Hermes is the head of the Hermes Familia, a prominent group in the city of Orario. As a god, he is several million years old and, like other deities, has descended from Heaven to live among mortals, though he often leaves the day-to-day management of his familia to his captain, Asfi Al Andromeda, due to his restless and wandering nature.

On the surface, Hermes presents a personality that is casual, playful, and overwhelmingly charming. He is incredibly sociable, open, and confident, often seen with a relaxed smile and a lighthearted demeanor that makes him seem like a carefree and irresponsible god. He typically avoids direct confrontation and prefers to maintain a neutral position in most disputes, focusing instead on his role as an entrepreneur who deals in high-quality merchandise and information. However, this jovial exterior masks a far more complex and calculating nature. In truth, Hermes is exceptionally sharp, shrewd, and cunning, capable of becoming utterly serious when the situation demands it. He is a master manipulator who has no qualms about outwitting both mortals and his fellow gods to see his plans come to fruition. A notable, often comedic flaw is his perverted streak; he shares the beliefs of Zeus that it is a man's duty to peep on beautiful women bathing and openly enjoys such activities.

The driving force behind Hermes's actions is a deeply held, almost fanatical belief that the world is in desperate need of a new, true hero. His primary motivation is to identify, cultivate, and witness the rise of this hero, a figure he believes is essential to save the world. He is a loyal follower of the god Zeus, who was also Bell Cranel's adoptive grandfather, and much of his interest in Bell stems from this connection and Zeus's request to check on the boy. Hermes is dedicated to forging Bell into that hero, even if the methods required are morally questionable. He is willing to expose Bell to the dark and grotesque side of the world as a test of his character, believing that if the boy breaks under the pressure, he was never meant to be a hero. He sees major conflicts and crises in Orario not as disasters but as opportunities to push Bell's growth further.

Hermes's role in the story is that of a schemer and an instigator who works from the shadows to shape events. He has a profound fascination with Bell Cranel, and a significant part of his narrative function involves engineering situations to challenge the young adventurer. For instance, he mischievously arranged a peeping incident that led to Bell accidentally seeing Ais Wallenstein naked, and he also devised a plan to help Bell dance with her at a ball. More seriously, he played a pivotal role in the destruction of the Ishtar Familia by cleverly manipulating both Ishtar and Freya. During the conflict involving the Xenos, the intelligent monsters of the Dungeon, Hermes showed his most ruthless side. Although he was cooperating with Ouranos to protect the Xenos, he was willing to sacrifice several of them and stage a public battle to restore Bell's ruined reputation, demonstrating that his loyalty to Bell's heroic ascent supersedes all other alliances.

His key relationships are central to his character. He is a faithful subordinate to Zeus, sending him regular reports and carrying out his requests regarding Bell. His relationship with Asfi Al Andromeda is one of deep reliance; he trusts her implicitly to lead the familia in his absence and to execute his complex plans, having rescued her from a difficult former life. His dynamic with Bell is the most critical, as he acts as both a friendly ally and a hidden puppet master, pushing Bell toward his destiny as a hero regardless of the cost. He maintains a working relationship with the god Ouranos, though their goals are not fully aligned, as Hermes dismisses the idea of peace between humans and monsters as a fantasy.

Over the course of the series, Hermes's conviction regarding Bell only solidifies. After observing Bell's actions on the 18th floor of the Dungeon, he becomes absolutely certain that Bell is the hero the world has been waiting for. This leads to an unwavering, and sometimes ruthless, determination to support him, even if Bell himself comes to hate him for it. He will clash with allies and employ dirty tactics, such as forging maps or using magical artifacts to manipulate situations, all in the name of creating a legendary hero. His development is less about personal change and more about the escalating lengths to which he will go to achieve his singular goal.

In terms of notable abilities, Hermes's power does not lie in direct combat, as gods in the mortal world are forbidden from using their divine power (Arcanum). Instead, his strengths are his intelligence, his unparalleled skill in information gathering and manipulation, and his eloquence. The Hermes Familia itself functions as an information network, collecting secrets from across Orario to be used as leverage. He is also a renowned traveler, capable of moving freely inside and outside the city, and his familia possesses magical artifacts, such as Asfi's flying boots, which he often commandeers for his schemes. His true power is his ability to orchestrate the actions of others, turning the entire city into a stage for the hero he is determined to create.