The strip's premise, all its 14 or so years, is utterly simple. Mallard Fillmore is a cynical talking duck in an otherwise all-human world, a la Marvel's onetime Howard the Duck. D.C. Every day, he spurts a two-line rant against whatever Those Liberals are doing these days. Mallard Fillmore has none of these. There are no storylines and no character development.
Mallard has no apparent family or personal life.
Despite the lack of any narrative element, the strip still imbues its title character with a personality. And it's perhaps the most unattractive personality of any daily-comics protagonist ever. But despite his personal identification with the political causes of America's power elite, he can't stop seeing himself as a disempowered victim of Those Bad Old P.C. Liberals. Pecadillos and hypocrisies among Democratic politicians are skewered regularly in the duck's mini-rants. The same misdeeds, when performed by Republican politicians, are never mentioned.