The Baseball
Much of the novel is tasked with tracing down the origins of the baseball claiming to be the same ball hit into the stands by Bobby Thomson in the Shot Hear 'Round the World. The ball is originally grabbed Cotter Martin before being stolen and sold by his father, Martin in the same night. From here, the story grows tangled and complicated though the ball ends up in the ownership of Marvin Lundy, who spent years tracing down the ball. He eventually sells it to Nick Shay for a large sum of money. Though the ball cannot be guaranteed to be authentic, these men invest large sums of time and money regardless.
Cleanliness of Garbage
Nick Shay's job is in waste disposal and treatment. He details large, odorous mountains of trash which rise like mountains. They are unruly and indomitable. Yet at the same time, Shay details the way in which his household deals with trash. They sort each item with incredible precision. They are boxes and bags for each type of object, be it plastic, aluminum or compost. It is ironic because although Shay spends a considerable amount of time sorting the waste at home, he also sees how it ends up in the trash mountains at the end of the day.
The "Perfect" Family
Shay is vocally proud of his family. He loves his wife and admires his two children. Whereas his own youth was spent in an unstable familial environment, he seeks to change that with his own family. They take road trips and vacations, and at face value it they seem to have an ideal American family. Meanwhile, Nick's wife Marian is engaging in an extramarital affair with his colleague and has taken to smoking heroin. He believes his family is functional, but beneath the surface there is deep dysfunction.
Privacy and Presentation
Nick's younger brother Matty worked in the American Sun Belt on a top secret nuclear weapons program. In order to do so, he signed a non-disclosure agreement akin to a gag order. He was sworn to secrecy about even the most minute aspects of his job and was not even able to tell his girlfriend exactly what he did. Yet through his narrative, he divulges every secret of his job. He talks about his occupation and the objectives of the program. He addresses conspiracies about nuclear testing and even admits to consuming marijuana. Although he is sworn to professional secrecy, he is incredibly candid in his narrative.
J. Edgar Hoover and Sexuality
The real-life character of J. Edgar Hoover has long been dissected and analyzed, and in Underworld, DeLillo continues the tradition. He assumes the man's head space and speaks from the first person. As DeLillo suggests, Hoover displayed homosexual tendencies going so far as to position a mirror in his hotel room to watch his assistant, Clyde Tolson, undress. Here DeLillo directly addresses the problematic irony. Throughout his career, Hoover participated in the persecution of suspected homosexuals, with his administration outing individuals and shaming them out of the jobs. Despite this, Hoover himself was possibly homosexual.
The Gangster Trope
In the workplace, Nick Shay often acts out a comedic bit. He assumes the voice of an Italian gangster and threatens to harm someone if they do not complete tasks or get their work done, as though a character in the Godfather. His coworkers admit to enjoying the bit. Later in the novel, Shay admits that his son has begun listening to rap music and has taken to dressing as the stereotype of a modern gangster with baggy jeans and a backwards ballcap. Whereas Nick jokes about being a gangster because it is so unlike himself and does it as a joke, his son dresses like a gangster in the hopes of finding a sense of self-definition and person-hood.
