What is a good thesis question for Oedipus the king and a burial at Thebes...I'm writing a critical paper but don't know

There are lots of different ways you could go with this
but one thing you might try is something about fate.  Fate was very important to the
ancient Greeks.  They believed that a person's destiny was written in stone.  If a human
being tried to deny and defy his fate, as Oedipus does, a greater tragedy would ensue. 
When a mere mortal tried to write his own fate, he's elevating himself to the level of
the gods.  This is an example of hubris and won't be tolerated by the Olympians.  Maybe
your thesis question coud be: "What is the role and importance of fate in Oedipus Rex
and Burial at Thebes?"