Over the course of the play Hieronimo undergoes radical transformation from a loyal, trusted, and comfortable courtier in service to the King of Spain into a murderer. He becomes "mad" not only because of the murder of his only son and his inability to obtain justice for this crime, but also because of the disintegration of civil law and the indifference of the Duke of Castile. As a trusted administrator of justice, it is Hieronomo's duty to make sure justice is done to others, even when that same justice is denied to him. And as a devoted father and husband, the loss of his only son and the consequent suicide of his wife Isabella drives him into the spiral descent by which he determines that the "wild justice" of direct revenge is the only course of action available to him. Civil redress doesn't work because Horatio's murderers are more highly ranked than he and his family and therefore immune from punishment. In the throes of single-minded vengeance, Hieronimo at first pretends to be mad in order to throw off his enemies, allowing them to believe all their ambitions will be fulfilled only moments before he arranges for their deaths. When words and images fail to express his pain and frustration, he resorts to the illusion of a play to complete his revenge in reality.
Ghost of Andrea
The Ghost of Andrea posits the "question" in the play, "How will my death be avenged?" With his assigned guide and companion, Revenge, he serves as the Chorus present throughout the entire play. A noble and loving knight to his more high-ranking lady in life, Andrea fulfilled his duties as both a valorous warrior and an attentive lover; he was the ideal courtier who is equally capable in these opposite roles. However, this capacity made it difficult for the judges of the Underworld to decide which reward in the afterlife would best suit him: the abode of fallen warriors, or the abode of the lovers. His presence and commentary during the play sets the tone of oppositions that drive the course of the action by which, in due time, his death on the battlefield is revenged. Even so, the Ghost of Andrea is not very patient, and he constantly berates Revenge for taking so long in completing the task.
An entity of the underworld, Revenge is the "answer" to the Ghost of Andrea's "question" and, with him, provides the Chorus. As the personification of a quality, Revenge's ultimate purposes are obscure and puzzling at first, because there seems to be no limit to the time frame in which Revenge takes action; sooner or later makes no difference whatsoever. This quality frustrates the Ghost of Andrea, who wants to gain immediate and forceful restitution. But as an "immortal" force, Revenge acts in his/her own time to work through all the layers of his instrument, Hieronimo, even as Andrea's murderer comes within arm's reach of fulfilling his passion to gain Bel-Imperia. In this way Revenge restrains the Ghost of Andrea until a full and completely devastating conclusion to injustice can be made.
A young man, Horatio is barely 19. He is honest, brave, and chivalrous on the battlefield as well as in romance, a devoted and obedient son, and loyal knight to Spain. It is his valor on the battlefield that first impresses Balthazar, who would like to have been placed in his custody when captured, instead of that of Lorenzo. Horatio's care of the remains of his fallen comrade in battle inspires Bel-Imperia's admiration of him, as the two of them progress from warm friendship to lovers. Without guile or deception himself, Horatio easily falls victim to the plot to kill him. His altruism completely baffles Balthazar and Lorenzo, who think him weak and easily duped. At the same time, his gentle self-confidence is something they both fear and fail to understand.
Highborn, beautiful, and imperious, Bel-Imperia is accustomed to getting what she wants. She enjoys lovers who are not her equal in rank and will not put up with obstacles to her passion. She is the key to the play, because she is the reason her first knightly lover, Andrea, has gone to war—to win honor in her eyes. Once Andrea has been killed by Balthazar, she easily transfers her affections to his best friend, Horatio. She wants love and romance, but her station in life demands that she be given as wife to the highest bidder—Balthazar, whom she cannot stand. Bel-Imperia plays a game ruled by powerful men as best a woman of her time can. She makes coy shows of submission to her father's wishes and pretends to cozy up to her murderous brother so that she can goad Hieronimo into revenging Horatio's death. She, almost as much as Hieronimo, is stripped of all pretense of civil behavior by the end of the play. It is she who avenges Andrea's and Horatio's deaths by killing Balthazar and taking her own life as well.
Weak and vain, Balthazar can make a pretty speech and actually seems to enjoy his role as the rejected lover. He is easily manipulated by his new friend, Lorenzo, and the two of them conspire to murder Horatio. Although a prince of Portugal, Balthazar is determinedly single-minded in possessing the love of Bel-Imperia, and the more she rejects him the more ardently he pursues her. He takes for granted the privileges of rank and fails to understand that genuine love doesn't yield to promises of wealth, position, or power. In the end he doesn't seem to care one way or the other how Bel-Imperia feels about him as long as he can possess her as his wife. The implication is that if she had not killed him and herself, he would have made her pay dearly for giving her love to someone else.
Outwardly boastful and cruel, Lorenzo deceives everyone with plausible lies and manipulates Balthazar's infatuation with Bel-Imperia. A young man of ambition and anxious to promote his own glory over others on the battlefield, Lorenzo uses the battlefield to make a show to everyone else of having what he really lacks; a sense of honor and courage. Always uncertain of himself, and trying to take from others what he suspects he doesn't have, Lorenzo believes he is clever enough to control Balthazar once Balthazar has married his sister and gained the crown. This situation far better suits Lorenzo's talents than actually being in line for the crown himself, as it is a much safer position from which to wield power. As for love, Lorenzo has no idea how deeply Bel-Imperia is devoted to her ideal of romance or the extent to which she is willing to go when denied her desire. Spoiled and indulged, Lorenzo thinks nothing of using underlings and discarding them in order to distance himself from scandal and dishonor.