Manipulation is the order of the day in Macbeth and Macbeth himself, initially encouraged by Lady Macbeth and the witches, will use all means to secure himself as king of Scotland.
There are legitimate reasons for Macbeth to become powerful as his valor on the battlefield is recognized. He is undeniably ambitious by his own admission, recognizing his "vaulting ambition." Duncan, as King of Scotland, rewards Macbeth for his military achievements which co-incides with the witches prophesies. After that, "no fair and foul a day" will aptly describe the occurences and enhance an understanding of Macbeth.
After Macbeth's initial reluctance and decision to "proceed no further in this business"(I.vii), his own power is thwarted as Lady Macbeth suggests that it is weakness that stops him and he "would be so much more the man" if he goes through with their (her) plans to murder Duncan.
Macbeth is already influenced by the witches and is happy to
embrace the weird sisters' vision of him as the ruler of all Scotland
The power that this apparently bestows upon him, makes him think that he can escalate his rise to the throne of Scotland so Lady Macbeth has only to question him to make him strive for more power. At this point, he is still very much a team with Lady Macbeth and any power he exerts and uses is to please her.
As the play progresses, Macbeth, in his confused state and overwhelmed by the power he feels now that he has murdered Duncan and has not been blamed, uses this new found power to further his own gains; hardly considering Lady Macbeth but still needing reassurance from the witches. The fact that Macbeth can sleep no more" (II.ii.) serves to compound his guilt but not enough to make him stop.
Macbeth, concerned about Banquo and how this - or his sons- may ruin his plans as the witches prophesied that Banquo's "children shall be kings"(I.iii), thinks nothing of arranging for the murder of Banquo. Fleance, who should have died with his father, escapes and Macbeth is haunted by Banquo's ghost more because he is worried that Fleance will reveal Macbeth's guilt rather than from any remorse.
Macbeth feeling so powerful does not feel the need to involve Lady Macbeth "Be innocent of the knowledge" (III.ii)in the murder of Banquo. The two become less aligned as the plot continues. Lady Macbeth becomes more haunted by their actions, driving her to madness
more needs she the divine than the physician(V.i)
whereas Macbeth's madness is more subtle, expressing itself in murder after conspired murder. No man "of woman born" can impede his progress.
He seems to forget the consequences towards the end as he feels invincible. Even Lady Macbeth, as she tries to comfort him "give me your hand … to bed, to bed, to bed" (V.i) and her ultimate death which saddens him, cannot stop him. Even when all seems lost, after her death, "signifying nothing" his quest for power goes on until he is defeated.