Red-haired and freckle-faced Alexander Ramsay, known as Alec, begins his relationship with The Black Stallion on board the ship. Alec pities the stallion and entices the animal with handfuls of sugar, a kind act that no one else attempts. The stallion has proved to be dangerous, likely to kill, and determined to batter down the walls of his stall. Alec persists because he dearly loves horses, and the Black is unlike any he has seen. The novel's thematic center is the relationship that forms between the caring, determined teenager and the unruly stallion. Layered into this relationship are themes of courageous self-reliance and maturation, beauty, nature, education, cooperation, and—on the other hand—competition.

The theme of maturation develops through Alec. Although he displays independent qualities when the novel begins, he becomes stronger as events unfold. Alec is largely defined by his ability to relate to the Black, who frees and exalts him. He feels "different" atop the Black, "like being in a world all his own." Companioned and empowered by the Black, who at the same time needs him, Alec develops unusual self-reliance on the island. He is brave, hopeful, and patient in the face of adversity. He wastes little time in regret or philosophical pondering. Instead, he concentrates on making nature supply shelter and food. When Mrs. Ramsay greets her son in New York, she marvels at the new, "calm, self-reliant look" in his eyes.

Themes related to nature and beauty are developed through the Black. The stallion behaves in many ways that are normal for a horse, but he possesses incredible powers. When he runs at Belmont, an observer exclaims that he "made the track record look like it was made by a hobbyhorse!" The Black reflects the duality of nature, beautiful and helpful and yet dangerous. He has "a wonderful physical perfection" with a "savage, ruthless spirit" to match. Because the Black represents the wild, free, and unconquerable side of nature, he forces Alec to continue to grow. "I'll control him—one of these days."

Alec's maturation is also fostered by Henry Bailey, the only other human character of any prominence. Henry, a retired jockey who facilitates Alec's desire to keep and train the Black, is more than just a surrogate father. He is a confidant who validates Alec's maturation by suggesting that they "work together just like partners." While Alec's father encourages responsibility by having his son do chores to pay for the stallion's upkeep, ultimately it is Henry who passes along the torch of manhood. Before the match race that dominates the novel's concluding scenes, Henry tells Alec: "Well, kid, you're on your own now." Henry speaks as a mentor, and in this capacity he reflects the theme of education.

The value of school is a given in the novel. Its importance to life is shown when Alec can identify, prepare, and eat island carragheen as a result of a remembered biology class experiment. At Flushing, Alec displays concern about his grades and is depicted in school. Before the match race, Mr. Ramsay has concerns for his son's fulfillment of school requirements. Alec agrees to race "under one condition—that I stay until I finish my exams."

Henry's helpfulness and Mr. Ramsay's acquiescence exemplify the theme of cooperation that permeates the novel. Conflict is not centered in problems among characters, who are largely stereotypical, but in Alec's struggles to overcome raw natural forces and to control the Black. Mr. and Mrs. Ramsay—both minor figures—offer no real objection to Alec's sessions with Henry and the Black. They seem strangely willing to let Alec keep and ride a stallion described...