Oedipus was a victim of his fate. He was also a victim of his own ego and rashness. In his confidence that he had outmaneuvered the Fates, he actually pushed himself into the fate he tried to escape.
One of the large themes that is present throughout the "Oedipus" trilogy is the power of fate. In ancient Greece, there was a powerful belief in the power of a predetermined fate. Oedipus was told of his fate, and he was determined to beat it. Despite the great lengths that he used to try to change his fate, the Fates proved their power over human life by demonstrating that the choices Oedipus made in an attempt to escape his fate were the very ones that sealed it.