There is a very close relationship between plot and characterization or character development. As the plot moves forward, the plot reveals the characters' qualities. Likewise, it is also the characters' actions, beliefs, attitudes, and motivations, all of which make up characterization, that help to move the plot forward.
One of Oedipus's qualities is his excessive pride and it is that quality which drives the plot forward the most. His excessive pride is especially seen when he refuses to believe the truth of the oracle that Creon reports, believing instead that Creon is involved in a conspiracy to overthrow him and take the crown. We first see Oedipus reach the conclusion that there is a treasonous plot afoot in Thebes when he learns from Creon that the late King Laius was killed by bandits. Oedipus can't believe that bandits would dare attack a king unless they were bribed to do so by a Theban as part of a plot to take the thrown, as we see in Oedipus's lines, "How did a bandit come to dare so much, unless he acted with money from here?" (135-136). Instead, he begins to accuse both Creon and Tiresias of being involved in the plot to, not only assassinate Laius, but himself as well.
As Tiresias points out, it is Oedipus's excessive pride that leads to his blindness, preventing him from being able to see the truth of both Tiresias's prophecy and even the one Oedipus was given by the oracle at Delphi when he was a younger man. When he was a young man, Oedipus went to the oracle to find out who his true parents were but was only told that he would one day murder his own father and sleep with his own mother, just as Tiresias is presently warning him. It was his pride and his temper that drove him to kill a man at the crossroads of Delphi, who turned out to be his own father, just as his pride is prohibiting him from seeing the truth of his own actions, as Tiresias argues in the lines, "You, even though you see clearly, do not see the scope of your evil" (433-434).
However, as the plot continues, Oedipus begins to realize more and more things about himself. Both his blindness and his pride are lifted, leaving him a cursed and agonized man. Hence, we see that it is Oedipus's characterization as being prideful and blind that helps to drive the plot forward; likewise, Oedipus's pride and blindness are revealed in the progress of the plot.