Many People tend to lean towards evil tendencies as in many cases as crime does pay, and good people will lose out. This makes an evil person quite persuasive, as they would be able to offer larger prizes. Lady Macbeth uses these grand prizes to persuade Macbeth to kill Duncan as she realizes that he would not do it by himself:
“Yet do I fear thy nature; It is too full o' th' milk of human kindness \To catch the nearest way.”
This shows the relationship between Macbeth and Lady Macbeth. But you could also say that Macbeth sent the letter to Lady Macbeth knowing that she would take some form of action to persuade him, as the first thing he thought of was to kill the King.
In reaction to Macbeth’s letter, Lady Macbeth renounces all the soft, human parts of her own nature. In a play so full of supernatural events, we can take her literally when she says:
"...Spirits / That tend on mortal thoughts..." to "Stop up th' access and passage to remorse / That no compunctious visitings of nature / Shake my fell purpose..."
Perhaps Macbeth knew that Lady Macbeth was stronger and had needed her to force him on even when he was too afraid to continue.
After this scene, Lady Macbeth's singleness of purpose seems to prove that she has been successful in emptying herself of human feeling. When Macbeth tries to back out of committing the murder, she treats him with contempt. She questions his manhood and shames him into doing it.
Look at how effortlessly she lies. When Duncan, whom she plans to kill, arrives at the castle, her welcoming speech drips with false graciousness. While Macbeth has horrifying visions, Lady Macbeth seems cool and literal minded. To her, Duncan's blood is just something to be washed off her hands. Worrying over things you cannot alter is a waste of time. This is ironic as Duncan’ blood is what drives her insane causing her death by her own hand. She says:
“Out damned spot!/ …Who would have thought the old man to have so much blood in him?”
Additionally, this is parallel to Macbeth’s line after he kills Duncan, where he says:
“Will all of great Neptune’s ocean wash this blood/ Clean from my hand?”
This link is quite important as the blood on their hands symbolizes their guilt, where Macbeth forgets about it, his wife doesn’t.
To !?!?!?!?! towards the end of the play we see a change in Macbeth’s character, at first he was the one who had worried about being caught and the guilt had plagued his mind, which is why he needed Lady Macbeth to persuade him and keep him calm. We see this switch in roles when he says:
“I have almost forgot the taste of fears; /The time has been, my senses would have cooled/ To hear a night-shriek ”
This where Lady Macbeth dies after struggling with the guilt !?!?!?!?!?!?
But the question is if she was a victim or a manifestation of evil, In my opinion, I think she was more of a victim. I say this because she would not have committed suicide if she were fully evil. On the other hand, if Macbeth had known she would take action, is he the evil character who needed her to force him onward then discard after the murder. We see him then ordering the killers to assassinate his good friend, Banquo, his friend’s son, Fleance and Macduff’s family, and he does all of this without the consent or advice of his wife. In conclusion it is suffice to say that Macbeth was the manifestation of evil where Lady Macbeth was the victim.