Rob Lucci emerges as the central antagonist in the "Episode of Merry" special, which condenses the Water 7 and Enies Lobby sagas. His history marks him as a supremely trained assassin and the most powerful operative ever in CP9, the World Government's covert intelligence unit. At just 13 years old, he demonstrated his ruthless creed—"weakness is a sin"—by slaughtering 500 soldiers and hostages during a crisis.

For five years, Lucci infiltrated Water 7, posing as a reserved and courteous shipwright at Galley-La Company's Dock 1. He maintained this cover by communicating almost exclusively through his pet pigeon, Hattori, using ventriloquism. This facade masked his true, psychopathic nature: a cold individual governed by the philosophy of "Dark Justice" (闇の正義, Yami no Seigi), which justifies limitless violence to eliminate threats to the World Government. His mission included secretly locating blueprints for the ancient weapon Pluton.

Lucci wields exceptional combat prowess, mastering the Rokushiki martial arts and the devastating Rokuougan technique. His abilities are further augmented by the Neko Neko no Mi, Model: Leopard Devil Fruit (ネコネコの実 モデル:豹), allowing transformation into a leopard or hybrid form for enhanced speed and strength.

During the Enies Lobby incident recreated in "Episode of Merry," Lucci abandons his shipwright persona to lead CP9's hunt for Nico Robin. He savors combat, deliberately prolonging his brutal fight against Monkey D. Luffy despite mission imperatives, revealing his sadistic nature. His defeat by Luffy leads to dismissal from CP9 by Spandam.

Following the timeskip, Lucci resurfaces as a high-ranking agent within CP0, the World Government's elite intelligence unit. Now clad in a mask and white-and-blue suit, his position signifies reinstatement and grants authority over former superiors like Spandam. In "Episode of Merry," his role aligns with the original Enies Lobby arc, though the special streamlines his battles to focus on key confrontations.