Oedipus is the main character of Oedipus Rex by Sophocles. At the beginning of the play, the Priest states:
So now, you best of men, raise up our state.
Act to consolidate your fame, for now,
thanks to your eagerness in earlier days,
the city celebrates you as its saviour.
Thus the role of Oedipus is to continue to use the power he has obtained through saving Thebes from the Sphinx to preserve Thebes from the plague. The action of the play revolves around the quest of Oedipus to discover the identity of the murder of Laius who has brought the wrath of the gods down upon the city. The main tragic action is the discovery of the identity of the murderer.
Teiresias is a prophet who foretells the truth by his divine gifts that Oedipus seeks. In a sense, he is also the figure that enables us to condemn Oedipus as impious. In many ways, one can argue that Oedipus consistently acts in a responsible fashion for the best of the city (according to the imperfect information he possesses); in his arrogant treatment of Teiresias, we see his own lack of reverence for the gods, justifying his downfall.