This is of course the famous scene when Macbeth, during a banquet with his lords, is haunted by the ghost of Banquo, whom he has just had killed a few hours before. What is interesting about the role of Lady Macbeth in my mind is the way that she seems to change at the end of the scene when the Lords have left her alone with her husband from how she presents herself during the scene when Macbeth begins to act strange in front of her and the Lords that he is dining with.
During the banquet, we see Lady Macbeth berate her husband and tell him off in exactly the same way as she does in earlier scenes. She accuses him of cowardice and threatens and cajoles. Note the following lines:
This is the very painting of your fear:
This is the air-drawn dagger which, you said,
Led you to Duncan. O, these flaws and starts,
Impostors to true fear, would well become
A woman's story at a winter's fire,
Authorized by her grandam. Shame itself!
Why do you make such faces? When all's done,
You look but on a stool.
Such a rebuke is definitely the kind of thing we would expect Lady Macbeth to say. However, after the lords have left, when we would expect her to attack her husband verbally once again and try and tell him off for what he is doing, what is interesting is that she seems to be a rather passive character. She only says three lines, and does nothing to attack her husband or to comment upon his strange behaviour. This is very odd given her dominance and her criticism of her husband. She almost seems to be deliberately holding back and just observing her husband. Perhaps she recognises that he is impacted by her deeds and that she is losing power over him.