There are many things to consider when thinking about who is to blame, for example:

• Whose idea is Duncan's murder?
• Who is the stronger - Macbeth or Lady Macbeth?
• Whom do we pity?
• Are Macbeth and Lady Macbeth a team, and if not, when do things change?

Macbeth

• He already harbours thoughts of the kingship.
• He willingly listens to the witches.
• He writes to his wife to excite her interest.
• He begins to back off when the plan has been hatched.
• He takes over the planning from Lady Macbeth.
• His speech is full of evil, threat and darkness.

Lady Macbeth

• She is obsessed with the news sent by Macbeth.
• She immediately hatches a plan.
• Her speech is full of evil double meaning.
• She taunts Macbeth when he tries to back down.
• She takes the knives back to the servants after the murder.
• She tries to make everything normal again afterwards.

The witches

• They select their target precisely.
• They speak Macbeth's thoughts.
• They make him believe his greatest prize is near.
• They show him they have the power of prophecy.
• They torment him with riddles.