In the play, Macduff is a Scottish nobleman who is the Thane of Fife. Amidst so many other secondary characters in the play, he stands out for suspecting Macbeth of regicide before anyone else. The very first instance when he delivers the news of King Duncan’s murder to others tells us of the faculty of practical affairs in him and his loyalty to the kingdom.
He has a sharp instinct. When all are leaving for the coronation ceremony of Macbeth, he leaves for Fife. He doesn’t even attend the banquet party in which Macbeth sees Banquo’s ghost after getting him murdered.
Macduff is a pragmatic character. He leaves for England and works for the greater good at the risk of the danger to which his family was exposed. His family is slaughtered but at the bidding of Malcolm, he is very quick at turning his “grief into anger” and springs into actions.
Macduff has a capacity to speak the truth in any condition and that’s what earns him the faith of Malcolm who tests his loyalty to the homeland by lying him about his own character. Malcolm is never afraid of showing his emotions in a Shakespearean England where men are supposed to act in a certain way to portray their manliness.
He is very humane and his capacity to feel outweighs that of Macbeth and at a basic level, he performs that heroic act of avenging the murder of his family and he parallels it with his duty to his homeland. Unlike Macbeth, he has no rhetoric of that level so, towards the final combat, he shouts “I have no words; my voice is in my sword.”
It is not clear in the play why he deserts his family at such a time to the dismay of his wife but one learns of his deep concerns for his family and country with equal sincerity. He finally places his faith in Malcolm as the true heir to the throne of Scotland. It means he has firm faith in the primogeniture aspect of the monarchy.