A boy who grows up never knowing that his real parents are Pilar Ternera and José Arcadio (II), Arcadio is put in charge of Macondo by Colonel Aureliano Buendía… and promptly begins to abuse his power until he is shot by a firing squad.
This guy is almost a walking cliché. Ever hear that old chestnut about how all power corrupts, but absolute power corrupts absolutely? Well that, in a nutshell, is what happens to Arcadio. He has kind of a miserable childhood, since he's raised by Úrsula but never really knows who his parents are and doesn't get all that much attention from anyone except one of the native servants living in the house. Add to that a touchy, thin-skinned personality and you've got yourself someone who stores up his rage at being a victim then releases it as soon as he gets into a position of power.
So that's what he's like as a person. But what's his function in the structure of the novel? Shmoop has an idea we'd like to share with you: Arcadio is a second-generation revolutionary, following in the footsteps of his uncle, Colonel Aureliano Buendía.
What is the second generation of a revolution usually like? Let's turn to history for a little context. There's a fun stock phrase from nineteenth-century German playwright Georg Büchner: "Revolutions devour their children." What that means is that the people who start revolts (the revolution's "children") usually become its victims. Second-generation rebels become more and more radical and start to see the original rebels as too weak and middle-of-the-road.
Take, for example, eighteenth-century France, where the revolution that was meant just to overthrow the king didn't stop there. More and more of the revolutionaries were thrown under the bus by their fellow revolutionaries, until Napoleon came along and seized control with a dictatorship.
So, too, in Arcadio's case. He is Colonel Aureliano taken to an extreme: more vicious, colder, and totally uncompromising. Under his rule, Macondo is run by a bunch of teenage thugs who have all lost sight of the revolution's actual goals and now are just fixated on abusing their power over the townspeople.