The many similarities between E.L. Doctorow's Billy Bathgate and William Kennedy's Legs suggest that Doctorow used Legs as a starting place for the creation of his own novel. Certain scenes are so similar that it seems that they did not originate independently. Marcus Gorman and Billy Bathgate had almost indistinguishable experiences while firing target practice and later when Jack Diamond and Dutch Schultz died. Doctorow did not, however, merely copy Kennedy's story; he instead used it as a building block to begin from. Billy Bathgate had many elements that Legs did not which expanded the story's significance.
The pistol firing scene in Billy Bathgate palpably mimics the machine gun practice in Legs. Not only are the literal actions very similar to each other, but their impact on the characters is almost identical as well. The excitement and power gained by firing weapons lures both characters further on their descent into the criminal underworld. After shooting, Marcus thinks, "Do something new and you are new. How boring it is not to fire machine guns" (Kennedy 41). And Billy said, "I will never forget how it felt to hold a loaded gun for the first time and lift it and fire it, the scare of its animate kick up the bone of your arm, you are empowered there is no question about it, it is an investiture, like knighthood" (Doctorow 145). In the case of Marcus Gorman, the exhilaration of firing the machine gun was the benefit that would outweigh the risks of associating with Jack Diamond. Billy had already been attracted to the gang life. However, the power he gained from firing his automatic amplified his attraction. He finally understood why the other gang members had such closeness with their guns. Doctorow saw Marcus' introduction to the gang life through guns as an organic element in the story that worked properly. Therefore, he chose to borrow for Billy rather than trying to come up with something different that may not have worked as well.
After their gun firing experiences, Marcus and Billy experienced many strikingly similar events. The most dramatic of these were the death scenes of Jack Diamond and Dutch Schultz. In both cases, mentor and protégé were together at the time of departure, and each protégé received a privileged transmission of information that no one else did. Jack Diamond finally succumbed to the many bullets early in the morning in the quiet and solitude of his apartment. But, his spirit lingered as Marcus was not yet ready to say goodbye. The final words of Jack's spirit before it finally departed were said to Marcus: "Honest to God, Marcus… I really don't think I'm dead" (Kennedy 317). Marcus had received something from Jack that would allow a piece of him to go on living, something that no one else had received. Jack endowed Marcus with enough of his own life to keep himself from really being dead. Dutch Shultz and Billy Behan's final conversation was also a conversation between the dead and the living. After somehow managing to sneak undetected into the hospital room of one of the most notorious gangsters of the day, Billy sat for over two hours listening and writing down what his mentor had to say. It was nonsensical talk that no one else could understand, but Billy deciphered it. Death followed soon after the speech and Billy was the first to see Dutch Schultz dead. But, Dutch had not completely left yet. "My mind flashed with an entire normal conversation between us, the one it was too late for, his confession and my forgiveness, or perhaps the other way around, but in either case the conversation you only have with the dead" (Kennedy 311). Billy Behan and Dutch Schultz had a connection so strong that it was able to transcend the boundaries of death, just as Marcus Gorman and Jack Diamond's had. The story would not have been the same without these post-death experiences. Because it was a vital part of Legs, Doctorow needed to include it into Billy Bathgate in order to give his story that same depth.
Why did Doctorow choose to borrow so much from Kennedy's story? I cannot say for sure because I am not him, but I imagine that it is because he saw the brilliance in Legs and wished to take it to a further level. Rather than starting completely from scratch, Doctorow used Legs as a block for his story to stand upon in order that it might reach higher levels. However, I must emphatically state again that Billy Bathgate is not merely a copy of Legs -- there are entirely new elements present in Doctorow's story that were not in Kennedy's. The most important of these was the narrative of Billy's journey into manhood, an addition that added a whole new dimension of significance to the story. Additionally, Doctorow explored the relationship between sanity and craziness through the introduction of Mary Behan and introduced mythical and political metaphors that further strengthened the impact of the novel.
Many of the new elements in Billy Bathgate revolve around Drew Preston. Her character probably evolved from that of Kiki Roberts. But, Drew's role greatly outshone her predecessor's and she came to have one of the most significant roles in the novel. She was responsible for Billy's metamorphosis from a boy to a man. This coming-of-age theme becomes the main focus of the novel. Early on, we find Billy on top of the orphanage roof paying Rebecca to have sex with him. The sex was purely physical, a business transaction, and there was no emotion involved. It was sex between children. The lovemaking between Billy and Drew was completely different. They were intimate and loving and their sexual encounters were much more than just physical acts. They sparked new life, a baby boy that would make Billy a father. He recalled that when he first saw the child, "I felt a small correction in the just universe and my life as a boy was over" (Doctorow 322). Having a child is the most significant part of our human lives. And so by displaying Billy's entrance into fatherhood, Doctorow added a new significance to the story. His is not a story about Billy's involvement with the gang; it is the chronicle of how Billy became a man, a much more meaningful tale. By combining the excitement of the gangster world that Kennedy introduced to us in Legs with such an important step in human life, Doctorow was able to make Billy Bathgate a very powerful book.