“Well, for one thing, I always got out of doing the washing up,” she said. “And I was always too delicate to go to school much, if you remember.”

“All those washing ups I did,” I said. “And do you mean to say you never told anyone at all about it?”

She gave me an exasperated look. “That would have been pretty silly, wouldn’t it? The whole point was that no one knew.”

“And you’ve kept it a secret all these years,” I said.

“To tell you the truth, I hadn’t thought about it for years, till you brought it up just now. Of course, I really did have colds sometimes, and I did have those terrible chilblains in the wintertime.” She began to laugh, and so did I, but not very heartily.

Just then, two of her children began a battle under the windows, and she ran out to investigate them, leaving me to think about her duplicity all those years ago, when she was so small and frail it would have taken a strange-minded person to accuse her of the least offense, let alone of keeping the house in an uproar over her health for years on end. I was more admiring than anything else, because I hadn’t really minded doing the washing up alone, since I always received high praise from my mother for doing it, but I was stunned to think that Derry had been capable, so young, of thinking up and carrying through such a black and complicated plot, and of not speaking about it to anyone — not even to me.

It was then I remembered that this was not the first time she had set me back.

The first time it happened, she was not more than seven and I was almost nine. In those years, as I say, I was larger than she was, and I won’t say I bullied her, but I did boss her around. All her life, I bossed her unmercifully until the moment of which I am about to speak, and I suppose that even after that things did not really change very much between us. I remember I had a favorite game called “sitting on Derry.” I used to make her lie flat on the floor while I sat on her stomach and stared into her face, grimacing in a manner that we both considered terrifying. It was a simple game, but I suppose she must sometimes have grown weary of it.