In a tragic play, what is more important the character of a person or destiny (fate)?
In a tragedy, there are three important elements and if we emphasize one at the expense of the other, we will distort the basic function of the tragedy.
First, fate is important. Often there is a prophecy or something related that predicts something will happen to the person. We see this is Oedipus (marry his mother and kill his father), and Julius Caesar (death on the ides of March).
Second, the person's character is important. As Aristotle says, a tragic hero must be noble and have impressive traits.
Third, the tragic hero must make decisions. His or her freedom is intact as well as fate. There is a tension that must be maintained, even if it is hard to do so.
In short, fate, the character of the person, and freewill are all equally important.