He is often the voice of reason to Johnny's insanity but winds up getting manipulated into supporting Johnny's crazy schemes and adventures (usually because of steak or Johnny tempting him into it). Despite his devotion to Johnny, Dukey frequently expresses deep disdain towards Johnny's less intelligent antics, believing their situation as master and pet are reversed.
His dog habits greatly annoy Johnny's sisters, to which Johnny takes deep delight in. Usually once per episode, when trouble arises and there's no alternative, Dukey will say something along the lines of "Here's an idea: RUN!" Similar to Johnny's "Johnny X" form, Dukey also has a secret identity which unlike his master he does not particularly enjoy called "Super Pooch", although he is also referred to as "Super Dukey" and "X-Pooch". When in the "Super Pooch" form, Dukey can fly and in the Third Season has shapeshifting powers, the ability to sense what others are doing, and the ability to teleport. He has the power to fly as a sidekick (to Johnny) but usually crashes when landing. He also likes to drink hot coffee. His favorite food is steak (He likes all kinds of steak, but his favorite is porterhouse seen when Dukey quizzes Johnny and his cyborg clone to see who's the real Johnny.