When writing a research paper about how a character changes, your main reference will be the play itself. You will need to trace the development of Macbeth’s character throughout the play.
First, you should get a copy of the play that you can write on. Use a pencil, post-it notes, and highlighters. Color code different behaviors as you see them. When is he submissive, reflective, violent, arrogant, frustrated, afraid, repentant, and so on. How do others describe him? As you read the play again, pay special attention to Macbeth’s behavior and what it says about him.
You will notice that Macbeth follows an arc throughout the play. In the beginning he is described as a war hero.
For brave Macbeth—well he deserves that name—
Disdaining fortune, with his brandish'd steel,
Which smoked with bloody execution,(20)
Like valor's minion carved out his passage
Till he faced the slave… (Act 1, Scene 2)
Consider what the sergeant and others say about Macbeth before we meet him. They paint a picture of an honorable solider. Was Macbeth gallant and trustworthy? He is described as such.
When Macbeth meets the witches, he seems skeptical at first. Even when the first prophecy seems to come true, he is doubtful.
The Thane of Cawdor lives. Why do you dress me
In borrow'd robes?(115) (Act 1, Scene 3)
The next thing we know, Macbeth is angry that he was not named Duncan's successor, even though he had no reason to expect it.
If you read carefully, you can continue to trace this development from loyal soldier to bloody tyrant.