Character Role Analysis
Those pigs are pretty antagonizing, but especially Snowball and Napoleon. They start off as proles under human control but quickly ooze into leadership after the Rebellion. Then the antagonism beings: stealing food, abusing the animals, and ultimately becoming indistinguishable from the oppressive humans they once fought to overthrow.
In general, power corrupts the pigs; they don't start off as antagonists (think Old Major—not a dislikable dude!), but rather become antagonists as the story develops. Well, maybe not Napoleon. We think he might have been bad from the beginning.