Lady Macbeth dominates Act 1 Scene 5 with her ambitious nature. She formulates a plan to kill Duncan so her husband may ascend the throne and gain power. She cries, "[c]ome, thick night" (48), inviting the darkness, a symbol of evil, to give her power. Lady Macbeth desires to climb up the social ladder by whatever means possible. However, she feels that according to Elizabethan society, a woman is not capable of killing, whether it be murder or in battle. Nevertheless, she calls upon "spirits" (38) to "unsex me here" (39). Lady Macbeth is willing to become a man in her pursuit of power. Since this is not a feasible option, she shares her idea with Macbeth to inspire him to kill the King. Lady Macbeth's ambition, which she displays in her ruthless plot to kill the King to gain stature, is in contrast to her husband's kindheartedness and passivity. She "fear[s Macbeth's] nature" (14) and wonders if he is "too full o'th'milk of human kindness" (15). She perceives Macbeth as possessing too much compassion, which she thinks will prevent him from carrying out the murder of Duncan successfully. The relationship between Lady Macbeth and Macbeth is close in Act 1 Scene 5 because Lady Macbeth must work with Macbeth in order to carry out her plan to murder Duncan.
In Act 3 Scene 2, there is a change of roles from Act 1 Scene 5, as Macbeth controls the relationship, and Lady Macbeth feels remorse over the killing of Duncan. Lady Macbeth is disappointed with the life she now has as Queen, while Macbeth schemes the death of Banquo alone, fearing Banquo knows he killed Duncan. Lady Macbeth determines, "[n]ought's had, all's spent" (5). She feels remorse after plotting the murder of the king to obtain such a position of power as Queen. Her ambitious attitude that had been present shifts to one of defeat and discontent preventing her from gaining happiness and fulfillment. Macbeth also changes. He proclaims to his wife, "[w]e have scorched the snake, not killed it" (13). Macbeth is sure that by killing Duncan he has not solved all his problems. He now lives with the fear that he could be discovered for having killed Duncan. Acting upon this apprehension, Macbeth resolves to prevent himself from being uncovered by killing Banquo, whom he believes is suspicious. Macbeth's personality, driven by fear, changes from Act 1 Scene 5 to be more ambitious and ruthless. His actions are similar to Lady Macbeth in Act 1 Scene 5. Now it is a paranoid Macbeth who calls upon evil to help him with murder, as he beckons, "[c]ome, seeling night" (46). However, unlike in Act 1 Scene 5, Macbeth now plots alone to kill Banquo without his wife. She asks him, "[h]ow now, my lord, why do you keep alone"(8)? He no longer needs Lady Macbeth as she needed him in Act 1 Scene 5. Therefore, the relationship of the Macbeths grows apart. Nevertheless, there is no animosity between the two; Macbeth refers to Lady Macbeth as "dear wife" (36) and "dearest chuck" (45), both affectionate names. The rift in the Macbeths' relationship occurs as Macbeth reacts to his fears and schemes solutions, while Lady Macbeth questions the path they have taken.
In Macbeth, Shakespeare suggests that people driven by ambition can be affected by its corrupting power, leading them to commit crimes and evil acts. These actions can shape a personality in different ways; by making one regretful, in the case of Lady Macbeth, or distrustful and ready to carry out immoral actions, such as with Macbeth. Also, Shakespeare implies that evil actions taken to fulfill ambition can change relationships. A person whose vision is obscured with evil can lose sight of the importance of relationships and disregard others. It is human nature to be ambitious; however, Shakespeare scorns unrestrained evil desire.