"How will I ever get out of this labyrinth?" (128before.120)
These are Alaska's favorite last words, and they're from one of her favorite books, The General in his Labyrinth by Gabriel García Márquez, which is a biography of Simon Bolivar. We never really know what the labyrinth is—that's one of the enduring mysteries of the novel—but Alaska thinks that it's about suffering.
"It's not life or death, the labyrinth."
"Um, okay. So what is it?"
"Suffering," she said. "Doing wrong and having wrong things happen to you. That's the problem. Bolivar was talking about the pain, not about the living or dying. How do you get out of the labyrinth of suffering?" (52before.9-11)
And in some ways, her thinking directs how the rest of the characters view the labyrinth. But for the Colonel, the labyrinth is something different. Or at least he thinks of it differently, because whereas Alaska wanted to escape the labyrinth, he chooses it.
"After all this time, it still seems to me like straight and fast is the only way out—but I choose the labyrinth. The labyrinth blows, but I choose it." (122after.12)
For Miles, it's not that he chooses the labyrinth, but he's found a personal way to escape it.
He was gone, and I did not have time to tell him what I had just now realized: that I forgave him, and that she forgave us, and that we had to forgive to survive in the labyrinth. (136after.9)
So what is the labyrinth? Life? The end of life? Suffering? We don't know, and in the end we have to define it for ourselves in the same way the characters each struggle with their own definition of the labyrinth. And just as each character's navigation of this question shows us something about their character, it just might do the same for each of us.