In what ways is Oedipus a good King? In what ways is he a good person? How do these virtues result in negative consequences for Oedipus?
Oedipus, the protagonist of Oedipus the King (also known as Oedipus Rex), is a tragic hero. A tragic hero is typically someone in a position of power, like a king of ruler. The tragic hero has some admirable qualities but is not perfect; the audience must relate to him in some way in order to invest in his story. The hero also has a tragic flaw that ultimately leads to his demise.
Early in the play, Oedipus is a mostly positive figure. He became King of Thebes by solving the riddle of the Sphinx, who had been torturing the people of the city and not allowing anyone in or out of Thebes if they could not answer the riddle. Because he saved them from the Sphinx, the people of Thebes respect Oedipus and trust him as their leader. Oedipus the King opens with a scene in which Oedipus emerges from his palace to find a group of citizens praying with a priest. He learns that they are asking for help—from Oedipus and from the gods—to end a plague that has resulted in famine and infertility across the city. The people here demonstrate their trust in Oedipus; they believe he will listen and that he is disposed to help them. Proving them correct, Oedipus has already sent Creon to the Oracle to find an answer to the plague. This also shows that he is a proactive king who wants to protect his city and help it to thrive. Oedipus further shows his dedication to his people when he vows to find and punish the killer of Laius, who is the cause of the pestilence.
Once Oedipus begins to investigate the crime, however, Oedipus's negative traits begin to show. He swiftly becomes angry with the prophet Teiresias, and we also later learn that his quick temper is what led him to kill Laius and his entire traveling party. He is also stubborn and paranoid, as demonstrated by his obstinate insistence that Teiresias reveal information that the prophet promises Oedipus will be of no benefit to him and by his conviction that Creon and Teiresias are conspiring against him. At this point in the play, Oedipus begins to shift from king to tyrant, and his flaws eventually lead to his downfall. He is revealed to be Laius's killer and blinds and banishes himself.
Oedipus is a good king, in part, because he seems to anticipate the needs and desires of his people. Even before the priest comes to beg him for help, Oedipus has already deployed his brother-in-law (and uncle, unbeknownst to him), Creon, to go to the oracle and ask for information about how to free Thebes from its suffering. Had he not done this, he never would have learned that the reason for the suffering was that the previous king's murderer had never been found, and thus the search for this murderer would not have begun in earnest. Without the investigation, Oedipus would not have been revealed as the murderer, and, as a result, no one would know that he is Laius's son. He actually married and had children with his own mother.
Good or bad, Oedipus does want to know the truth. Even though his journey for the truth begins to be influenced by his pride, rather than just a simple desire to help his people, it did—at least—begin with an honest hope. He thinks it is terrible that there never was a full investigation into Laius's murder, and he wishes to know what really happened for his sake and for the sake of Thebes. Then, he offers to only exile the murderer, rather than execute him, a decision that shows mercy. However, in the end, it is possible Oedipus would rather be dead than exiled. He may regret his mercy.
First, Oedipus is not a king (a hereditary monarch whose power derives from traditional sources of legitimacy) during most of the play, but a "tyrant", a monarch appointed by the will of the people. He only discovers, ironically, that he is the legitimate king at the end of the play when he loses power.
He arrives as a benefactor to the city, having solved the riddle of the Sphinx. He is determined, at whatever the cost, to find the cause of the ritual pollution that is harming the city. He consults with the people of the city and tries to help them.
His attempt to find the source of pollution reveals that he is that source -- but the curse under which he operates is the will of the gods, and cannot be escaped. That he is a fundamentally good character (albeit flawed) is what makes this a tragedy -- the misfortunes of a bad person are deserved, and thus don't evoke pity.