Son
Macduff's son exists to make the horror of Macbeth's tyranny personal and irreducible. His death is not political — it is simply a child being killed. The scene is Shakespeare's most direct appeal to the audience's basic human feeling.
Appears In
Biography
Macduff's son appears in a single scene alongside his mother, moments before both are murdered by Macbeth's men. He has no name in the play — he is identified only as 'Son' — but Shakespeare gives him some of the sharpest dialogue in Act IV.
His exchange with Lady Macduff about traitors, liars, and hanging is conducted with the relentless logic of a child who has not yet learned to pretend. He is unafraid, curious, and entirely without the caution that the adult world of the play has learned the hard way. This makes him both comic and devastating in the same breath.
When the murderer arrives and calls his father a traitor, the boy calls the murderer a liar and is killed for it. He is brave in the only way a child can be — without understanding the stakes.
Motivation
He is a child defending his father's name. That is all.
Personality
The boy argues like a small philosopher and dies like a small hero. His fearlessness is not courage — he doesn't understand the danger — but the effect is the same. He is one of Shakespeare's most economically written characters: fully alive in a few dozen lines.