John Proctor is dynamic because of the conflicts he faces. He does not change over the course of the play so much as he overcomes significant challenges.
Proctor faces a twin conflict in the play. He is beset by an internal struggle to reclaim some measure of self-regard but finds himself forced to admit publicly to a shameful affair with his former servant, Abigail Williams.
This struggle is well articulated and carries high stakes. It is also complicated. Acting honorably in court will mean that Proctor has to admit to acting dishonorably in having an affair. If he keeps his secret, he will be acting cowardly.
This dynamic is compelling and in its repetition becomes the mark of Proctor's dynamic nature as a character. He overcomes his challenge once then faces it again when he is imprisoned and faces his own death.
Proctor's final challenge is, again, to find a way to recover his honor and self-regard. To do so, ultimately, he must accept a death sentence. Choosing to die instead of sign a false confession, Proctor achieves his goal and re-captures his honor. The fact of his success is underscored by the profound and emotional nature of his challenges.
Faced with a choice between life and honor, Proctor chooses honor. This decision in itself is interesting. Given the context of the play the decision becomes truly captivating.
A farmer; stern; harsh-tongued man; hates hypocrisy; had an affair with Abigail; novel's tragic hero; honest; proud man; cares about his reputation and the welfare of his family; guilty; fear of public opinions; has personal integrity; religious