Four father-son relationships exist in The Assistant, three biological and one created. The created relationship exists between Morris Bober and Frank Alpine. Morris's biological son, Ephraim, died at a young age, but Frank arrives to learn Morris's trade and philosophy. Frank will be the one to inherit the grocery when Morris dies, which a son would normally do. The other sons and fathers demonstrate the difficult nature of passing on one's ethics and values to one's child. Jeffrey Helterman proposes that Malamud's presentation of four-father son relationships evokes the tradition of evoking four kinds of sons during the Passover Seder: the wise son (Nat Pearl), the wicked son (Ward Minogue), the foolish son (Louis Karp), and the son who has wits not to ask (Frank Alpine). Frank eventually does learn to ask the right questions and in doing so becomes more of a son to Morris Bober than the other sons are to their fathers. The way that these various relationships are explored in the novel touches on the relative difficulty of passing a historical legacy from father to son, as well as one's philosophy of system of laws.
Frank Alpine spends the novel learning to transcend the ignoble desires of his self and learn to be a good person. Frank's general tendencies, as exhibited in the beginning of the novel, lean toward dishonesty and lust for Helen. He desires to become like Saint Francis, a model of goodness, but it is only through a fierce struggle that he is able to do so. Morris Bober is a person who has learned how to transcend his self and proceed with grace. Morris Bober fully accepts the idea of suffering. He sees that it is necessary to his self and the world. Through his acceptance, Morris is able to transcend the imprisoning effect of his suffering and liberate his self. Frank Alpine's eventual transformation in the novel allows his to achieve similar spiritual freedom.
All of the characters in the novel are either immigrants or the children of immigrants. In the belly of New York City, they all struggle for the American Dream. Malamud suggests that this struggle is difficult, but also acknowledges its possibilities. Some immigrants, like Julius Karp, have managed to become rich. Although Julius is not an honorable person, his economic success came in part from his own hard work and his willingness to take advantage of the opportunities before his eyes. Nat Pearl represents another success story in the community. Although his parents still speak Yiddish, he managed to attend Columbia and now attends Law School. While there are these successes, there are also many difficulties. The Bobers barely subsist even though they own their own business. Carl, the Swedish painter, has children who appear to be constantly hungry. Even the tendency for customers to leave the Bobers' store for better prices seems reasonable given their economic struggle. Malamud exposes the possibility of realizing the American Dream as a new immigrant, but also its harsh reality by exposing the lives in an immigrant community in Brooklyn.