The theme that most evokes the feeling of pathos, meaning pity or suffering is the theme of pride. Oedipus's excessive and wrongful pride is what creates his blindness and leads him most to his tragic downfall.
The first evidence of Oedipus's excessive pride can be seen in how quickly he assumes that Creon is involved in a conspiracy to assassinate Oedipus and take the crown. We first see Oedipus's suspicions when Creon informs him that King Laius was killed by bandits and Oedipus immediately begins believing that bandits would not have been so bold as to kill a king unless they were paid to do so by conspirators in Thebes, as we see in his lines, "How did a bandit come to dare so much, unless he acted with money from here?" (135-136). Oedipus further suspects a conspiracy to not just overthrow the late King Laius, but himself as well when Tiresias refuses to tell him who murdered Laius, as we in his line, "Know that I think you, too, had your hand in this deed and did it" (365-366). Finally, when Tiresias does reveal to Oedipus that soon he will realize that he was the slayer of Laius, his own father, Oedipus immediately believes that Tiresias has been paid by Creon to deliver false prophecies and believes that Creon is plotting to overthrow him.
However, as Tiresias points out, Oedipus's excessive pride has created a blindness within him. We see Tiresias pointing out Oedipus's blindness when he asserts that he does not see what he has done nor whom he is living with, as we see in Tiresias's lines:
You, even though you see clearly, do not see the scope of your evil, nor where you live, nor with whom you dwell? Do you know your true descent? And secretly you are an enemy to your own kin. (433-437)
Instead of being able to clearly see the murder he committed and with whom he is living with, even though he was given a prophecy informing him that he would kill his own father and sleep with his own mother, he has let his pride over being ruler of Thebes influence his perception of reality. Hence, it is ultimately Oedipus's pride that leads to his downfall, creating the pathos found in the play.