Dunkler König Vearn, also known as the Great Dark King or the God of the Underworld, is the supreme ruler of the dark realm and the primary antagonist of the story. He is an ancient Darkling who has existed for thousands of years, and his entire existence has been defined by a deep and abiding resentment toward the gods and humanity. He believes that his people were unjustly banished to the dark and harsh environment of the Underworld while the weaker humans were gifted the sunlit Surface World. This perceived cosmic injustice fuels his grand ambition: to annihilate the Surface World entirely and redirect its sunlight to the Underworld, thereby ascending to become a true god who corrects this fundamental wrong.

In terms of personality, Vearn is the embodiment of a social Darwinist. He genuinely believes that power is the only law of the natural world and that concepts like justice, hope, and love are merely illusions created by the weak to protect themselves. He is a calculating and patient strategist, often comparing warfare to a game of chess where he meticulously orchestrates events from the shadows. Despite his cruelty, he possesses a sort of pragmatic fairness, offering his subordinates multiple chances to prove themselves. However, this is not born of loyalty; he ultimately views every member of his Dark Army, from the lowest monster to the Dark Lord Hadlar himself, as nothing more than disposable tools for achieving his goal. He shows a sadistic enjoyment in breaking the spirits of his enemies, taking pleasure in their despair before he grants them death.

Vearn’s role in the story is that of the ultimate hidden mastermind. He is the one who resurrects the Dark Lord Hadlar after his defeat by the hero Avan, granting him a more powerful body and tasking him with building an unstoppable Dark Army. This action sets the entire plot in motion. He also manipulates the Dragon Knight Baran, the father of the protagonist Dai, by exploiting his hatred for humanity after the destruction of the Alkeed Kingdom, recruiting him into his army. Unlike a typical villain who fights on the front lines, Vearn initially remains a faceless ruler behind a veil, only revealing himself and taking direct action when his plans begin to unravel after the fall of his commanders. His ultimate confrontation with Dai and his friends becomes a battle to decide the fate of the world.

Vearn has several key relationships that define his actions. His most significant subordinate is Hadlar, whom he revived and later betrays by implanting a "Black Core," a powerful bomb, inside his body as an insurance policy. This act of ultimate betrayal eventually causes Hadlar to turn against him. He also has a long-standing rivalry with Velzar, the King of the Abyss Dragons. After millennia of conflict, they agreed to a truce and a wager: whoever could conquer the Surface World first would earn the other's servitude. Vearn accepted Velzar’s assassin, Killvearn, as a "gift," treating the constant threat of betrayal as an amusing challenge. His relationship with the hero Dai is more personal; he attempted to corrupt Dai just as he did Baran, seeing the boy’s immense potential as either a powerful weapon or a threat to be eliminated.

Vearn's character undergoes a significant physical development throughout the story, shocking his enemies when his true power is revealed. To achieve immortality and accumulate power without the effects of aging, he performed a forbidden ritual to split his body into two halves centuries ago. One half contains his immense magical power and intellect, which was allowed to age and wither into the form of a frail, three-eyed old man. The other half is his youthful body, frozen in time and brimming with peak physical strength. This younger half was entrusted to his loyal servant, the shadow monster Myst, who merged with it to become the fears warrior Mystvearn. When the aged Vearn finally merges with his preserved youthful half, he undergoes a dramatic transformation into his "Wahre Gestalt" or "True Dark King" form. This true form is a towering, immensely muscular demon with long silver hair, straightened horns, and a simpler, more practical fighting outfit, discarding his crown and royal robes for a combat-ready appearance.

In this true form, Vearn's notable abilities reach their peak. He is one of the most powerful mages in existence, capable of casting high-level spells like Kafrizz and Kaboom instantly and with greater power than any other character. His signature magical attack is Kaiser Phoenix, an incredibly powerful firebird spell. However, in his true form, he predominantly relies on overwhelming physical combat techniques. He discards his Staff of Edacity, a weapon that converts magic into physical force, in favor of his own raw strength. His key techniques include Calamitous End, a devastating hand chop; Phoenix Wing, a parry that can deflect even powerful spells like Medroa; and his ultimate defensive and counter-attacking stance, the Demonic Guard of Heaven and Earth, which allows him to defend against and counter up to three different attacks simultaneously. As a Darkling, he possesses three hearts and incredible regenerative abilities, allowing him to survive wounds that would kill any other being. His third eye, the Sovereign Eye, is a source of immense magic that can be used to instantly seal weaker opponents into inanimate jewels or even force monster evolution. As a last resort, he can destroy his own Sovereign Eye to transform into his final form, the Sovereign Supreme—a gigantic, armored, crustacean-like monster of pure, brute force that sacrifices his magical abilities for unparalleled strength and durability.