The character known as Colonel is a military officer embedded within the Commonwealth spy network. He holds the position of an officer of coordination, sent by the army to oversee and observe the activities of the intelligence division known as Control. His official cover is as a staff member within the Commonwealth's embassy. His civilian counterparts within Control are L, the director, an analyst named 7, and a technical specialist called Dollyshop.

In terms of personality, Colonel projects an aggressive and overtly masculine demeanor, in sharp contrast to the more reserved and strategic nature of his colleague L. He has a habit of chewing on a cigar and often speaks with a seething intensity, punctuating his words by hammering his hand on the table. His worldview is firmly rooted in the belief that the military represents legitimate and direct power. Consequently, he looks down upon the subversive and clandestine methods employed by spies, viewing them as less honorable or effective compared to conventional forces. This perspective fuels a disregard for the shadowy operations of Control, as he believes that true strength is displayed on the battlefield, not through infiltration and deception.

Colonel's primary role in the narrative is as a representative of the military establishment within the Commonwealth's intelligence apparatus. He acts as a counterpoint to L, constantly advocating for the army's perspective and often clashing with the spy agency's methods. His presence injects a significant degree of political and institutional tension into the story. Despite his contempt for espionage, he is a pragmatist. When the Princess of the Kingdom proposes an alliance with the Commonwealth, he is notably one of the first members of Control's leadership to support accepting her offer, recognizing the strategic value of having an asset within the royal family. However, his primary concern in this arrangement is geopolitical; he fears that exposure of the Princess as a spy could ignite a world war, highlighting his focus on large-scale, militarized conflict rather than the smaller, deniable operations of spies.

His key relationships are primarily with the other members of Control, especially L. He represents the army's growing influence over the spy network. This power struggle comes to a head when Control is briefly taken over by a revolutionary military faction. During this coup, Colonel is unexpectedly transferred from his position, suggesting that he was a moderate who was sidelined by more radical army elements. In a significant turn of events, the army orchestrated a failed assassination plot against the Queen of Albion. After this plan collapses, the military faction falls from grace, and Colonel is reinstated to his former position within Control, implying that his more pragmatic approach was favored once the radicals were discredited.

Colonel undergoes a notable development from a hostile outsider to a reinstated authority figure. Initially seen as a disruptive overseer dismissive of espionage, he is removed during an internal power struggle. His return indicates that while the conflict between military bravado and intelligence subtlety persists, his specific role as an army liaison remains necessary for the Commonwealth's operations. He does not possess unique spy skills or special abilities like the field agents. Instead, his significance and power derive from his formal rank and his role as a conduit for the army's resources and political will. He is a decision-maker, not an operative, whose notable ability is his influence over the allocation of military support and his authority to challenge Control's civilian leadership.