It becomes clear that fate ends up ruling over the world of Oedipus Rex. Initially, Oedipus believes it is the other way around. At the exposition of the drama, Oedipus believes in his own power to rid the people of Thebes from the plague that envelops them and their city. Oedipus's strength as a ruler lies in how he asserts his own free will in solving the issues that challenge his city. He does not shirk away from his responsibility. He is a man of action. The world of inaction is something that Oedipus fails to acknowledge: "Would you have me stand still, hold my peace, and let this man win everything, through my inaction?" Oedipus associated human identity with the need to take action and the absolute condition in which individuals are able to be active agents in their own destinies and narratives. When Oedipus regards the Oracle as "empty words," it reveals much in how Oedipus views reality and being in the world.
I think that Oedipus's most painful lesson is learning that the power of fate is that it is all encompassing and rules over his being in the world. Consider the paradigm shift that this involves. Oedipus must make the move from seeing himself as the ultimate agent of action to acknowledging a force larger than human autonomy which plays a determinant role in what identity is and how consciousness is lived. Oedipus learns through the reversal brought about by his tragic condition elements larger that human will rule consciousness. It is in this where he learns that fate rules over his world and thus exercises its forceful nature in a savage cruelty. Oedipus's final plea for his children represents how much of a lesson has been learned as to the power of fate:
Consent, noble one, and touch me with your hand.
Oh, children, if you could understand, I would
give you so much advice; as it is, just pray
with me that you obtain a better life
than did the father who sired you.
The fact that Oedipus begs his children to "pray" that they have a better life than he did is representative of how much fate rules over his world. Fate has exercised such power that the once active agent seeks only the solace offered from prayer. This revelation is confirmed with the final lines of the Chorus, who suggest that life can only be deemed successful at the end when one can acknowledge an absence of "grievous" suffering. It is in this affirmation of fate and a negation of free will where it becomes clear that the former rules the world of Oedipus Rex.
There is the dominance of fate that's why he is only known that he will kill his father and marry. But he is not told about his actual parents or actual story. If he had been told,the bad consequence or tragedy would have been avoided. He performs all things on free wills of fate that leads him to his catastrophe.