Kapi performs as an anthropomorphic dog in Vitalis's traveling troupe, capable of human speech unlike his original canine counterpart. He exhibits an exuberant, comedic personality through loud, lovable, and occasionally foolish behavior, delivering comic relief via background antics or foreground actions like dancing upright or stealing Vitalis's backscratcher.

He shares a deep bond with protagonist Remi, acting as a loyal, protective younger brother figure. This devotion drives Kapi to support Remi after Vitalis's arrest and aid in reuniting him with his biological mother, Mrs. Milligan.

A narrative addition introduces Kapi's romantic pursuit of a purple female cocker spaniel—exclusive to this adaptation—who wears a pink bow. Their subplot features moments like a "Dance of Romance" where Kapi, engrossed in performance, steps off a ship, hovers mid-air via cartoon physics, and falls into water.

As a "Consenting Animal Performer" in Vitalis's troupe, Kapi actively seeks fame and relishes entertaining audiences, reflecting adaptation choices emphasizing anthropomorphic entertainment. Promotional materials inconsistently spell his name as "Kapi," though it derives from the Italian "capitano" meaning "head."