Were the gods fair to Oedipus?
It's tough to characterize a prophecy which states that one will kill one's father and marry one's mother as "fair," but Oedipus's incredible pride in thinking that he could outwit the prophecy qualifies him, certainly for the ancient Greeks, for some divine retribution. The prophecy came from the oracle of Delphi, the mouthpiece of the god Apollo. Regardless, Oedipus believes that he can avoid this fate by simply refusing to return home; this way, in his mind, he cannot somehow accidentally kill his father, Polybus, and marry his mother, Merope. The problem? These aren't his biological parents; they are his adoptive parents. In attempting to avoid his fate, he actually does the thing that enables it to come true: he moves to Thebes. He makes critical errors as a result of pride, and things never work out well for a mortal who believes that they can outwit the gods, or that their will could be more powerful than a god's will. Is it fair? To me, not particularly: Oedipus is proud, to be sure, but he isn't evil. However, such a story would have taught its original audience a key lesson about the crucial importance of humility and respect for the gods.