Balzac's style in Le Père Goriot is influenced by the American novelist James Fenimore Cooper and Scottish writer Walter Scott. In Cooper's representations of Native Americans, Balzac saw a human barbarism that survived through attempts at civilization. In a preface to the second edition in 1835, Balzac wrote that the title character Goriot – who made his fortune selling vermicelli during a time of widespread hunger – was an "Illinois of the flour trade" and a "Huron of the grain market". Vautrin refers to Paris as "a forest of the New World where twenty varieties of savage tribes clash" – another sign of Cooper's influence.
Scott was also a profound influence on Balzac, particularly in his use of real historical events as the backdrop for his novels. Although history is not central to Le Père Goriot, the post-Napoleonic era serves as an important setting, and Balzac's use of meticulous detail reflects the influence of Scott. In his 1842 introduction to La Comédie humaine, Balzac praises Scott as a "modern troubadour" who "vivified [literature] with the spirit of the past". At the same time, Balzac accused the Scottish writer of romanticizing history, and tried to distinguish his own work with a more balanced view of human nature.
Although the novel is often referred to as "a mystery", it is not an example of whodunit or detective fiction. Instead, the central puzzles are the origins of suffering and the motivations of unusual behavior. Characters appear in fragments, with brief scenes providing small clues about their identity. Vautrin, for example, slips in and out of the story – offering advice to Rastignac, ridiculing Goriot, bribing the housekeeper Christophe to let him in after hours – before he is revealed as a master criminal. This pattern of people moving in and out of view mirrors Balzac's use of characters throughout La Comédie humaine.
Le Père Goriot is also recognized as a bildungsroman, wherein a naive young person matures while learning the ways of the world. Rastignac is tutored by Vautrin, Madame de Beauséant, Goriot, and others about the truth of Parisian society and the coldly dispassionate and brutally realistic strategies required for social success. As an everyman, he is initially repulsed by the gruesome realities beneath society's gilded surfaces; eventually, however, he embraces them. Setting aside his original goal of mastering the law, he pursues money and women as instruments for social climbing. In some ways this mirrors Balzac's own social education, reflecting the distaste he acquired for the law after studying it for three years.
Le Père Goriot, especially in its revised form, marks an important early instance of Balzac's trademark use of recurring characters: persons from earlier novels appear in later works, usually during significantly different times of life. Pleased with the effect he achieved with the return of Rastignac, Balzac included 23 characters in the first edition of Le Père Goriot that would recur in later works; during his revisions for later editions the number increased to 48. Although Balzac had used this technique before, the characters had always reappeared in minor roles, as nearly identical versions of the same people. Rastignac's appearance shows, for the first time in Balzac's fiction, a novel-length backstory that illuminates and develops a returning character.
Balzac experimented with this method throughout the thirty years he worked on La Comédie humaine. It enabled a depth of characterization that went beyond simple narration or dialogue. "When the characters reappear", notes the critic Samuel Rogers, "they do not step out of nowhere; they emerge from the privacy of their own lives which, for an interval, we have not been allowed to see." Although the complexity of these characters' lives inevitably led Balzac to make errors of chronology and consistency, the mistakes are considered minor in the overall scope of the project. Readers are more often troubled by the sheer number of people in Balzac's world, and feel deprived of important context for the characters. Detective novelist Arthur Conan Doyle said that he never tried to read Balzac, because he "did not know where to begin".
This pattern of character reuse had repercussions for the plot of Le Père Goriot. Baron de Nucingen's reappearance in La Maison Nucingen (1837) reveals that his wife's love affair with Rastignac was planned and coordinated by the baron himself. This new detail sheds considerable light on the actions of all three characters within the pages of Le Père Goriot, complementing the evolution of their stories in the later novel.
Balzac uses meticulous, abundant detail to describe the Maison Vauquer, its inhabitants, and the world around them; this technique gave rise to his title as the father of the realist novel. The details focus mostly on the penury of the residents of the Maison Vauquer. Much less intricate are the descriptions of wealthier homes; Madame de Beauséant's rooms are given scant attention, and the Nucingen family lives in a house sketched in the briefest detail.
At the start of the novel, Balzac declares (in English): "All is true". Although the characters and situations are fictions, the details employed – and their reflection of the realities of life in Paris at the time – faithfully render the world of the Maison Vauquer. The rue Neuve-Sainte-Geneviève (where the house is located) presents "a grim look about the houses, a suggestion of a jail about those high garden walls". The interiors of the house are painstakingly described, from the shabby sitting room ("Nothing can be more depressing") to the coverings on the walls depicting a feast ("papers that a little suburban tavern would have disdained") – an ironic decoration in a house known for its wretched food. Balzac owed the former detail to the expertise of his friend Hyacinthe de Latouche, who was trained in the practice of hanging wallpaper. The house is even defined by its repulsive smell, unique to the poor boardinghouse.