When she learns of Duncan's approaching visit, she realizes instantly that Fate has delivered the King into her husband's hands, and invokes the powers of evil to ‘unsex her’, ‘make thick [her] blood’ and ‘stop up th’access and passage to remorse’ in order to carry out this horrific act. One may even suggest that this clearly shows she is evil and extremely ruthless.
On Macbeth's arrival she takes the matter into her own hands; she does not argue or persuade, but with quiet determination assures him that the day Duncan is due to leave ‘never Shall sun that morrow see!’ This demonstrates her as being cruel and merciless as the thought of killing does not seem to unnerve her, in fact, she is determined to arrange the gruesome details herself.
Lady Macbeth instructs her husband to ‘bear welcome’ in his eyes’ and ‘Your hand, your tounge; look like th’innocent flower, But be the serpent under’t.’ This quote shows that she is controlling Macbeth even though in the time the play was set, men would be more superior towards women. Furthermore, it has a Biblical reference when the serpent was actually Stan tempting Adam and Eve into eating the forbidden fruit, this is kind of similar to what Macbeth and Lady Macbeth are doing as they are planning to carry out a prohibited act. I think it shows that Lady Macbeth is mote dominant and controlling because she is convincing Macbeth to kill Duncan.
In conclusion, Shakespeare portrays Lady Macbeth as ruthless, cold hearted and merciless, due to her desperate want for the terrible act to be committed as soon as possible, and because her determination to plan Duncan’s death herself. . Her rejection of femininity and controlling of Macbeth represents her as being calculation and evil.