Principal Abacus Cinch as Sergeant-Major Duncan, the captain of Destro's personal guard and senior ranking officer of the Iron Grenadiers, from the G.I. Joe Marvel comics.

I had the idea of having the Crystal Prep Shadowbolts take up the role of some of the individual named Iron Grenadiers characters, and I thought Abacus Cinch was the perfect fit for the Sergeant-Major, both being there to instill high expectations and strict discipline.