Lady Macbeth's character is used to challenge ideas surrounding femininity and challenges gender norms, yet she rises to her stereotype when it suits her
Similarly to Macbeth, Lady Macbeth's character acts as a warning to the audience. A warning against unnatural ambition and aligning with the supernatural. This came in the form of her insanity that later resulted in her death
Her character is there to encourage and manipulate the (somewhat) weaker Macbeth. Without Lady Macbeth's influence, it is debatable as to whether Macbeth would have ever committed regicide