What role did the messenger play in oedipus’ life?

The Messenger from Corinth arrives to tell Oedipus that his father, Polybus, is dead, and that the people of Corinth wish Oedipus to be their new king. He also reveals to Oedipus, however, that Polybus and Meropé are not his real parents. He says that long ago a stranger from Thebes gave him a baby as a gift to the king and queen of Corinth. This baby was, of course, Oedipus who would grow up to be king himself. The Messenger, then, provides the audience with the first real clue of dramatic irony that suggests that Teiresias' words (and those of the Oracle) are true - long before Oedipus discovers their veracity.