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.
He says he is testing him out. After saying how bad he is, he then flatters himself by saying how wonderful he is. Maybe one of the reasons was to make this self-flattery more believable.
suspects Macduff may be trying to deceive him, as he has already been betrayed by those close to him. Malcolm tests Macduff's intentions by pretending to be worse than Macbeth, to see if Macduff is truly loyal to Scotland. Once satisfied of Macduff's loyalty, Malcolm reveals his true self and the two join forces to overthrow Macbeth.
Malcolm advises Macduff to go out and fight to help place Malcolm on the throne. All Malcolm sees in Macduff's suffering is an opportunity to gain an ally.
Malcolm needs assurance from Macduff that he is truly loyal to Scotland and not attempting to deceive him as an agent of Macbeth. Malcolm tests Macduff's loyalty by pretending to be unfit for kingship, and once he is satisfied with Macduff's responses, he reveals his true intentions and readiness to lead Scotland.
Malcolm hesitates to accept Macduff's offer of assistance because he is testing Macduff's loyalty and sincerity. Malcolm wants to make sure that Macduff is truly loyal to him and not trying to trick or betray him. Additionally, Malcolm is feeling distrustful and cautious due to the corrupt and treacherous nature of the world around him.
Malcolm asks Macduff about his family to test his loyalty and see if Macduff is truly trustworthy. He pretends to be a tyrant like Macbeth to see if Macduff would still support him.
Macduff and Malcolm plan to overthrow Macbeth in England.
Both Malcolm and Macduff believe Macbeth is a tyrant to be overthrown. However, Malcolm is a tyrant himself, if not even more repulsive than Macbeth. Though Macduff is not fully aware of this fact. Malcolm manipulates Macduff into slaying Macbeth and then plea allegiance to himself as the King of Scotland.
By not committing to join Macduff in overthrowing Macbeth, Malcolm gains the opportunity to test Macduff's loyalty and dedication to the cause. It also allows Malcolm to assess Macduff's character and leadership abilities before fully trusting him in the rebellion against Macbeth.
Unlike his father who trusted too easily, Malcolm does not trust Macduff. He does not trust him because he thinks that Macduff may be secretly working for Macbeth. To test this theory he rambles lies giving examples of how he is not fit to be king. However, it is Macduff's polite reaction of disagreeing with Malcolm which makes Malcolm believe Macduff.
Malcolm trusts Macduff because he demonstrates his loyalty to Scotland and his opposition to Macbeth by joining forces with him to overthrow the tyrannical ruler. Macduff's courage and dedication to the wellbeing of Scotland earn Malcolm's trust and respect.
Macduff brings Malcom Macbeth's severed head.
Malcolm reveals to Macduff that Siward plans to attack Macbeth's stronghold at Dunsinane with ten thousand soldiers.