Vargas was a doctor-turned-rebel who devoted the final seven years of his life to killing the Slug Count.
Despite his disconcerting appearance, Vargas was a kindly man who wished well to everyone he met, with the exception of the Slug Count. Meeting Guts during the latter's days as the Black Swordsman (wherein Guts is less mindful of other people's opinions or feelings), Vargas was subjected to humiliating abuse at Guts' hands, such as having his cane kicked out from under him. Despite this, Vargas never lashed out against Guts and instead seeked to ally with him, knowing that the Black Swordsman possessed the skills needed to defeat the Slug Count.
Vargas also took an active stance in the defense of innocents: when Zondark raided Vargas' laboratory in search of Guts, Vargas shielded Puck with his own body from the falling debris caused by Zondark's whip-like attacks. Through his interactions with Puck, Vargas began to entertain the idea of abandoning his revenge in favor of moving on with his life, but was captured and killed before he could ponder the thought further.
As the Slug Count's court physician, Vargas became disgusted by his employer's barbarous inquisition – the Slug Count violating and eating supposed heretics – and promptly attempted to flee the Slug Count's castle with his wife and children in tow. However, Vargas and his family were apprehended and returned to the Slug Count, who kept them locked in a dungeon. He was forced to watch as his wife and children were dismembered and eaten, and was then mutilated himself. Before he too could be killed, Vargas managed to fake his own death and escaped the dungeon with the Slug Count's beherit. For the next seven years, Vargas despised the Slug Count and wished to kill him, but lacked the physical ability to kill the apostle himself.
Black Swordsman Arc Edit
Vargas first encounters Guts during the latter's escape from the Slug Count's soldiers and aids in his getaway with the use of smoke bombs, having witnessed his duel with Zondark and realized that the swordsman's fighting prowess is more than capable of defeating the Slug Count. He escorts Guts and Puck to his underground laboratory, revealing the beherit in his possession. When Guts demands to know the beherit's origin, strangling the deformed man in the process, Vargas insists that the fetish is not his; he stole it from the Slug Count. He then tells the travelers of his past leading up to their meeting in order to clear his name. After finishing his story, Vargas exclaims that he still does not understand the nature of the stolen fetish. In response, Guts explains that the object has manipulated the dark side of human history since ancient times, and that it acts as a key to summon the God Hand.
Vargas grabs hold of Guts' shoulder and pleads with him to kill the Slug Count in his stead, and Guts, displaying an aversion to being touched, kicks the man back. While he takes Guts' bad attitude and abuse without complaint, Vargas forms a more mutually well-meaning bond with Puck, who feels pity for him, and eventually shields the elf from the destruction caused by Zondark's second duel with Guts. Following Zondark's defeat, Vargas shows Guts a way out of the sewers and into the castle. Before departing with the swordsman, Puck advises Vargas to give up his pursuit of revenge and to instead live for the future, which the latter begins to consider. However, he is quickly captured by the Slug Count and put up to be publicly executed in a ploy to draw out Guts. Puck frantically urges Guts to save him, and when Guts refuses, remarking that Vargas is weak, Puck points out the truth: Guts is afraid because he sees similarities between himself and Vargas. In the face of Guts' inaction, Puck attempts to save Vargas himself, failing miserably and being captured in the process. Vargas' final words curse the Slug Count and promise retribution for his crimes, before an axe takes his head off.
Though dead, Vargas has an aftereffect on the swordsman and his elf companion, with Puck lamenting his inability to save an innocent life. Guts muses by himself on the similarities between Vargas and himself, though he denies them when Puck brings up the subject. When the Slug Count refuses to sacrifice his daughter, Theresia, and is dragged into the Abyss, Vargas is one of the first lost souls to bind him, fulfilling his oath of vengeance.
As the Slug Count's former physician, Vargas possessed a wealth of knowledge in the field of medicine. This knowledge ultimately allowed him to convincingly fake his own death and escape from captivity. He also apparently had knowledge in crafting smoke bombs, having used them to aid Guts in escaping a regiment of the Slug Count's guards.