How can I compare The Chrysalids and Macbeth from a "power" perspective?
This is a very interesting question that has obviously captured a key theme in both of these exciting texts. I have included links below to the enotes study guide section on both of these works that will hopefully help you to extend your analysis.
Let us begin by focusing on power in The Chrysalids. It is clear that the power if held by the Inspector and David's father, who represent a community that has a strict blueprint of what is acceptable and what is not. Note the Definition of Man that David recites to himself having met Sophie and discovering her secret:
"And any creature that shall seem to be human, but it not formed thus is not human. It is neither man nor woman. It is a blasphemy against the true Image of God, and hateful in the sight of God."
We can see that power is clearly held by those who have the right to determine such a blueprint, and who are charged with punishing such acts of "blasphemy." When we see the way in which Sophie was punished as a defenceless child for her "crime" of being a mutant, and the way that Sally and Katherine are tortured, this power becomes rather disturbing. Likewise the tyranny that David's father establishes in his household suggests that power is a primarily negative thing.
In Macbeth, it is an interesting question to ask who has power. Duncan as the king is shown to be weak an ineffectual. Macbeth himself at the beginning of the play shows that he is more under the power of his wife than anybody else. Clearly the witches are shown to have power that they use to interfere in the lives of mortals. However, as the play develops, it is clear that the more power that Macbeth gains, the more he is shown to be bloody and violent. Note the way that he starts off by killing Duncan himself, then moves on to persuading murderers to kill Banquo and Fleance in secret before slaughtering the entire household of Macduff. There is an escalation of brutality that mirrors his rise to power.
Therefore, in both texts, I would focus on the way in which power leads to inhuman acts of violence and bloody murder. Both texts point towards the danger of power and how it can cause us to lose sight of who we are as humans.