It's our first summer at grandmother house, and after our showers,
she inspects the dark condition of my sisters neck, declaring it fifthly. You're not cleaning right. We've got to get the dirt off you.
I peek through a cracked door as she and my sister wait over the tub until running water grows hot enough to kill bacteria. My sister kneels under the rush, a sinner prepared for baptism, while grandmother scrubs as religiously as she scours the toilet each Saturday.
Grandmother takes a break to wring and squeeze the towel free
of water, soap, and a bricklike, muddy dirt. Child, all that noise
isn't necessary. If you could see this nastiness, you'd be thanking me.
Seeing my sister's distress, I open the door wide. M'dea, I think
that's blood.
Grandmother quiets and bandages my sister well.I'm sorry, baby I didn't know you were that black
This is clearly a symbolic statement. In reality the grandmother will of course know how black her grandchild is. But in  metaphorical  terms, she may have underestimated the implications of being black in a white society. It is also a reference to sin, human moral frailty, which the child and her brother will have to battle with through life.
Detailing the nape