My thought is that Tralfamadore is his imaginary world created to assist him in relating his painful recollections of the horrors of Dresden and him imprisonment during the War. I just completed with my brother-in-law and my wife, a book which details the true story of the bombing of Dresden. It details the story of the 150 Americans housed in Vonnegut's infamous Slaughterhouse Five in their own words. (Shadows of Slaughterhouse Five available through Amazon.com) After interviewing at least 80 of the surviving men over the last 13 years, we learned that each man dealt with the horror in their own way. As you have re-read Vonnegut's Slaughterhouse Five, the book takes on a greater meaning. Tralfamadore is his literary "almost protective device" to tell his story. Other characters in the book are based on fellow prisoners such as Billy Pilgrim and Edgar Derby.