No Real Names

In Chapter 10 of Slaughterhouse Five we find out that Vonnegut and Billy Pilgrim were in the same place at once. Vonnegut says, “Now Billy and the rest were being marched into the ruins by their guards. I was there. O'Hare was there.”(Chapter 10)So when at the begging of the book Vonnegut states he won’t say real names, “I've changed all the names.”(Chapter 1) he was talking about Billy, as well as O’Hare. Before I thought O’Hare was the actual name, but since I read the last pages and his named appeared I remembered that Vonnegut had changed all the names. Also if Billy Pilgrim and Vonnegut where together in Dresden, it might mean Billy Pilgrim is just a man who’s story was written by Vonnegut, not necessarilly a friend, or even Vonnegut himself.