Amethio operates as an admin in the Explorers, driven by objectives linked to his family heritage. He is Gibeon's grandson and Cervantes's son. His mother died in a childhood car accident; afterward, Gibeon's butler, Hamber, raised him at the family mansion. Hamber became a key familial figure and personally trained Amethio, preparing him to become the first admin recruited into the Explorers.

He possesses purple eyes and black hair with silver streaks, traits inherited from his mother and grandfather. He typically sports dark attire accented by purple: a dark purple sweatshirt with a left-side stripe, black pants featuring a right-side purple stripe, black gloves, dark purple shoes, and a polo tie secured with a dark purple triangular gem.

Personality-wise, Amethio maintains a calm and collected exterior but exhibits underlying ruthlessness and manipulativeness in achieving his goals. He intensely dislikes having his accomplishments disregarded and will defy orders to prove his capability. Despite his cold demeanor, he displays occasional kindness, reassuring subordinates Zirc and Onia after failures or tending to his partner Pokémon, Ceruledge, though he usually hides such affections. He relishes Pokémon battles, showing eagerness in confrontations—especially against Friede—and resents being underestimated.

His initial mission targets retrieving a mysterious pendant from Liko, believing it vital to his grandfather's plans. He confronts her at Indigo Academy, sparking a pursuit when she escapes. This leads to repeated aerial and physical chases involving Friede and the Rising Volt Tacklers. He captures Liko's Sprigatito as leverage but later returns it following a failed negotiation. After witnessing the pendant release a black Rayquaza from Roy's ancient Poké Ball, Gibeon removes him from the pendant mission, assigning it to Spinel. Amethio then shifts focus to pursuing Rayquaza.

Following a decisive loss to Friede at Diana's castle, partly due to Terastallization, Amethio seeks training from Hamber to grow stronger. Hamber provides him with a Tera Orb after a battle where Dusknoir's Terastallization secured victory. During a later encounter with Rayquaza, Amethio intervenes to protect Terapagos from a Draco Meteor and reluctantly teams up with Friede against the Legendary Pokémon. Though defeated, this marks a temporary alliance. He later informs Liko their cooperation was situational, reaffirming Rayquaza as his target.

At Glaseado Mountain, Spinel frames Amethio during a mission, trapping him and Liko in a cave. While awaiting rescue, Amethio reveals his motivation: fulfilling his grandfather's ambitions, particularly locating "Laqua," a goal his father failed to achieve. He expresses a desire for Gibeon's approval, contrasting with his father's perceived failure. This campfire conversation occurs with Ceruledge providing warmth, mirroring Floragato's actions for Liko. Liko questions why their groups cannot collaborate, but Amethio insists their paths differ. After escaping, he warns Liko about Spinel's tactics before departing.

Upon returning to the Explorers, Gibeon, presented with fabricated evidence of Amethio's cooperation with Liko, publicly denounces and exiles him, comparing him unfavorably to his exiled father. This rejection leaves Amethio visibly frustrated. Despite declaring he would work alone afterward, Zirc and Onia demonstrate loyalty by accompanying him. He approaches his father, Cervantes, seeking information about Laquium but is coldly refused. Subsequently, with Zirc and Onia, he infiltrates the Exceed building to investigate Spinel's schemes, resulting in their capture. Hamber rescues them and reveals critical backstory: Gibeon's century-long survival using Laquium, his fractured past with Lucius, and Liko's ancestry as Lucius's descendant. Amethio deduces Spinel aims to seize Laquium for himself and resolves to thwart him, departing with his team.