Lady Macbeth is portrayed as a complex character, who is both an extremely loyal, loving wife as well as a wicked, malevolent villain. Once Lady Macbeth receives the news regarding the witches' favorable prophecies, she immediately calls on evil spirits to consume her being in order to make her cruel, callous, and violent. Lady Macbeth's ambitious nature mirrors her husband's and she displays her loyalty to Macbeth by plotting Duncan's assassination so that he can usurp the throne. She not only masterminds the entire plot but also participates in the murder by placing the daggers back into Duncan's chamber following the assassination. Lady Macbeth goes on to display her loyalty and affection for her husband by reminding him to conceal his emotions and preventing the Scottish lords from suspecting his involvement in the murder. Despite her loyalty and affection for Macbeth, Lady Macbeth is a cold woman, who participates in a brutal crime. As the play the progresses, Lady Macbeth begins to gradually lose her mind and is overwhelmed with guilt stemming from King Duncan’s murder. Overall, one could argue that Lady Macbeth is a complex character, who is portrayed as both wicked and loyal to Macbeth at various moments in the play.

This isn't really an either/or question. The wonder and tragedy of this character is that she is both. She is a deeply loyal wife, and that leads her into being a monster. She loves Macbeth so much that she knows him and his character well, including that her character is harsher than his, so she must guide him to fulfill his destiny. She isn't pure monster, because she feels guilt so intensely that she scrubs imaginary blood off her hands.