Hermes, also known as Lord Silvermask, is a central figure and a primary antagonist in the story. Born as the sole son of King Osroes, he was the rightful heir to the throne of Pars until his uncle, Andragoras, seized power. As a child, Hermes was left for dead in a burning palace set ablaze by his uncle's machinations, an event that scarred the right side of his face horribly and instilled in him a deep, lifelong trauma regarding fire. He survives the assassination attempt and is taken in by others, eventually resurfacing years later as a high-ranking commander in the army of Lusitania, the nation that has invaded his homeland.

Driven by an all-consuming ambition and a burning desire for revenge, Hermes is ruthless and willing to commit any atrocity to reclaim what he believes is his birthright. He is cruel, short-tempered, and bears an undying hatred for King Andragoras, finding satisfaction in the pain of the man who destroyed his life. He holds an unshakable conviction that the throne of Pars is his by right, and he becomes enraged that skilled warriors like Daryun and the strategist Narsus choose to follow the young Prince Arslan instead of him. Despite his villainous actions, his past as a wronged prince makes him a sympathetic figure, and his struggle against the man who stole his crown is portrayed as deeply personal and almost tragic.

In the events of Dust Storm Dance, Hermes breaks away from the Lusitanian leadership to pursue his own claim to the throne. His primary goal becomes the retrieval of the legendary sword Rukhnabad, a royal symbol he believes is his by right, which leads him into direct conflict with both the Lusitanian fanatics and Arslan's forces. He commands fierce loyalty from followers like his retainer Sam and the young knight Xandes, attracting them through a combination of his legitimate claim and his formidable strength. However, his inability to inspire loyalty or see beyond his own ambition is a consistent weakness. Unlike Arslan, who gathers allies through compassion and wisdom, Hermes rules through fear and a sense of entitlement, which drives many potential supporters away.

Hermes is an exceptionally skilled swordsman, considered one of the most powerful warriors in the series. He is capable of matching or even defeating legendary fighters such as Daryun and the master Vahriz, often leading his forces from the front of the battlefield with devastating effect. His only notable weakness is his crippling fear of fire, a psychological scar from the attempt on his life that can be exploited in combat. Over the course of the story, his vengeful obsession is shown to consume him, gradually revealing that his cruel actions and narrow focus on the throne have made him a less suitable ruler than the man he seeks to destroy, even as his tragic origins earn him a measure of the audience's understanding.