He is an unconventional protagonist for a war novel, Billy is weak, passive, and often ridiculous. He is totally unsuited for war, and he nearly dies wandering behind German lines during the Battle of the Bulge. After the war, he becomes an optometrist, marries a rich girl, and comes to believe that aliens called Trafalmadorians have abducted him. He is "unstuck in time," meaning that he experiences the events of his life out of order again and again.
Billy Pilgrim in the Essays