Are the Weird Sisters really sisters? And is the First Witch more powerful and important than the others?
The First Witch always seems to speak more than the other two. Also, in Act I Scene III, the Second and Third Witch offered to give the First Witch a wind to sail to the captain's ship. Were they being a suck-up because the First Witch is stronger? Or did they just want to help her to do this evil deed?
The three witches that we meet in Act I are all equally powerful and the first is not the leader of the other two. We meet the head of the witches, Hecate, who is not involved in the initial scene but comes in later on in the play.
"Later in III.v, Hecate lectures the witches for talking to Macbeth without involving her. In IV.i, when Macbeth pays another visit to the witches, Hecate has briefly appeared to the witches but leaves before Macbeth's arrival."
Hecate is the goddess of witchcraft and becomes angry with her sister witches, who are not real sisters, but sisters in the sense that they are all witches, because they have left her out of the plan to tempt and create conflict for Macbeth.
"Hec. Have I not reason, beldams as you are,
Saucy and overbold? How did you dare
To trade and traffic with Macbeth
In riddles and affairs of death;
And I, the mistress of your charms,
The close contriver of all harms,
Was never call'd to bear my part," (Shakespeare Act III, Sc V)
When Hecate, the head witch gets involved in the plot, the story moves very quickly to bring about Macbeth's downfall and death. So, Hecate is the most powerful of the witches, the fourth witch who does not appear in the beginning of the play.