Martha (still softly): I said, make me a drink. George (Moving to the portable bar) Well, I don't suppose a nightcap'd kill either on of us…(1.54-1.55)
This the first of the many drinks George makes for Martha. No matter how bad they're fighting he seems to always be willing to booze her up. Does this show that Martha has power over him? Perhaps, though, by making the drinks he is preying on her alcoholism, which then gives him power over her.
Martha: George […] is and old bog in the History Department. (1.448)
George's failure to advance in his career is the main weapon Martha wields in their battle for power.
Martha: I got into a pair of gloves myself. […] I let go sort of a roundhouse right […] CRASH, [George] landed…flat…in a huckleberry bush! (1.502-1.504)
Martha takes delight in telling this story, probably because it emasculates George. The fact that George got beat up by his wife definitely caused George to lose some power.
Martha: Our son does not have blue hair…or blue eyes, for that matter. He has green eyes…like me. George: He has blue, eyes Martha. (1.675-1.676)
Here George and Martha use the illusion of their son as a battlefield for dominance.
George: I've been drawing you [Nick] out on this stuff, not because I'm interested in your terrible lifehood, but only because you represent a direct and pertinent threat to my lifehood (2.217)
George openly admits that he's intimidated by Nick's youthful potential, and that he's seeking a way to undermine it.
Martha: You want to know what big brave Georgie did? George: (Advancing on her) You will not say this! […] Martha: He came home and he threw the book in the fireplace and burned it! (2.476-2.479)
Revealing the secret of George's novel is a major power play on Martha's part.
George: I'll tell you what game we'll play. We're done with Humiliate the Host[…]How about a little game of Get the Guests? (2.510)
George attempts to regain power by humiliating Nick and Honey. He uses what Nick told him about Honey's hysterical pregnancy against them.
Martha: You know what I'm doing, George?[…]I'm necking with one of the guests.[…] George: Good…good. You go right on. (2.783-2.787)
By pretending to not care about Martha's infidelity, George gains power over the situation.
Martha: The gelding's all upset. Ha, ha, ha, HA! […] Go answer the door.[…] You [Nick] can be houseboy around here for awhile. (3.61-3.75)
We wonder if Martha is only bossing Nick around because he failed in bed. There's a chance she would've treated him this way no matter how their trip to the bedroom turned out. Look at how she treats George.
George: We got a telegram; there was a car accident, and he's dead. POUF! […] Martha: (A howl which weakens into a moan) NOOOOOOoooooo. (3.449-3.450)
The power struggle that has driven the action of the play ends here. By destroying the illusion of the child he gains full control. Martha is defeated, but at what cost? Will they recover?