Lady Macbeth appears as nothing less than monstrous in these scenes. Scene 5 features her soliloquy in which she begins planning the murder of Duncan and invokes all manner of evil spirits for the purpose. In Scene 7, she appears equally ruthless, urging her husband on to commit the murder. He is not entirely willing, but she jeers at him for being weak and declares that she herself would be quite prepared to kill her own baby if required.
In both scenes, Lady Macbeth comes across as not just wicked but grotesque, as she deliberately renounces humane traits like kindliness and mercy and all her own supposedly softer, womanly qualities, conjuring up a frightening picture of herself as filled 'from the crown to the toe top-full/of direst cruelty' (40-41) and with breasts full of 'gall' (46). She follows this up with the even grimmer image in Scene 7 of herself dashing out her baby's brains.
Lady Macbeth, then, appears as an utterly pitiless, scheming villain at this early stage, prior to the murder of Duncan. However, over the course of the play, this picture of her is not quite borne out. After the murder of Duncan she gradually becomes unhinged with remorse, as her famous sleepwalking scene, when she desperately tries to wash her hands free of blood, attests. In the end, she is not really fitted for such villainy. Although she appears so evil in the scenes discussed above, what she is really doing is trying to work herself up to the pitch of committing murder, to psyche herself up for the dreadful task. It doesn't really come naturally to her.