Lady Macbeth fulfills her role among the nobility and is well respected like Macbeth. King Duncan calls her "our honored hostess." She is loving to her husband but at the same time very ambitious, as shown by her immediate determination for Macbeth to be king. This outcome will benefit her and her husband equally. She immediately concludes that "the fastest way" for Macbeth to become king is by murdering King Duncan.
Lady Macbeth's immediate thoughts may make her appear as thoroughly irreligiously cold and ambitious, but this is not so. To prepare for what she feels must be done she calls on evil spirits to "stop up th' access and passage to remorse" in order to be relentless. Otherwise her conscience would not allow her to act.
Furthermore, Lady Macbeth knows her husband well. She thinks he may be too kind in order to murder King Duncan. This is why she represses her conscience so she can later usher Macbeth into commiting the deed. At first Macbeth agrees. But later Macbeth wavers in his decision. But Lady Macbeth is sure that being king is what Macbeth really wants and that this is the best for both of them. So, in response to Macbeth's uncertainty, Lady Macbeth manipulates him by questioning his manhood and his love for her. She is successful because regardless of his own conscience Macbeth carries out their plan of murder.
The almost superhuman strength Lady Macbeth rallies for the occasion and her artful and sly ability are shown through her meticulous attention to detail regarding the murder. When Macbeth returns to their chamber she goes back to the murder scene and cleverly smears the grooms with Duncan's blood. However, her morals had prevailed just a while before as revealed through her comment that she would have killed Duncan herself had he not "resembled [her] father as he slept."
Perhaps Lady Macbeth felt that suppressing her conscience for the deed was enough and that later the thought of the deed would just dissipate. The outcome is not this way, though, because Macbeth and Lady Macbeth often cannot go to sleep, and if they do, they experience terrifying dreams. But still, Lady Macbeth is able to maintain her sanity and composure during the day, even more than her husband. She urges him to be light hearted and merry. Once she practically rescues Macbeth from the frailty of his own conscience. When Macbeth sees Banquo's ghost she creates an excuse to explain his odd behavior. She attempts to chasten Macbeth by again questioning his manhood. When the situation grows worse though, she takes charge once more and promptly dismisses the lords from the feast.
Later, though, the burden of Lady Macbeth's conscience becomes
too great for her and her mental and physical condition
deteriorates. A gentlewoman observes her sleepwalking and
consults a doctor. The doctor and the lady observe Lady Macbeth
sleepwalking, madly trying to cleanse her hands of the blood of
Duncan and Macduff's family. Still in her sleep, Lady Macbeth
asks, "what, will these hands ne're be clean?"
foreseeing that she will never have peace of mind. She also
retells events of the day Duncan was murdered. The doctor tells
the gentlewoman that what Lady Macbeth needs is spiritual and not
Lady Macbeth's condition worsens, and she goes in and out of sleep with delirious visions. Macbeth asks the doctor to cure her or give her a drug that will erase the troubles of the heart. The doctor responds that he cures physical not moral problems. Later, as the battle ensues outside of Dunsinane, by unspecified means Lady Macbeth commits suicide.
At the beginning Lady Macbeth finds strength to entice Macbeth to murder Duncan and to follow through with the murder herself. As time advances though, her pretended strength diminishes as she fights the torments of her conscience. Tending to her conscience engulfs and destabilizes her so that she can not support Macbeth against Malcolm. Lady Macbeth's attempts to suppress her conscience fail. At the end she chooses death because she can no longer bear the torments of her guilt.