the King.

Macbeth and Banquo together encounter the witches on the heath where Macbeth hears their prophecy for the first time. Banquo reacts as a friend would at the sound of Macbeth's good fortune, then seeks to know his own future. Shortly after, Banquo warns Macbeth of danger, explaining that the witches may not be trustworthy:

And oftentimes, to win us to our harm,

The instruments of darkness tell us truths,

Win us with honest trifles, to betray's

In deepest consequence.

By the end of Act I, Banquo still relates to Macbeth as his friend. Banquo has noticed a strangeness in Macbeth's behavior, but assumes it is merely a reaction to the new honor (Thane of Cawdor) he has suddenly received.

Macbeth and Banquo maintain their friendship into Act II, when Banquo mentions the witches. Macbeth lies, saying he never thinks of them, but tells Banquo that he would like to discuss them further. Macbeth then seeks to draw Banquo closer to him, inviting him to join Macbeth's cause when the time comes for him to become king. Banquo makes his position clear:

So I lose none

In seeking to augment it, but still keep

My bosom franchised and allegiance clear,

I shall be counseled.

With these words, Banquo sets limits on his loyalty to Macbeth. He will support Macbeth so long as he can do so with a clear conscience and an unguilty heart. Thus, Banquo's allegiance has been made conditional, a fact not lost on Macbeth.

After Duncan's murder and Macbeth's taking the throne, Banquo's suspicions are fully raised:

Thou hast it now: King, Cawdor, Glamis, all,

As the weird women promised, and I fear

Thou play'dst most foully for 't.

Banquo trusts Macbeth no more and dies shortly thereafter at Macbeth's command.

While Banquo and Macbeth don't make an appearance until Act 1, Scene 3, the audience is given an idea of what to expect about their relationship beforehand, in Act 1, Scene 2, when the captain is reporting on the state of the battle.  He focuses mostly on Macbeth's actions, but when Duncan asks if the captains, Macbeth and Banquo were dismayed by the threat against them, the wounded captain says they "doubly redoubled strokes upon the foe" and ended up winning the battle.  Through this report, the audience understands that both Banquo and Macbeth are brave, even when the odds are against them.  Neither of them turned and ran; rather, they stayed together, fought, and won.  This shows their loyalty to Scotland, and to one another.

When the two men make their first appearance in Act 1, Scene 3, they are returning from the battle and they encounter the Weird Sisters.  Immediately, they are both taken aback by the strange creatures in front of them, but upon hearing the prophecies directed at Macbeth, Banquo questions Macbeth's shock, saying "Good sir, why do you start and seem to fear/ Things that do sound so fair?" (54-55).  He then goes on to refer to Macbeth as his "noble partner" and asks the Weird Sisters to also speak of his future, saying he is indifferent to their favors and hate.  By calling Macbeth "noble," and inquiring about Macbeth's shock, Banquo reveals that he cares for Macbeth as a person, even beyond as a fellow soldier.

After the Weird Sisters disappear, Banquo confides that he cannot believe what they have seen.  The two men then restate part of the prophecies, attempting to make sense of them together.  Finally, when Ross and Angus enter and proclaim Macbeth the new Thane of Cawdor, Macbeth and Banquo are again taken aback.  In a brief aside, Macbeth asks Banquo if he has hopes his children will be kings, now that Macbeth has become the Thane of Cawdor (as the witches suggested he would).  Here we see a good sign of their relationship, as Banquo responds:

But 'tis strange
And oftentimes, to win us to our harm,
The instruments of darkness tell us truths,
Win us with honest trifles, to betray's 
In deepest consequence. (134-138)

This shows that the two men confide and trust in one another, and it also shows another aspect of their relationship, as Banquo offers wisdom and advice to Macbeth.  Finally, at the end of the scene, Macbeth again pulls Banquo aside and says that he would like to again speak privately about the Weird Sisters when they have a chance.  Banquo consents, and the men go on their way.

Even before we meet them, Banquo and Macbeth are established as very strong and loyal to Scotland.  Upon their entrance, they are shown to be loyal to one another.  As Macbeth turns on Scotland, ultimately ruining the country under his reign, Banquo shifts from friend to foil.

In Act III the relationship between Banquo and Macbeth has deteriorated since their encounter with the witches in Act I.

Banquo has demonstrated that he is a cautious man. After the witches have made their prophecies in Act I, Scene 3, Macbeth is persuaded by the appearance of truth in these predictions, noting that as the witches have said, he has become the Thane of Glamis and the Thane of Cawdor. Since these things have come to pass as predicted, Macbeth asks Banquo if he does not hope that the prediction that his sons will be kings will also come true. Not so easily swayed, Banquo cautions Macbeth against believing so quickly the words of the witches:

And, oftentimes, to win us to our harm,
The instruments of darkness tell us truths,
Win us with honest trifles, to betray's
In deepest consequence....(1.3.132-135)

Further, in Act II, Scene 1, Banquo's actions appear to reflect some anxiety. As he walks the halls of the castle at Inverness with his son Fleance, Banquo has cause to be nervous because he knows that Macbeth has readily believed in the witches' prediction about his becoming king without questioning the problematic nature of their other prediction of Banquo's future as the father of kings.

On the night of their arrival, Banquo asks his son Fleance if the moon is down and when Fleance tells him that it is, Banquo hands his son the sword he has been carrying, but as soon as he hears someone coming Banquo immediately takes it back. The person Banquo hears is Macbeth, who is still walking around even though the guest of honor, King Duncan, is "a-bed."

It is not long before Macbeth is confronted by Banquo holding his sword, asking "Who goes there?" Macbeth replies, "A friend" (2.1.10-11). Banquo then gives Macbeth a diamond necklace that the king has asked him to carry to Lady Macbeth as a gift for her hospitality. Banquo also tells his host that he dreamed the previous night of the "three weird sisters," adding, "To you they have showed some truth" (2.1.20). To this, Macbeth responds:

I think not of them.
Yet, when we can entreat an hour to serve,
We would spend it in some words upon that business,
If you would grant the time (2.1.22-25).

Here Macbeth suggests that he wishes to talk more with Banquo. Continuing, he says that if Banquo remains with him, there will be some reward for Banquo. Banquo replies that he will comply with Macbeth as long as nothing goes against his conscience:

MACBETH: If you shall cleave to my consent, when ’tis,

It shall make honor for you.

BANQUO: So I lose none
In seeking to augment it, but still keep
My bosom franchised and allegiance clear,
I shall be counselled.  (2.1.24-29)

As a result of this conversation, Banquo realizes that Macbeth intends to be king. Also, if Macbeth kills King Duncan in order to achieve this goal, then Banquo could be in danger, especially if he does not, as Macbeth has said, "cleave to [his] consent." (i.e. Remain loyal to Macbeth when the time comes). 

In Act III, Scene 1, Banquo speaks in a soliloquy. He acknowledges that Macbeth is king as the witches have predicted, but he fears that "Thou [Macbeth] play'dst most foully for 't" (3.1.2-3). Since he suspects that Macbeth has engaged in a foul deed in order to become king, Banquo wonders about how the witches' prediction about him may come to be. For one thing, he realizes that he would have to be dead in order for his sons to become kings. Consequently, Banquo loses his trust in Macbeth, especially in light of their conversation in Act II. Their relationship has now deteriorated to one that involves distrust and possible enmity rather than friendship. 

In Act III, Banquo has lost faith in Macbeth. As Macbeth's best friend and fellow general, Banquo should be his biggest supporter. However, when Macbeth asks him to provide loyalty, Banquo's response is cold and distant:

MACBETH To-night we hold a solemn supper sir,
And I'll request your presence.

BANQUO Let your highness
Command upon me; to the which my duties
Are with a most indissoluble tie
Forever knit.

Banquo does not offer his kinship freely; Macbeth must "command" him to do it. Macbeth has become the king and Banquo is now his subject and not his peer. Macbeth actually uses the royal "we" in referring to Banquo. English custom dictated that a king had two bodies, an earthly one and a heavenly one. Therefore, kings and queens used the plural "we" to refer to themselves. By using this pronoun in reference to Banquo, Macbeth is reinforcing the distance that now exists between them.

In Act I, Scene 3, Macbeth and Banquo are clearly good friends. This is the scene where the two men encounter the witches, who prophesy that Macbeth will become Thane of Cawdor and King, and that Banquo's sons will become kings. Referring to Macbeth as "trusted home," a term of endearment, Banquo urges Macbeth not to place too much stock in the prophecies:

But ’tis strange; 
And oftentimes, to win us to our harm, 
The instruments of darkness tell us truths, 
Win us with honest trifles, to betray's
In deepest consequence...

Macbeth clearly values his counsel, because he asks that they might speak again about what they have witnessed after they have both had time to think about it. 

By Act III, Scene 1, the murder of Duncan and Macbeth's accession to the throne have soured his relationship with Banquo. The scene begins with a soliloquy in which Banquo shows his fears that Macbeth is responsible for the murder of Duncan:

Thou hast it now: King, Cawdor, Glamis, all, 
As the weird women promised, and I fear 
Thou play'dst most foully for't...

Banquo is somewhat encouraged, however, by the fact that Macbeth's prophecy has come true, since the witches also predicted that his sons would be kings. Banquo tells Macbeth that he is going riding with Fleance, and Macbeth asks a number of questions that could cause the audience to (correctly) predict that Macbeth plans further foul play on Banquo's riding excursion. Banquo has become an obstacle to Macbeth's ambition, and must be eliminated. 

Banquo is the first to notice the witches, questioning them and making observations about what the witches look like.  Macbeth adds a one-line question: “Speak, if you can: what are you?”  Already, Banquo seems more able or likely to question and challenge the strange beings, while Macbeth seems almost speechless.

After the witches hail Macbeth as thane of Glamis, thane of Cawdor, and “king herafter,” Macbeth stands startled and silent. We know about Macbeth’s amazement because Banquo says:

Good sir, why do you start; and seem to fear
Things that do sound so fair?

Banquo goes on to boldly ask the witches what they have to say about his future:

Speak then to me, who neither beg nor fear
Your favours nor your hate.

The witches reveal to Banquo that his descendants will be kings although he himself will not. Then the witches vanish as Macbeth finally speaks and tries to ask them more detail about what they mean with their prophecies about him. Macbeth wishes they had stayed to explain.

Banquo and Macbeth may be almost laughing the incident off except that Ross and Angus enter to deliver the news that King Duncan has awarded the Thane of Cawdor’s title to Macbeth as a reward for his courageous support of the King in the rebellion.

Banquo warns Macbeth that the witches--”the instruments of darkness"--could be winning them with attractive truths while in reality, the witches intend to betray them:

But ‘tis strange:
And oftentimes, to win us to our harm,
The instruments of darkness tell us truths,
Win us with honest trifles, to betray’s
In deepest consequence.

The first prophecy has come true. Because the witches hailed Macbeth first as Thane of Glamis, the title he already possesses, Macbeth says to himself; that “two truths are told.”  If the first two are true, perhaps the prophecy about becoming king will be true, too.

Again, Macbeth seems more impressed by the witches and their prophecies than Banquo does. Does Macbeth have more ambition than Banquo? Has he already thought about becoming king? Macbeth thinks to himself that his hair seems to stand on end and his heart is pounding--he is already considering murdering Duncan:

My thought, whose murder yet is but fantastical...

In the meantime, Banquo stands with Ross and Angus; all three notice that Macbeth is lost in thought.  Banquo is not a fascinated about the prophecies as Macbeth. Banquo even calls Macbeth back to reality:

Worthy Macbeth, we stay upon your leisure.

Macbeth comes to himself and gives the other men a lame excuse about why he was so distracted:

Give me your favour: my dull brain was wrought
With things forgotten.

Thus in this scene we see that Banquo seems more practical and cautious in considering the witches and their prophecies. Macbeth seems initially more startled and even speechless when he first sees and hears the witches. When he see that the witches have spoken some truth, he becomes fixated on the idea of being king--and even briefly considers murder to get kingship. Banquo is not so impressed with what the witches have said and even warns Macbeth to be careful.

The language in Macbeth and Banquo's conversations with each other and their soliloquies in Act 3 shows that each is beginning to be suspicious of the other.

When reading Shakespeare, it is best to look for the broader meaning and not try to understand it word for word.  It is also helpful to read a summary of each Act beforehand, so you know basically what is going to happen.  We also have translated versions of the entire play here at enotes.  I have included a summary in the first link, a translated scene in the second, and an article on understanding Shakespeare's language in the third.

Macbeth and Banquo used to be friends.  When they are talking together in Act 1 they are easy with each other, laughing and talking.  However, by Act 3 the relationship has deteriorated into suspicion.

Each character has a soliloquy in Act 3 that shows he suspects the other.  In the beginning of Act 3, Banquo is talking to himself alone about how he feels that Macbeth has stolen the throne by killing Duncan.  He believes that Macbeth has played most foully for it (“Thou play'dst most foully for't”), or done terrible things to become king.

If there come truth from them— 
As upon thee, Macbeth, their speeches shine— 
Why, by the verities on thee made good, 
May they not be my oracles as well 
And set me up in hope? (Act 3, Scene 1)

Banquo is indicating Macbeth’s greatest fears that his sons, and not Macbeth’s, will be king after Macbeth, because the witches prophesized that too.  Macbeth gets annoyed that he has a “fruitless crown” and this is one of the reasons he decides to kill Banquo (and his son) to prevent his sons from being king.

When Macbeth enters, Banquo immediately becomes subservient, telling him his “duties [to Macbeth]/Are with a most indissoluble tie/Forever knit. (Act 3, Scene 1).  He is trying to make Macbeth think that he is not at all suspicious, and he is completely loyal to Macbeth.

Macbeth isn’t buying it.  He says that his “fears in Banquo/Stick deep” because he knows too much and is a threat to Macbeth’s family line keeping the throne.

’Tis much he dares,(55) 
And, to that dauntless temper of his mind, 
He hath a wisdom that doth guide his valor 
To act in safety. (Act 3, Scene 1)

Macbeth is already planning Banquo’s murder when he asks him if he is going out riding.  He will not kill Banquo himself.  He hired three murderers to do it for him.

Thence to be wrench'd with an unlineal hand, 
No son of mine succeeding. If't be so, 
For Banquo's issue have I filed my mind … (Act 3, Scene 1)

Macbeth can’t get the fact that Banquo knows about the witches and his sons are supposed to be king out of his mind.  He does not rest after killing Banquo though, because he sees Banquo’s ghost sitting in his spot, the embodiment of his fears, at the banquet.  Macbeth is so disturbed by the vision that the party has to be broken up early.

One way that Shakespeare uses language to present the relationship between Banquo and Macbeth is with allusion to earlier scenes and other plays, and use of pronouns.

In the beginning of the play, the witches greet us with this line.

Fair is foul, and foul is fair. (Act 1, Scene 1, enotes etext p. 8)

Of course, Banquo and Macbeth later encounter the witches.  When Banquo shares his suspicions, he says to himself.

Thou hast it now: King, Cawdor, Glamis, all,

As the weird women promised, and I fear

Thou play'dst most foully for't (Act 3, Scene 1, p. 10)

This is an allusion by Shakespeare back to the witches, and a play on words because the witches told us that fair would turn to foul, as it appears Macbeth has done.

This careful use of language continues.  In Act 1, Banquo reacts to the witches by wondering if he and Macbeth are hallucinating.

Were such things here as we do speak about?

Or have we eaten on the insane root

That takes the reason prisoner? (Act 1, Scene 3, p. 14)

Banquo uses the first person plural here, “we,” in order to involve both himself and Macbeth.  Later, he tries to include Macbeth in the conversation about the witches again, but Macbeth denies having thought of them.

I dreamt last night of the three weird sisters:

To you they have show'd some truth.(25) (Act 2, Scene 1, p. 27)

Macbeth rebuffs Banquo, saying he has not thought about the witches since then.  In this case, Banquo is trying to feel Macbeth out, and approach his suspicions head-on.  However, Macbeth will have none of it.  Banquo says “you” to Macbeth, meaning the witches showed Macbeth, and not Banquo, some “truth” about being Thane of Cawdor.  The focus is beginning to switch, from “we” to “you”.  This demonstrates that their relationship is starting to deteriorate.

Soon, Macbeth does not trust Banquo at all.  He compares Banquo to Mark Antony, and himself to Caesar.  He is sure Banquo will betray him, so he betrays him first.

He hath a wisdom that doth guide his valor

To act in safety. There is none but he

Whose being I do fear; and under him

My genius is rebuked…  (Act 3, Scene 1, p. 42)

This allusion to Mark Antony and Caesar is ironic, because he is the one who will betray Banquo.  He says that Banquo is the only one who can stop him, so he is ready to have Banquo murdered.

In Macbeth, Banquo and Macbeth are already beginning to be suspicious of each other before Macbeth sends the murderers to kill Banquo.

Macbeth and Banquo were brothers in arms and friends of a sort.  Both were soldiers that worked together.

First of all, Banquo was there when Macbeth got the prophecy from the witches that he would be king, and the prophecy also said Banquo’s sons would be king.  Macbeth complains that he was given a “fruitless crown” because Banquo’s sons and not his will be king (Act 3, Scene 1, enotes etext p. 42). 

When Macbeth finds out that Malcolm was named heir, he is annoyed.  He says that Malcolm is a step he must “fall down, or else o'erleap” because it lies in his way (Act 1, Scene 5, p. 18).  Basically, Banquo becomes the next step. 

Banquo is well aware that he stands in Macbeth’s way.  He is also beginning to wonder if he is a threat to Macbeth, because he suspects that Macbeth killed Duncan to become king.

Thou hast it now: King, Cawdor, Glamis, all,

As the weird women promised, and I fear

Thou play'dst most foully for't (Act 3, Scene 1, p. 40).

Banquo is concerned that Macbeth might do something to him.  His concerns are justified because Macbeth is indeed planning his murder.  Macbeth says of Banquo, “tis much he dares” (p. 42), because he believes that Banquo might move against him.

To be thus is nothing,

But to be safely thus. Our fears in Banquo

Stick deep, and in his royalty of nature

Reigns that which would be fear'd.  (Act 3, Scene 1, p. 42)

Basically, at this point the two old friends are both afraid of the other.  Each one is suspicious, and each one’s suspicions are justifies. 

http://www.enotes.com/macbeth-text

Macbeth and Banquo have always been firm friends and partners, though Banquo is very much the junior partner. The witches, however, hit on something fundamental when they hail Banquo as "lesser than Macbeth, and greater." In the battle at the beginning of the play, Banquo is everyone's second thought, his name tacked on to that of Macbeth. Duncan, greeting them both, says that Banquo has "no less deserved." A less magnanimous man than Banquo might think that he certainly has "less received," since Macbeth has been made Thane of Cawdor as a reward for his service while Banquo was given nothing. When Banquo and Macbeth talk to the witches, however, Macbeth deigns to traffic and parley with them, while Banquo treats them with the aristocratic contempt one would expect of a high nobleman and a great warrior.

In act 3, scene 1, Banquo has finally come to suspect and distrust his old friend. He is not specific about what he thinks Macbeth has done, but he is afraid that he has played "most foully" for the crown. Neither does Banquo know what he will do. He merely hopes that, since the witches' prediction proved accurate for Macbeth, it will be equally true in his case.

There is a brief, courteous, and constrained public parting between the two former friends. It is a grim irony that Macbeth reminds Banquo to "fail not our feast" and that Banquo's final promise to Macbeth is that he will be there, a promise he keeps in the most spectacular fashion.

We then see the contrast between Macbeth and Banquo at its most extreme. Banquo, noble, generous, and not particularly decisive, clearly distrusts Macbeth at this point but does not make any plans to act on his suspicions. Macbeth, meanwhile, has already laid plans to have Banquo and Banquo's son murdered. As with the witches, this brings Macbeth into contact with the dregs of society—the sort of men with whom Banquo would never have any dealings. Perhaps Macbeth thinks of this when he addresses the murderers in tones dripping with contempt:

Ay, in the catalogue ye go for men;
As hounds and greyhounds, mongrels, spaniels, curs,
Shoughs, water-rugs and demi-wolves, are clept
All by the name of dogs...

Though by this point in the play, the two men both distrust one another, Banquo has remained the same simple, honorable soldier he always was. He does not understand that the man who fought beside him is not only someone who has done an evil thing, but a thoroughgoing villain who has lost his honor. Macbeth's understanding of Banquo's noble character makes him hate Banquo all the more. Banquo, at this point in the play, is quite incapable of understanding Macbeth.

At the beginning of the play, Macbeth and Banquo are both soldiers in Duncan’s army.  Both are noblemen, and they are friends and colleagues.  By the third act, each suspects the other of standing in his way, and Macbeth kills Banquo.

In the first Act, Macbeth and Banquo are on fairly equal terms.   When they meet the witches, they are told that Macbeth will be Thane of Cawdor and then king, and Banquo’s sons will be kings.  Neither man appears to take the prophecy seriously, and Banquo seems more disturbed than Macbeth. 

When they get the news that Macbeth has been promoted to Thane of Cawdor because of his bravery in killing the traitor who previously had that title, Banquo’s response is “can the devil speak true?” and Macbeth asks why he is dressed in “borrow'd robes” (Act 1, Scene 3).  Yet Macbeth seems disturbed by Banquo’s reaction to the witches, and asks him if he doesn’t want his sons to be king.  Banquo replies that Macbeth’s interest in the crown seems to have been spurred, but he is concerned.

But ’tis strange; 
And oftentimes, to win us to our harm, 
The instruments of darkness tell us truths, 
Win us with honest trifles, to betray's(135) 
In deepest consequence— (Act 1, Scene 3).

When Macbeth and Banquo get the news, Macbeth is already wondering if Banquo is supporting him. 

Two truths are told

As happy prologues to the swelling act

Of the imperial theme!” (Act 1, Scene 3).

When he says this, he is NOT talking to Banquo. In fact, Banquo notices that he seems to be lost in thought.  Banquo already is getting concerned about the effects of Macbeth’s ambitions.  At this point, an interesting conversation takes place inside each of their heads, but not between them.  Macbeth thinks to himself “chance may crown me Without my stir” but Banquo is thinking that “new honors come upon him, Like our strange garments” (Act 1, Scene 3).  Macbeth thinks he might become king without doing anything else, and Banquo thinks Macbeth’s promotion does not fit very well.

When Macbeth acts, Banquo has already become suspicious of Macbeth's rise to king.  He is afraid that Macbeth has “play’dst most foully for’t” (Act 3, scene 1).  He notes that no one else seems to realize what Macbeth has done.  He also wonders if his prophecy will come true, and his sons will be kings.  This is not ambition on his part, but fear.  He knows he is a threat to Macbeth.

Macbeth is also suspicious of Banquo.  He is afraid that if his prophecy came true, so might Banquo‘s.  He is annoyed with his “fruitless crown” and realizes that he needs to get rid of Banquo if he is going to continue his line as king and have sons who are kings.  Macbeth decides the only thing to do is kill Banquo.