Hilary McKay

to think that fifteen would be nearly grown up,” said her sister Naomi, “until you started being it.”
Ruth knew exactly what she meant; she felt the same way herself and she thought the strangest thing about being so old was the fact that it made no difference at all. She was no more self-confident, or organised, or magically in charge of her emotions than she had been in the past. Nothing had changed; she was the same muddle-headed person she had always been, forever swinging between happiness and despair, never doing the right thing at quite the right moment. Naomi, eighteen months younger and two years behind her at school, had far more common sense.
Naomi was brainy, and a much more private person than Ruth [...] She and Ruth were very good allies; they understood each other. They read the same books, liked the same friends, detested the same enemies and managed to share a bedroom and yet remain on speaking terms most of the time. They endured with courage their little sisters Rachel and Phoebe.
“Although they really are insane,” remarked Ruth gloomily.
“Don’t be silly!” said their mother, although secretly thinking that Ruth had a point.

stuck a line of tape across their bedroom floor, dividing the enormous Max mess from the extreme neatness of Louis. Nothing could stop Louis seeing over the line, though, just as nothing could save Max from having to listen to Louis droning himself to sleep at night, like an out-of-tune mosquito.

“I am not your sister, and don‘t you dare put your disgusting spitty feet on my quilt.”
“All right,” said Louis, and rubbed them on Abi‘s bedside rug instead.
“You are truly disgusting,” said Abi severely, “and you should put those horrible pajamas in the washing basket.”
“What, now?”
“YES NOW!” said Abi.
Louis slid off the bed and disappeared, but came back much too quickly.
“I‘ve done it,” he said cheerfully.

... where a recorder club was tormenting a Christmas carol to shrieking ribbons, ...