Joe Team, Leatherneck served as a corporal in Gitmo, then as a tech sergeant in the 1st Recon Bn in Vietnam, then a drill instructor on Parris Island, and then a gunny at Camp Lejeune.

[1] As a drill instructor, Leatherneck assumes the role of an enemy when training Joes, turning himself into an insurmountable obstacle.

Leatherneck is ill tempered, obnoxious, and holds irrational grudges against those who don't fit his definition of "worthy".

Their rivalry stems from the tradition of competition between the Navy and the Marine Corps, but their constant bickering conceals a shared respect.

[8] In the episode "The Rotten Egg", it is shown in flashbacks that Leatherneck worked at the CEC Military Academy, where he had problems with a tough cadet named Buck McCann.

For instance, when the drill instructor witnessed him injuring a fellow cadet with sadistic glee, Leatherneck immediately punished him by giving him 50 laps around the parade ground and withdrawing his recommendation for him for officer candidate school.

Leatherneck is trapped following a hunt on him (where he was knocked out by Sheila despite rescuing her from a river) and Buck leads the cadets to attack the Parris Island Military Academy.

[9] In "My Favorite Things", Leatherneck is among the Joes participating in a battle at a Dutch museum, where he stops Serpentor from stealing an ax, half of which he keeps as a trophy.

Leatherneck later saves a captured Wet-Suit at Vlad Dracula's castle, but is stabbed by a poison dart from Serpentor.

The Joes, Dreadnoks and LaCarre eventually put aside their differences and hook the antimatter pod to the helicarrier's rotors, rising them out of the water.

While the Joes and LaCarre recover from decompression sickness in a chamber, Leatherneck and Wet-Suit argue over a game of cards.

As he imagined the characters in his head, he described four of the Joes on front lines of the battle: Hawk, Leatherneck, Wet Suit, and Sci-Fi "stood in procession, weapons raised, adrenaline pumping feverishly.