The two principal characters are typical Verne creations. Otto is described by Axel as “a learned egoist” and “a hoarder of knowledge”—“there really are professors of this kind in Germany,” he adds. Fifty years old, a distinguished academic and a remarkable linguist, Otto is restless, impulsive, secretive, eccentric, and, at times, foolishly irrational. He is less sympathetic than the scholarly Professor Aronnax of Vingt Mille Lieues sous les mers (1870; Twenty Thousand Leagues Under the Sea, 1874) and rather more like the fascinating, demoniac Captain Nemo of that great book. Axel is entirely Otto’s antithesis; youthful, romantic, knowledgeable enough about scientific fact and theory to challenge his mentor’s assumptions, he is the perfect foil to his uncle. While always loyal and respectful to Otto, Axel’s privately expressed anxieties and wistful reflections mark him as a more fully human protagonist than his companion.
Of the minor characters, Hans is the most important. He seldom speaks, never complains, and stolidly accepts his role as guide and general handyman to the expedition. His sole demand that he be paid his wages at regular intervals strikes the reader as mildly absurd, given the dangers of the enterprise. Yet Hans’s physical strength and manual skills lend plausibility to the story and complement the intellectual natures of Otto and Axel. He is Verne’s common man. Grauben has little to say or to do, underlining the fact that in a Verne novel there are no strong roles for women. The remaining minor characters—the Lidenbrock housekeeper, a professor in Reykjavik, and a few more—are merely functional figures of no intrinsic interest. One should not ignore, however, the ghostly presence of Arne Saknussemm, hovering over events from first to last. His intriguing testament is both a spur to action and a constant reminder of the resourceful human imagination and courage the author so evidently admired.