How has The BFG's life changed by the end of the novel?
The BFG tells Sophie early in the novel that he has been around for so long that he does not remember how he came to be. He guesses that he simply appeared around the same time that the earth was created. We learn at the beginning of the novel that his life has been the same for a very long time; he catches dreams, eats disgusting snozzcumbers, and watches glumly as the other giants go off to kidnap and gobble up local children. He seems somewhat lonely and not particularly happy, but it has been this way for so long that he doesn't seem to be able to imagine any other way of life.
However, things start to change when Sophie enters his life. She introduces him to new ideas and makes him realize that his life could actually be better. These changes start out small. When The BFG tells Sophie how much he hates eating snozzcumbers, she asks him if he really NEEDS to eat it. He replies, "You do unless you is wanting to become so thin you will be disappearing into a thick ear." He seems to believe that snozzcumbers are literally the only alternative to eating "human beans". Sophie opens his eyes, though, by telling him, "We don't have to eat snozzcumbers. In the fields around our village there are all sorts of lovely vegetables like cauliflowers and carrots."
These changes become more dramatic when Sophie decides that they simply must do something to stop the giants from guzzling up children. The BFG has never let a human being see him before because he was convinced that they would lock him away or hurt him, but Sophie convinces him to walk right up to the Queen's window and introduce himself. She also convinces him to stand up to the other giants, which is something he has always been too afraid to do on his own.
By the end of the book, The BFG has completely embraced an entirely new way of life. He is considered a hero by many leaders of foreign countries - is even given an elephant, his most precious desire, by the Ruler of India! The Queen of England has built him a house fit for a giant right next to her castle, and a small cottage right next door for Sophie. The BFG even learns how to read and write, and we find out at the end of the novel that he is actually the author of the novel itself! Nearly everything about The BFG's life has changed, and it appears that he will continue living a very happy life for a very long time.