Double Dexter by Jeff Lindsay

my brow and a loud cry of,
Retro me, Brianus!
But before I could decide which choice to jump at, life intervened, as it usually does, and made the decision for me.
    “Dexter!” Astor yelled from down the hall, with all the fury of a very cranky eleven-year-old girl. “I need help with my math homework! Now!”
    I looked at Brian and shook my head. “You’ll excuse me, brother?” I said.
    He settled back into the sofa and smiled, the old fake smile again. “Mmm,” he said. “Domestic bliss.”
    I got up and went down the hall to help Astor.

SEVEN
    A STOR WAS IN THE ROOM SHE SHARED WITH CODY, HUNCHED over a book at the little hutch that served them both as a desk. The expression on her face had probably started life as a frown of concentration, and then evolved into a scowl of frustration. From there it had been just a short jump to a full-blown menacing glare, which she turned on me as I came into the room. “This is
bullshit,
” she snarled at me with such ferocity that I wondered whether I should get a weapon. “It doesn’t make any sense at all!”
    “You shouldn’t use that word,” I said, and rather mildly, too, since I was quite sure she would attack if I raised my voice.
    “What word,
sense
?” she sneered. “ ’Cause that must be a word they forgot in this stupid book.” She slammed the book closed and slumped down in the chair with her arms crossed over her chest. “Bunch of crap,” she said, looking at me out of the corner of her eye to see whether she would get away with “crap.” I let it go and went to stand next to her.
    “Let’s take a look,” I said.
    Astor shook her head and refused to look up at me. “Useless dumb crap,” she muttered.
    I felt a sneeze coming on and fumbled out a tissue, and still withoutlooking up she said, “And if I get your cold, I swear.” She didn’t tell me what she swore, but from her tone it was clear that it wouldn’t be pleasant.
    I put the tissue in my pocket, leaned over the desk, and opened the book. “You won’t get my cold; I took a vitamin C,” I said, still trying for a winning note of lighthearted and tolerant reason. “What page are we on?”
    “It’s not like I’ll ever have to know this stuff when I’m grown up,” she grumbled.
    “Maybe not,” I said. “But you have to know it now.” She clamped her jaw and didn’t say anything, so I pushed a little. “Astor, do you want to be in sixth grade forever?”
    “I don’t wanna be in sixth grade
now,
” she hissed.
    “Well, the only way you’ll ever get out of it is if you get a passing grade. And to do that you have to know this stuff.”
    “It’s
stupid,
” she said, but she seemed to be winding down a bit.
    “Then it should be no problem for you, because you’re
not
stupid,” I said. “Come on; let’s look at it.”
    She fought it for another minute or so, but I finally got her to the right page. It was a relatively simple problem of graphing coordinates, and once she calmed down I had no problem explaining it to her. I have always been good at math; it seems very straightforward compared to understanding human behavior. Astor did not seem to have a natural gift for it, but she caught on quickly enough. When she finally closed the book again she was a lot calmer, almost contented, and so I decided to push my luck just a bit and tackle another small item of pressing business.
    “Astor,” I said, and I must have unconsciously used my I’m-a-grown-up-here-it-comes voice, because she looked up at me with an expression of alert worry. “Your mom wanted me to talk to you about braces.”
    “She wants to ruin my life!” she said, hurtling up into an impressive level of preteen outrage from a standing start. “I’ll be hideous and no one will look at me!”
    “You won’t be hideous,” I said.
    “I’ll have these huge steel
things
all over my teeth!” she wailed. “It is
so
hideous!”
    “Well, you can be hideous for a few months now, or hideous forever