Duncan is an ambitious monster who desires to be the head of MIFT. Much like Randall Boggs, he is not above using underhanded or conniving tactics to achieve his goal. Unlike Randall, Duncan has redeeming traits and morals and actually gets along with his co-workers most of the time.
Duncan is an olive green monster with four eyes. Strangely, Duncan's eyestalks are all different sizes in height. Duncan has multiple characteristics of a dragon such as webbed wings, long, skinny fingers which resemble claws, and dragon-like feet, but has a different body shape than a dragon.
He used to have a pencil mustache, as seen in "The Vending Machine". He likely shaved it sometime after his employment photo.