As the son of an English parson, Jim grows up in a secure environment where he is free to construct romantic adventures in which he is the hero, always ready, always victorious, and always adhering to a strict moral code of behavior. His heroic aspirations draw him toward a life at sea. Here, Jim encounters brutal realities he cannot control and which seem to render powerless the noble code by which he lives. Jim's failure to act courageously and honorably during a crisis at sea shatters his self-image and alters the trajectory of his life. Jim has a mythic quality. Storyteller Marlow says he often seems to glimpse the essence of Jim as if "through a rent in the mist in which he moved and had his being." Throughout the novel, Jim appears through the eyes of others. Like an impressionist painting made up of multi-colored dots, Jim's character is a collection of conflicting impressions. Jim appears strong, yet weak; noble, yet cowardly; self-confident, yet insecure. He looks "as genuine" as a newly minted gold coin, but there lurks "some infernal alloy in his metal." Jim is described as an inch or two under six feet, strong, with "blue, boyish eyes," curly fair hair, and a tendency to blush. At emotional moments, he is often at a loss for words. However, "there [is] a high seriousness in his stammering," and his words are deeply felt and hold deep meaning.
Captain Marlow is about 20 years Jim's senior, an experienced seaman, and the narrator of Jim's story. In the course of his professional career at sea, Marlow has trained young men like Jim for their maritime service. He sees in Jim the essence of youth, "on the brink" of life and adventure, "looking with shining eyes" upon the glitter of the vast ocean—a glitter "which is only a reflection of his own glances full of fire." Marlow is drawn to Jim's youthful idealism while repulsed by his criminal desertion of the Patna. He experiences a mix of sympathy and antipathy regarding Jim—sympathy because Jim's naïve, romantic illusions reminds Marlow of his own youthful dreams; antipathy because Jim has violated the time-honored moral codes held dear by "the community of mankind." In the moment of Jim's deepest despair, Marlow steps in to help him, assuming the role of benefactor and father figure. He is someone Jim can trust and who wishes to help him regain what he has lost in the wake of the Patna incident. Simultaneously, Marlow becomes a conduit for bringing Jim's story to the world that has harshly judged and rejected him. He relates Jim's story as seen through his own eyes as well as the eyes of others, such as Captain Brierly, Stein, and Jewel.
Montague Brierly is a 32-year-old captain in the mercantile marine with an impeccable record of service. Also known as "Big Brierly" among his peers, he has risen steadily in his career and is everything Jim aspires to be. Brierly has never made a mistake, never had so much as a mishap, and seems to "know nothing of indecision much less of self-mistrust." In Marlow's initial judgment, Brierly is rock-solid, at ease with himself, and impervious to "the sting of life." Therefore, it comes as a shock when, a week after the court hearing concludes, Brierly commits suicide. Brierly is an assessor, or judge's assistant, at the court hearing concerning the Patna. The case greatly disturbs him, especially as Jim is the only officer to accept the full brunt of accusations of cowardice and dereliction of duty. Brierly asks Marlow why Jim is willing "to eat all that dirt." For Brierly, the Patna incident represents everything he abhors. It is an abomination and "enough to burn a man to ashes with shame," particularly as it involves a dreadful violation of trust. "Such an affair," he tells Marlow, "destroys one's confidence." Marlow suspects Brierly's suicide connects to a secret moment in the captain's past when he similarly failed the moral code by which he lives; that as the captain judges Jim's case, he simultaneously holds "silent inquiry into his own case" and cannot live with the verdict of "guilty."
Stein enters Jim's life three years after the Patna incident. Jim has been fighting a losing battle to restore his self-respect and pursue his heroic dreams. Stein immediately recognizes Jim to be a romantic because he, too, once held and lived by romantic ideals. At age 22, Stein fled his homeland after involvement in a failed revolutionary movement. Within the Malay Archipelago, he found work assisting a Dutch naturalist collecting insects and birds. Four years later, Stein inherited a prosperous trading business on the island of Celebes from a dying Scotsman. Eight years of heroic exploits and adventures followed, during which Stein married a native princess. However, when she and their young daughter died of fever, Stein left the country he could no longer bear. He started life afresh in Samarang, becoming a successful trader and renowned entomologist specializing in butterflies and beetles. Stein has led the kind of life Jim has read about in books and has dreamed of for himself. Stein knows what it is to chase a dream and capture it. He also understands the devastation an individual experiences when he realizes he cannot achieve his dreams. After Marlow asks Stein for his help with Jim, Stein proposes to drop Jim into the remote island setting of Patusan where he will be free to pursue his noble and heroic fantasies. He can leave "his earthly failings behind him" and discover "a totally new set of conditions for his imaginative faculty to work upon."
Brown is the rumored son of a low-ranking English baronet and often refers to himself as "Gentleman Brown." He began his life as a modern-day pirate by jumping ship in Australia during the gold-mining days. Within a few years he was known as the terror of Polynesia. In time, his luck went sour and he was driven from the South Seas toward the Philippines. Now he sails into Jim's story. A streak of sadism runs through Brown's history of piracy, kidnapping, and murder. He has "a vehement scorn for mankind at large and for his victims in particular." When the villagers of Patusan repulse his attempted invasion, Brown determines to punish them no matter the cost. Brown hates Jim without reservation, detesting "his youth and assurance, his clear eyes and his untroubled bearing," along with the unshakable moral code Jim exemplifies. Jim represents everything Brown has despised and defied his entire life. For Jim, a man like Brown is a shock and a danger to all he has worked to achieve on Patusan. He is a messenger from the outside world—a world Jim has renounced; a white man from "out there" where Jim does not feel "good enough" to live. Brown makes up his mind: before leaving Patusan, he will destroy Jim. In this way, he becomes the catalyst for Jim's death.