A Crystal of Water

I kick at the door in rage. I'm eight and behind
the door my sister is taking a bath. Unfair!
I hadn't known I'd want to see her until she
set the lock. My heel hammers while her feet squeak
in the empty tub. We grow up in a day, a week
at most, baffled by what we cannot see.
Then, she's out, in a towel, with slicked back hair,
unconcerned, older, and so unkind.

I assume lots of little boys develop crushes on their older sisters.