Leo

Leo is curious, energetic and brave enough to investigate supernatural dangers alongside Jean. Their Akuma Patrol reflects both childhood enthusiasm and a genuine desire to protect people.

He is also deeply attached to his mother. When confronted with overwhelming grief, the warnings he knows about the Millennium Earl become harder to follow than they seemed while the danger was theoretical.

Leo is an ordinary human child and possesses no Innocence or supernatural combat abilities.

His knowledge of Akuma comes from investigating them with Jean. That information allows him to understand some of the Earl's methods but offers no physical protection against them.

Leo and Jean establish an Akuma Patrol and investigate reports of suspicious people in their neighborhood. Their activities eventually intersect with Allen Walker, who recognizes that the boys have stumbled into genuine danger.

After Leo's mother dies, the Millennium Earl approaches him with the same offer he uses to exploit other bereaved people. Despite knowing what Akuma are, Leo calls his mother's soul back. The resulting Akuma kills him and uses his body as its disguise.

The incident forces Jean to confront the reality behind the game-like patrol he and Leo created and gives Allen another painful example of the Earl's ability to weaponize grief.

Jean is Leo's best friend and partner in the Akuma Patrol. Jean later has to confront the Akuma created from Leo's mother after it takes Leo's appearance.

Leo's mother is the person whose loss overwhelms the caution he had learned from investigating Akuma. His attempt to restore her allows the Millennium Earl to turn her soul into an Akuma.

The Millennium Earl exploits Leo's grief and persuades him to call his mother back from the dead.

Allen Walker becomes involved with the boys' investigation and recognizes the Akuma threat they have discovered.