Jean Jacques, operating under the alias Tarantula, functions as a professional assassin initially contracted by Count George de Germont. His past unveils a critical familial tie to Randy Cortot (alias Lundi), later confirmed as Randy's estranged older brother—a relationship defined by a Cain and Abel dynamic fueled by their conflicting loyalties.

As Germont’s enforcer, Tarantula executes missions against protagonists Randy and Jeudi, cementing his role as a recurring antagonist. A decisive rupture occurs when Germont commands him to assassinate Swiss General Henri Guisan. Tarantula refuses, declaring, "the Germont I knew has just died to me right now," and abandons his assignment—marking both a moral boundary and a fracture in his allegiance.

This break triggers Tarantula’s redemption arc, transitioning him from antagonist to ally. He joins Randy, Jeudi, and their resistance cell in opposing Germont and Nazi-linked forces. His evolution culminates in attending Randy and Jeudi’s October 1945 postwar wedding, signaling reconciliation with his brother and acceptance into their community.