As a character, Argaven serves as a foil for many characters, most notably Ai and Estraven. Estraven wants the Ekumen to come because he believes they will change Gethen for the better. Ai wants the Ekumen to come because the exchanging of ideas and technology will help both the Ekumen and the Gethenians. Both may fear the unknown future, but they move toward their goals all the same.
Argaven wants nothing to do with change. He fears it, and his fear rules him much like he rules his nation—with a little touch of the crazy. As he says himself, "I fear those who sent you. I fear lairs, and I fear tricksters, and worst I fear the bitter truth. And so I rule my country well. Because only fear rules men" (3.69). Argaven fears for his country, for his future, and that fear blinds him to the possibilities presented by the Ekumen.
When Ai next meets Argaven at the novel's conclusion, the King has lost his heir in childbirth. The King now looks like "a woman who has lost her baby, like a man who has lost his son" (20.31). Argaven states he no longer fears Ai, and though it is left ambiguous, it seems the lost of his child, of his future, has given the King nothing left to fear.
But Argaven only agrees to the Ekumen treaty so he can put "Karhide first!" (20.63). While he might have put his fear aside by the novel's end, Argaven still serves as a foil for Estraven and Ai. Our heroes did what they did to serve mankind as a whole (20.54). Even in the end, Argaven only serves the interests of Karhide. As Estraven says of Argaven, "[…] he's a king, and does not see things rationally, but as a king" (1.70).
We're left wondering here if Argaven's true purpose in the novel is to serve as a critique of monarchy. Is the problem that he's fearful and possibly mad? Or is it that he's a king—and kings are too tied to their own country and their own past to be able to rule in a world that is becoming global? Is there a place for monarchy in the governments of the future?