The Question and Answer section for Oedipus Rex or Oedipus the King is a great resource to ask questions, find answers, and discuss the novel.
If you consider that the Gods are all powerful, it is the fault of Oedipus to challenge his fate. Oedipus, however, remains a sympathetic character because he dares to declare his own freedom from the bondage of his fate.
The seer's name is Teiresias. Teiresias and old man, who is blind.
In the first speech, we lean that Thebes is under a curse. The curse has destroyed their crops, made their women sterile (unable to bear children), and that people are sick and starving.