As this couple battles through this painful conversation about the "Home Burial," the power in the relationship shifts between the two. Sometimes, one person has all the power, and sometimes, it's the other. But most of the time it's somewhere in the middle, which makes things especially interesting. While they fight about their dead child, they also fight for control over the conversation, and control in their relationship.
The couple's position on the staircase symbolizes the power in their relationship.
The power in this poem is constantly shifting between the characters—at no point in the poem does one person have all of the power.