was during their first-ever visit to Manaus, nearly a six-hour flight from their hometown of São Paulo. That trip helped them gain visual insight into the world they would render.

And the second time, Hatoum intervened and became somewhat insistent. When the twins showed him the initial sketches of “Two Brothers’ “main characters, Hatoum liked every single design save one: the twins’ mother, Zana. “He had a completely different idea of Zana than what we presented. Our idea of Zana was much more of this sensual gypsy kind of woman,” Bá said. “He showed us some family pictures of women in the early 20s and 30s and those images, they matched the research we were doing, but we didn’t want to accept that women [in Brazil] were like that back then. The idea we had in our minds was [much] stronger and different.

“But when he talked about it and showed us pictures and talked about who this character was and what she meant, we understood better,” Bá continued, “and that helped us create a new visual for her and understand her role in the story with the other characters and the reader as well.”

Another twist in Moon and Ba’s bringing “Two Brothers” to life visually was their decision to present the multicultural world of Brazil without color. “We chose to do [this] in black in white because of the poetic power that black-and-white art has and can add to the story,” Ba said. “We thought that it would add up to the style of the story.

“It demands more from the artist and from the reader. They have to make a bigger commitment to read and to translate that art into understanding the world. So it gives a more powerful reading experience.”

And then there can be the unintended consequences of color.

“Color can be very distractive,” he said. “We didn’t want to distract the reader with colors all around, with the nature and the buildings and the rivers. In the same way you can tell a story full of colors and make the reader imagine it … in a prose book, we thought we could do it on a comic book as well with black-and-white art.”

And then there is the two brothers’ own creative approach. Unlike when Moon and Ba are separately working with others in the comic-book industry, they can be brutally honest with each other without fear of offending. It is a trait the twin’s share that they are both grateful for.

“We don’t care about hurting each other’s feelings at all,” Bá said. “We can say anything. We can be brutally honest about work. If [Fabio] is angry, that will last five minutes tops. And we move on.

“We can’t help it. We are stuck with each other for the rest of our lives.”