Kurt Vonnegut Jr, in Slaughterhouse Five, relates many stories that are essentially biographical, although the characters are fictional. Billy is the main character and, at the end of chapter one, the reader is introduced to the concept of Billy's time travelling as " Billy Pilgrim has come unstuck in time." The stories can be confusing as Billy often knows the outcome and so sees the events in reverse order, making almost philosophical statements, such as "all humanity, without exception, conspired biologically to produce two perfect people named Adam and Eve..."
Billy, having participated in the World War II effort, qualifies as an optometrist after the war, gets married and settles down, having a daughter and a son and a successful practice which belies his state of mind throughout the story. His wife dies tragically whilst he, himself, is recovering after a plane crash and has had to have brain surgery. He begins to relate the stories of Tralfamadore and their apparently enlightened theory of time, adopting the Tralfamadorians concept of death as representing only a moment in time, thus eliminating the significance of death. He accepts it and many things because "So it goes."
Billy served in the war as a chaplain's assistant and whilst wandering behind enemy lines, he joins up with a group of scouts. He returns to this story several times, in a random manner, as he and Weary, one of the Scouts, are captured and marched through the territory. Billy's unstable state of mind is evident as he swaps between the stories and the time periods; his capture by the Germans and his abduction by the Tralfamadorians and his optometrist practice. Billy's attempts to cope with serious traumatic events with a resigned acceptance are seen as Billy having accepted a Tralfamadorian way of thinking as he looks for positive outcomes in everything, especially in an effort to cope with his otherwise pointless existence. It is as if his experiences with the Tralfamadorians are as routine as his practice.
During his travels with the Tralfamadorians, Billy questions the concept of free will. The meaning of life is something he constantly struggles with. There is a common thread between capture by the enemy and abduction by the Tralfamadorians as he is, effectively, held against his will. The meaningless of his life does bother him and his awareness that he will be in a plane crash and he will die in 1976 only fuel his illusions. It seems he travels in time whenever any unpleasant memory or event takes place.
At the end of the novel, when he is recovering from his brain surgery, he says nothing at first, leading others to think he is a vegetable. He eventually speaks to Rumfoord about his time in the city of Dresden during the war. Billy leaves the hospital apparently cured of all his physical and mental scars.