Jade Curtis, originally born as Jade Balfour, is a colonel in the Malkuth Empire's military and serves as the commanding officer of its Third Division. He is a man of considerable intellect and ability, serving as a trusted right-hand to Emperor Peony IX. His reputation precedes him across the continent of Auldrant, where he is known by the ominous epithet "Jade the Necromancer," a name that reflects his controversial past rather than his current demeanor.

His background is defined by a genius intellect that isolated him from a young age. Hailing from the snowy city of Keterburg, Jade was a child prodigy whose brilliance far surpassed those around him. In his youth, he demonstrated a frightening detachment; his own sister, Nephry, would later describe him as a "devil" or a "demon" because he did not seem to comprehend the value of life, casually killing monsters for experimentation and disposing of them when they died. At the age of nine, he created a revolutionary scientific process known as fomicry, which allows for the creation of perfect copies, or "replicas," of any living or non-living entity. His first successful demonstration of this was creating a replica of his sister's broken doll rather than repairing it, an act that frightened rather than pleased her.

The most significant and tragic event of his past involved his mentor, Professor Gelda Nebilim, a healer who was able to command the Seventh Fonon, an element Jade himself could not use. In a failed attempt to master this seventh fonon, Jade caused a catastrophic accident that led to his teacher's death. Unwilling to accept her demise, he and his childhood friend Saphir (who would later become the God-General Dist the Reaper) used fomicry to create a replica of her. This attempt failed spectacularly, producing not a reincarnation of his beloved teacher but a monstrous, bloodthirsty copy that Jade was forced to seal away. This disaster led to a profound change in him; he eventually forbade the use of fomicry on living beings, recognizing its terrible ethical and technical dangers, and ceased his research, a decision that caused a permanent rift between him and Dist.

Jade’s personality is multifaceted and deliberately enigmatic. His default public demeanor is one of politeness, cheerfulness, and sharp sarcasm. He speaks to almost everyone with honorifics and maintains a constant, placid smile that gives little indication of his true thoughts. He possesses a dry, often cruel wit and finds amusement in teasing his companions, yet his jokes frequently carry a serious underlying point. Beneath this calm and genial exterior lies a deeply calculating and pragmatic soldier. He is ruthless when logic demands it, once preparing to finish off a helpless and unconscious enemy because leaving her alive would pose a future threat, a proposition that shocked his more idealistic allies.

Despite his controlled surface, Jade is haunted by his past. He feels immense guilt for the death of Professor Nebilim and for the horrific outcome of his attempt to revive her. He reveals a deep-seated envy for characters like Luke fon Fabre, who can understand what it means to die and to feel remorse for taking a life, concepts that have remained abstract to Jade. He admits that he still struggles to truly comprehend death, a deficiency he traces back to his monstrous childhood behavior. His journey with the party is in part a struggle to confront the sins of his past, which continually resurface throughout the narrative. By the story's end, he demonstrates significant personal growth, ultimately removing the special fon slot seals he had engraved on his own eyes to enhance his power, a symbolic act of discarding the dangerous and self-destructive methods of his past.

His key relationships are instrumental to his character. He shares a long history with Emperor Peony IX, who was a childhood neighbor in Keterburg and is one of the few people who can genuinely unsettle Jade’s calm composure. It was likely Peony's influence that helped convince Jade to abandon his dangerous fomicry research. In contrast, his relationship with Dist is tragic; they were once friends and collaborators driven by the same grief, but Jade’s decision to stop trying to resurrect Nebilim turned Dist into a bitter enemy who seeks to force Jade to return to his old path. He forms a critical bond with Luke fon Fabre, as Luke is a replica himself. Jade becomes a mentor figure of sorts, using his intellect to guide the party, and it is through watching Luke’s struggle with his own identity that Jade gains a more personal understanding of sin, consequence, and humanity.

In the story, Jade acts as the party's strategist and primary source of exposition, often providing logical explanations for the world's complex fonon mechanics and political conflicts. Though a colonel, he wields his spear in combat, a weapon he can summon and dismiss at will. He is a powerful fonic arte user, commanding the first six elements, but his abilities are initially sealed by an enemy, forcing him to regain his strength over the course of the adventure. This gameplay mechanic reflects his character arc of regaining control over his own immense power. A notable ability is his "Fonic Sight," a self-performed procedure that opened the fon slots in his eyes to amplify his power but also turned his irises red. He is forced to wear specialized glasses to regulate this power, jokingly warning that without them he might accidentally kill everyone around him.