I think that the contrast between Proctor and Parris can be seen as the embodiment of protagonist and antagonist. Proctor is the protagonist of the drama. The evolution and change he undergoes make him the central figure in the plot. As Proctor becomes more actively involved in the opposition to the trials, he becomes the central figure in the drama. At the same time, as the trials increase in intensity, Parris becomes the strongest proponent of the trials. In Act III, Parris' insistence on Proctor being found guilty is matched by Proctor's determination that the trials, and those who support the trials, are fraudulent. In this dynamic, I think that Proctor becomes the protagonist and Parris the antagonist. This is seen even more in the final act of the play, where Parris is fearful for both his credibility and his life, while Proctor, for the most part, is confirmed in his ability to stand for his name. Even during his momentary lapse in his "confession," Proctor is standing quite powerful as the protagonist, the central figure, in representing transcendent values in a time of contingency.