Pablo is the leader of the band of guerillas who are supposed to aid Jordan in the demolition of the bridge, the central action of the book. When the reader first encounters Pablo, he finds the man to be sullen and uncooperative, wanting neither himself nor his men to have any part in Jordan's assignment. In a "showdown" with Pilar, his mujer, Pablo is forced to abdicate his leadership of the band, and the men decide that they will help Jordan. Pablo's moroseness persists until, on the night before the bridge is to be blown, he runs away. He returns, however, in time to aid in the attack on the bridge.
Hemingway seldom allows a scene, or a piece of action, or a bit of dialog to carry only a single meaning. In the same way, he seldom permits his major ideas to be represented by a single character. Though, at first, Pablo and Jordan seem to be greatly dissimilar, as the book progresses, the reader becomes increasingly aware that the two men are basically alike. Both men are experiencing the same sort of transition, the major difference being that Pablo has progressed farther along the scale than Jordan. He has already accepted those realities of the war to which Jordan has been trying to adapt himself, and he has already lost that fervor which he had at the beginning of "the movement." In addition, Pablo is less willing than Jordan to deceive himself about the possibility of doing the bridge assignment successfully.
Sick of the war and unwilling to die for the cause, Pablo deserts, an action which is thematically parallel to Jordan's later contemplation of suicide. But, again paralleling Jordan's action, he returns because he is the only one who can lead the group to safety after the battle. "Having done such a thing [i.e., deserted]," he says, "there is a loneliness that cannot be borne."