Oedipus does not know about this prophecy or that Laius was his father. Once the citizens call upon Oedipus to kill the man who killed Laius, the readers already know that Oedipus must die. Although tragic irony is a form of dramatic irony, it is important to emphasize that what happens in this story is tragic irony. Dramatic irony simply says that the audience knows something that a character does not. However, "Oedipus Rex" is a tragedy. Therefore, the audience must have prior knowledge to a tragic event. .
Many people, including Socrates, will say that in order to have a tragedy, one must have fate. Fate is not an easily explained idea. Perhaps the best way to explain the idea of fate is to describe it as a principle which is believed to predetermine events. I find it easier to think of Fate as a character in this play. If Oedipus is the protagonist, Fate can be seen as the antagonist. Fate is Oedipus biggest enemy. It will mean the destruction of Oedipus, the murder of his father, and the suicide of his mother. When Oedipus was first born, and his parents heard the horrible prophecy, they sent Oedipus high into the mountains. They wanted to rid their family of the future they were given. Perhaps his parents should have thought more clearly about fate. Since it controls predetermined events, there was nothing they could do to stop this prophecy from becoming reality. Eventually, a man found Oedipus and raised him as his own. Oedipus eventually killed his father, Laius, and married his mother, Jocasta. As Sophocles said, "men are helpless so far as their fate is concerned- .
Fate and character are intertwined in this story. There are certain characteristics that can feed bad fate. For example, Oedipus was a very proud man and very impulsive. As soon as Creon returned from Olympus with the message that Oedipus must kill the man who killed Laius, Oedipus goes into a long speech. He explains that he will do anything to find this man and kill him.