Folken Lacour de Fanel is the elder brother of Van Fanel, the young king of the kingdom of Fanelia. As the firstborn son, he was the original heir to Fanelia's throne. His life took a decisive turn when he underwent the traditional rite of passage required to become king: a ritual hunt to kill a dragon. During this fight, Folken failed to slay the beast, and the dragon tore off his right arm. Although the dragon left him alive, Folken was consumed by shame over his failure. He was rescued by the Zaibach Empire, where Emperor Dornkirk provided him with a sophisticated mechanical replacement for his lost arm. Choosing not to return home, Folken joined the empire and rose to become its chief strategist, serving as Dornkirk's right hand.

In terms of physical presence, Folken is a tall and composed young man. His most defining physical characteristic is his artificial right arm, a complex piece of machinery that replaces his entire natural limb. He shares the same Draconian heritage as his brother, meaning he possesses a pair of large, black-feathered wings that he can summon at will and use for flight. This heritage is often a cursed and hidden secret in the world of Gaea.

Folken is an intensely complex and intelligent individual. To the outside world, and especially to his enemies, he often appears cold, calculating, and ruthlessly efficient. He speaks in a calm, measured tone and rarely displays strong emotion, which can be mistaken for heartlessness. In truth, Folken is a deeply compassionate and caring man. He is tormented by his past and driven by a sincere desire to create a better world. He abhors unnecessary violence and barbarism, preferring diplomacy and strategic planning to senseless slaughter. This inner conflict is the core of his character: he commits cruel acts, such as approving the destruction of his own homeland, not out of malice, but because he believes they are necessary sacrifices for a future of lasting peace. He is a tragic figure who is perpetually torn between his role as a loyal commander of the Zaibach Empire and his love and loyalty for his younger brother, Van.

His primary motivation is the pursuit of a world without war and suffering. This dream aligns him with Emperor Dornkirk, who seeks to manipulate the very fate of Gaea to achieve absolute peace and happiness for its people. Folken joins the emperor in this quest, believing that by controlling destiny, the endless cycle of tragedy can be broken. He is willing to get his hands dirty, justifying his terrible actions as a means to a greater, more benevolent end. He ultimately wants to free people from what he sees as an archaic and cruel system of tradition and fate, including the barbaric rites of his own kingdom.

Within the story, Folken initially occupies the role of a primary antagonist. As the strategist of Zaibach, he orchestrates the empire's military campaigns, including the invasion of Fanelia. However, his role is nuanced from the beginning. He consistently refuses to kill his brother when he has the chance, instead trying to persuade Van to join his cause willingly. He uses his position to protect those he cares about and to gather allies who have suffered, like himself. As the series progresses and he witnesses the tragic consequences of the empire's methods, his faith in Dornkirk's path wavers. He experiences a profound redemption arc, eventually turning against the emperor and sacrificing himself to help Van and his friends defeat Dornkirk and save Gaea.

Folken's key relationship is with his younger brother, Van. Despite their opposing allegiances, Folken's love for Van is the anchor for his morality. He is deeply protective of him and longs for his forgiveness and understanding, wanting Van to see that they both desire the same thing. Another significant relationship is with the cat-like sisters, Naria and Erya. Folken saved their lives when they were orphaned children and has since become their protector and commander. They are fiercely loyal and devoted to him, though he sees them more as precious friends and allies rather than as romantic interests. He also shares a deep intellectual alliance with Emperor Dornkirk, whom he respects as a mentor and visionary, even as he ultimately comes to reject his inhumane methods.

Folken's character development is one of the most compelling arcs in the story. He begins as a seemingly cold-blooded villain who destroyed his own home. As his backstory is revealed, he transforms into a sympathetic and tragic anti-villain. His true nature as a caring, idealistic man who was broken by tradition and saved by a false promise is exposed. The turning point is the death of Naria and Erya, which forces him to confront the real cost of his and Dornkirk's plans. He acknowledges his mistakes and willingly joins the heroes to atone for his crimes, finally finding redemption through self-sacrifice.

Folken possesses a wide array of notable abilities. His primary strength is his immense intellect; he is a genius-level strategist, a skilled sorcerer, and an adept engineer or chemist who contributed to many of Zaibach's technological advancements. He is a capable swordsman, though he rarely fights on the front lines. His mechanical right arm grants him various hidden functions, though it is also a constant reminder of his past failure and a source of some physical hindrance compared to a natural limb. As a member of the Draconian race, he can manifest his black wings to fly, a power he typically hides due to the social stigma attached to his people.