How does Macbeth's character change from Act 1, Scene 3 to Act 3, Scene 1?

If we compare Macbeth in these two scenes, what we find is that his character has undergone significant change. Specifically, he has lost his friendly feeling toward Banquo and developed a strong sense of paranoia.

In act I, scene III, Macbeth and Banquo are returning together from battle. We know that there is a strong feeling of friendship between them. Banquo calls Macbeth "good sir" and "worthy Macbeth," for instance. Together, they try to better understand the strange prophecies which the witches have delivered to them.

If we compare this to act III, scene I, the change in Macbeth is clear. Gone is that friendly feeling toward Banquo, replaced by an all-consuming sense of paranoia. Macbeth is terrified that he will be replaced as king by Banquo's son:

To be thus is nothing,

But to be safely thus. Our fears in Banquo

Stick deep.

When Macbeth talks about the "rancor" in his peace, he is alluding to the paranoia that he now feels toward Banquo. This leads him to hire two men to kill Banquo and Fleance—a sign that their bond is forever broken and that Macbeth is becoming an increasingly paranoid and tyrannical leader.

How does Macbeth's character change from Act 1, Scene 3 to Act 3, Scene 1?

The first thing worth thinking about is whether Macbeth, over the course of William Shakespeare's play Macbeth, actually does change character, or whether the monstrous character that is gradually revealed is one he possessed all along and which gradually becomes more apparent to us over the course of the play.

The key event in the play that begins the change is the encounter with the weird sisters on the blasted heath. In this scene, Macbeth evolves from merely be ambitious to be outstanding in service of his king to wanting to be king. We may regard this as a change in degree of ambition.

The next change is the murder of Duncan. He seems strongly influenced by Lady Macbeth in this. One can argue that once he has done the evil deed of killing Duncan, he loses all inhibitions that might have held his evil impulses in check, and not only becomes more violent but loses his capacity for self-restraint.

In Macbeth, how does Macbeth's character change across acts 2 to 5?

In Macbeth, having just murdered Duncan, Macbeth is already questioning himself, realizing that, as he says, "'twere best not know myself,"(II.ii72). However, at the beginning of Act II, scene iii, he changes quickly from the doubting, confused and possibly remorseful Macbeth, to a calculating murderer, determined to carry through the plan. His references to "a rough night," (II.iii.59) mean far more to Macbeth and to the audience than the words themselves. Having been rewarded with a title because of his valor, he is now scheming and covering his tracks by admitting to having killed Duncan's guards, suggesting that he did so out of loyalty and love for his king, when he saw that Duncan was dead. He is notably more bold and already seems less reliant on Lady Macbeth.

With his new-found confidence, Macbeth has arranged to have Banquo killed because, as he says, "Under him, my Genius is rebuked," (III,i.55) which means that Macbeth sees Banquo as a threat to Macbeth's own future as king. However, in Act III, scene iv, Macbeth learns that, although Banquo is dead, his son, Fleance escaped and he says that he feels, "Cabin'd, cribb'd confin'd," (III.iv.24). He is so affected by this news that he imagines the ghost of Banquo and it is necessary for Lady Macbeth to step in and suggest that he is having a "momentary" fit as his behavior is sure to expose what they have done otherwise. The fact that it is Lady Macbeth who calms Macbeth reveals the change in Macbeth as he, once again, relies on her steadfastness and undaunted personality to move their plan forward. His fearlessness is replaced by fear and now he feels that he also needs to meet with the witches as he is questioning his future. It is clear to the audience that he is delusional because, with Lady Macbeth's support and having made his decision to visit the witches again, Macbeth convinces himself that, "We are yet but young in deed," (143), and therefore there is a chance that this whole problem will resolve itself.   

By the time we see Macbeth in Act V, scene v, he, yet again, feels invincible because, having met with the witches, he is convinced that he cannot be beaten. Based on the apparitions which confirmed that, "None of woman born,"(IV.i.80) can defeat him until the wood "Shall come against him,"(91), Macbeth, in Act V, scene v admits that he has, "Almost forgot the taste of fears," (9), suggesting that nothing scares or alarms him. He is saddened by the news that Lady Macbeth is dead and the change here, when the messenger alerts Macbeth that the wood seems to be approaching, such as was described by the witches, is Macbeth's acknowledgement that the witches were possibly lying. As he says, he is beginning "to doubt the equivocation of the fiend," (43) the witches being representative of the "fiend." He is however, ready to die, "with harness on our back," (52), suggesting that he believes that he still has some degree of honor.  

How does Macbeth's character develop in Act 2, Scene 1, Lines 33–64?

In the edition of the play I have, line 33 in this scene is Banquo's, "So I lose none." This is a pivotal scene and moment for Macbeth. Just before the section you have indicated, the two friends discuss the "three weird sisters," and Banquo reveals that he is concerned that they may have shown "some truth" to Macbeth. Macbeth tells Banquo airily, "I think not of them," which is an example of irony as the audience knows that Macbeth has thought of little else. After their conversation, Banquo says that he will keep his "bosom franchised and allegiance clear," which is then juxtaposed with Macbeth's sinister change of tone as he begins the famous "dagger" soliloquy.

Having dismissed the servant, we witness Macbeth begin to wrestle with his conscience. This speech, in which Macbeth asks, "is this a dagger which I see before me," is our first true indication that the guilt of what he is about to do is truly beginning to affect Macbeth's mind; he is hallucinating "a dagger of the mind . . . in form so palpable" that he feels sure it must be real. Macbeth is not sure whether his "eyes are made the fools o' the other senses / Or else worth all the rest"—that is, he is unsure whether his eyes are deceiving him, or whether, in fact, the dagger with its "gouts of blood" is showing him the clearest truth.

Macbeth attempts to steady himself so as not to become too preoccupied with what the dagger means—"There's no such thing"—and yet, we see already that he is having difficulty sleeping because of the effects of the guilt on his "heat-oppressed brain," even before he has committed the planned act. "Wicked dreams" assail Macbeth. However, as the soliloquy progresses, we see a turning point in Macbeth's deliberations. "Whiles I threat," Macbeth says, "he lives." He seems to have determined that Duncan should not survive, and then, after the bell tolls, Macbeth declares, "it is done." He interprets the bell for us as "a knell / that summons thee to heaven or to hell." The couplet here symbolizes the end of the scene, but also lends a decisive end to Macbeth's wrestle with his conscience. At this point, it is clear that he is going to commit the murder of Duncan.

How has Macbeth's character changed by act 3, scene 1?

In Act III, Scene 1, Macbeth seems to have lost all conscience and succumbed to his lust for power.

Beforehand, Macbeth has faltered at the idea of killing King Duncan in order to become king more quickly and prevent Duncan's son Malcolm from having any claim to the throne. In Act I, Scene 7, in a soliloquy, Macbeth has had compunctions against committing the murder because Duncan is his kinsman and he is virtuous. Then, since he is going to be Duncan's host, Macbeth has felt he should be kind and not murder the king. Thirdly, if the king dies, the country will mourn and the news of the horrible deed will spread throughout. Nevertheless, Macbeth concludes that the only motivation he has is his "vaulting ambition which o'erleaps itself/And falls on th'other--"(1.7.27-28)

So Macbeth has killed Duncan because he has also been coaxed by Lady Macbeth to commit the murder after she questioned his manhood. After the murder, however, he is overcome with guilt as he has imagined a voice cry "Macbeth doth murder sleep" (2.2).

But, now, in Act III, Scene 1, Macbeth seems to have become more callous and ambitious. When Banquo tells him that he will be gone for two hours, but will arrive at Inverness for the banquet shortly thereafter, Macbeth hires two murderers to eliminate Banquo as well as his son Fleance. He is even so treacherous as to wish Banquo "While then, God be with you!" 

Macbeth has hired these murderers because he feels that if he does not kill Banquo, he has murdered "the gracious Duncan" only so Banquo's sons could become king. Therefore, he challenges fate and vows that he will fight it to the death.

Macbeth changes from loyal subject to king killer; how and why does the change come about and how does this change affect him?

I'm going to get a little more radical and suggest that while Macbeth may have been anoutwardly loyal subject, he had the makings of a "king-killer" pretty close to the surface from the beginning.

While the witches may have been an instigation to Macbeth's actions, no mere words could make him commit the heinous acts he committed unless there was already something that evil lurking in his heart.  The mere suggestion is not enough.  Undoubtedly he already had that ambition in him, just waiting for an opportunity to present itself.

Too often Lady Macbeth is blamed for his actions, yet it's clear he has thoughts of murder before he ever sees her to discuss the predictions in person.  Immediately after the witches disappear, Macbeth says, in an aside: "My thought, whose murder yet is but fantastical, shakes so my single state." He has barely had the prediction spoken to him and already the words "thought" and "murder" are in his mind. 

Macbeth is not averse to violence to achieve a goal.  He is a fighter, after all, and he is a vicious soldier.  We see him in battle as he "unseam'd" his opponent "from nave to chaps." 

The concept that two others (Malcolm and Donalbain, the King's sons) stand between him and even the possibility of the throne doesn't seem to enter his mind.  In Act I scene 3 he says, If chance will have me king, why, chance may crown me, without my stir."  One short scene later he is present when the Duncan names his oldest son Prince of Cumberland, successor to the throne; then he says, "Prince of Cumberland! That is a step on which I must fall down, or else o'erleap, for in my way it lies."  His latent ambition has turned to a hunger for the throne in a very short time--even without his wife's promptings. 

It's clear that Macbeth is a man who has ambitions to become king--and he quickly determines his general course of action and then carries it out.  Not surprisingly, the result of those actions is paranoia and eventual death. 

What influences Macbeth's changes throughout the play?

Shakespeare needed to have Macbeth change into a tyrant for the purposes of his plot. Macbeth's tyranny and rule by terror makes many Scottish nobles and commoners flee to England. This unrest in Scotland is seen as a threat to the stability of his own realm by the English king, and this is what motivates him to go to the expense of raising a big army to overthrow the tyrant. If Macbeth had been a kind and efficient ruler, the English king would probably not have interfered in Scottish politics in spite of the pleas of Malcolm and Macduff. The fact that Malcolm was the heir apparent to the Scottish throne would not have been sufficient in itself to move the English king to help him.

King Edward knows nothing about what really happened when Duncan was murdered. The story Macbeth tells is that Malcolm and Donalbain bribed Duncan's two grooms to kill the old man in his sleep so that Malcolm could become king and Donalbain could become next in line of succession and also profit by getting all sorts of endowments from his older brother. Then, according to Macbeth's story, the two brothers fled because they were afraid of being found guilty of murdering their father. King Edward would have no idea whether or not the story was true. For all he knew, Malcolm might have had his father killed so he could succeed him. But in any case, Edward would not feel justified in invading Scotland with what was then a huge army if Macbeth had turned out to be a wise and worthy ruler.

Macbeth's descent into tyranny is hard to explain. No doubt he had no intention of being a wicked ruler when he murdered Duncan. He probably hoped to salve his conscience by at least trying to be as good a king as Duncan had been. He says in a soliloquy in Act 5, Scene 3:

I have lived long enough. My way of life
Is fall'n into the sear, the yellow leaf,
And that which should accompany old age,
As honor, love, obedience, troops of friends,
I must not look to have; but, in their stead,
Curses, not loud but deep, mouth-honor, breath,
Which the poor heart would fain deny and dare not.

That must have been what he had hoped for if he became king--honor, love, obedience, troops of friends. He certainly couldn't have been hoping for what he actually got. The only plausible explanation for why he became such a hateful tyrant is that everybody knew he had committed the worst sort of treason and were recalcitrant because he was not the legitimate ruler. This then compelled him to rule by force and terror. Otherwise he could not get obedience. But the force and terror only made everyone hate him all the more.

What influences Macbeth's changes throughout the play?

Macbeth's transformation over the course of the play is profound. He begins the play as a noble, if ambitious Scottish thane, respected by his peers and held in high esteem by his kinsman, King Duncan. The king describes Macbeth as a "worthy gentleman" when he learns of his conduct in putting down a rebellion led by the traitor Macdonwald. Even when Macbeth discovers from the witches that he is destined to be King, he struggles with the implications of this fact. Indeed, he remains deeply conflicted even moments before he murders Duncan, acknowledging that only "vaulting ambition" motivates him to commit the deed. By the end of the play, however, he is a murderous monster, bereft of conscience. 

What exactly drives Macbeth is complex, and indeed this complexity is perhaps one of the reasons the play endures. On the one hand, the actions of the witches tend to suggest that malevolent supernatural forces are driving Macbeth to commit the wicked deeds that he does. On the other, there is no doubt that Macbeth is driven by extraordinary ambition. After learning of the witches' prophecy, he is driven to force the issue of becoming king by murdering Duncan. Finally, there is the role of Lady Macbeth, who goads her husband to murder by challenging his manhood when he vacillates. We are left to question whether Macbeth's descent into murder and evil is the consequence of fate, his own free will, or the ambitions of his wife. Perhaps it is best to say that a combination of the three leads the man down an ultimately self-destructive path, taking his family and closest friends with him.