He was testing Macduff to see if he genuinely had the interest of Scotland at heart. When Malcolm says "He hath not touched you yet" (IV, iii, 14) it means that he suspects Macduff is in league with Macbeth to take him prisoner and kill him. Malcolm then makes up all his vices to make sure that Macduff wants a good king and not just Malcolm. When Macduff responds that with his vices, Malcolm would make a terrible kind, Malcolm responds that he made the vices up and he knows that Macduff has Scotland's best interests at heart.
Because they were mad at him, they wanted to kill him and make Malcolm king instead.
The witches show Macbeth a procession of Banquo's descendants as kings.
Macduff assumed at first that Malcom and Donalbain hired the soldiers to kill their father and they fled to avoid any confrontations. However, it is evident that they fled because they suspected that they were the targets of a conspiracy.
Malcolm goes to England and Donalbain goes to Ireland (and that's the last we hear of him). They are taking a powder, believing rightly that they will be suspected of murdering their father. Ross, who loves to find out and deliver news, is going to Scone to check out Macbeth's coronation. Macduff, who doesn't like Macbeth much and is anyway somewhat antisocial, goes home to Fife. There he will make a point of refusing invitations to Macbeth's dinner parties.
Malcolm is testing Macduff's integrity. If Macduff had embraced Malcolm's worldly, unethical responses, Malcolm would not have trusted him enough to form an alliance with him. When Macduff wails at the imminent hopelessness of Scotland, Malcolm knows he is in the presence of a good man, and he reveals his own "innocence" and stalwart loyalty to Scotland and to God.
He was testing Macduff to see if he genuinely had the interest of Scotland at heart. When Malcolm says "He hath not touched you yet" (IV, iii, 14) it means that he suspects Macduff is in league with Macbeth to take him prisoner and kill him. Malcolm then makes up all his vices to make sure that Macduff wants a good king and not just Malcolm. When Macduff responds that with his vices, Malcolm would make a terrible kind, Malcolm responds that he made the vices up and he knows that Macduff has Scotland's best interests at heart.
Because they were mad at him, they wanted to kill him and make Malcolm king instead.
Malcolm deceives Macduff by claiming to be unfit for kingship in order to test Macduff's loyalty and commitment to overthrowing Macbeth. Malcolm wants to ensure that Macduff is not in league with Macbeth before revealing his true intentions of leading the fight against the tyrant.
Malcolm told Macduff that he was greedy, and lustful and had absolutely no desire to be king. He even tried to convince Macduff to accept the opportunity to become king but instead Macduff turned down the offer and told Malcolm that despite all of his bad qualities he would still make an excellent king.
Malcolm suspected Macduff of having designs on the crown and throne of Scotland. In Act 4 Scene 3, Macduff had arrived in England from Scotland. He had joined the group of discontented Scotsmen that had formed around the subsequent King Malcolm III [d. November 13, 1093]. Malcolm wanted to take the throne of Scotland away from Macbeth [c. 1014-August 15, 1057]. He wanted someone else to kill and behead Macbeth. But he didn't want Macbeth's murderer to gain the Scottish crown and throne. Malcolm knew that Macbeth had had Macduff's entire family and household murdered. So he wanted Macduff to be Macbeth's murderer. But he wanted to make sure that Macduff would do the killing only to avenge his lost family and household. He wanted to make sure that Macduff wouldn't try to claim the crown and throne as his.
or it could be that malcom didnt trust macduff because Macbeth hadnt touch macduffs family yet. and when Macbeth had macduffs family murdered..that's when the trust came,Macduff says he's loyal and trustworthy.Still, Malcolm's a little paranoid so he decides to test Macduff by suggesting that even he, Malcolm, might make a poor king, were they to defeat Macbeth. Scotland would suffer, he says, under his own bad habits. Malcolm claims to have an impossible lust that would only get worse as he devoured all of the maidens of Scotland.Macduff at first insists there are plenty of maidens in Scotland, and Malcolm would be satisfied.Malcolm presses further about how bad he would be as king, and Macduff finally despairs that Scotland apparently is going to be in trouble either way.Malcolm then relents because he sees Macduff is truly devoted to Scotland, not to a political alliance
Macduff brings Malcom Macbeth's severed head.
The future King Malcolm III [d. November 13, 1093] wanted the throne of Scotland. He didn't want to make the mistake of his father, King Duncan I [d. August 14, 1040], and trust the wrong people. Indeed, his father had trusted Macdonwald, who rebelled against his sovereign and his country; the Thane of Cawdor, who betrayed his king and his country to King Sweno of Norway; and Macbeth, who killed him. So Malcolm wanted to make sure that Macduff had no ambitions other than to avenge the murder of his entire family and household under Macbeth's orders.Also, Malcolm's theory was that Macduff praised Macbeth highly (and the feeling was returned), even though he is now a victim of Macbeth's tyrannical power (when Macbeth had his family killed). "This tyrant .../was once thought honest, you have loved him well" (12-13); it is because of the reasoning presented in this quote that Malcolm thinks that Macduff might want to betray him to Macbeth.
Macbeth was killed by Macduff because Macbeth had send men to kill (successfully) Macduff's wife and son. Also, since Macbeth was the tryant ruler of Scotland, Macduff (and the English forces brought by Malcom) were in battle with Macbeth and his men.
At the start of the play, before meeting the witches, Macbeth is still loyal to Duncan. The forces of Norway and the rebel Macdonwald (whom he kills in battle) could be considered his adversaries at this point in the play. After he meets the witches and begins to entertain thoughts of regicide, anyone who stands between him and power becomes his adversary (Duncan, Malcolm, Banquo, Macduff...) One could probably make an argument as to why Lady Macbeth might be considered Macbeth's adversary as well.
The witches show Macbeth a procession of Banquo's descendants as kings.