“Camerados” details the relationship between Walt Whitman, the 19th century American poet, and Peter Doyle, an Irish immigrant who grew up in Richmond, Va., enlisted in the Confederate Army and, in the waning days of the Civil War, became the love of Whitman’s life. “Camerados” tells its story through the transformation of hundreds of documents, including Whitman’s poetry, that are in the public domain. Its methodology takes cues from the somewhat Brechtian approach pioneered by Moises Kaufmann in “Gross Indecency: The Three Trials of Oscar Wilde” and “The Laramie Project,” but bends that approach to very different ends because it has a very different story to tell. So what was America’s great literary champion of Abraham Lincoln doing bedding down with a former Rebel soldier young enough to be his son? That’s what “Camerados” is all about.