The boy living on the streets, seeking companionship and the need to protect (possibly the way he wasn’t), jealousy of a well looked after cat with a home, the use of crumbled up (thrown away) paper at the beginning and end of the book.
It’s a story of a boy who lives in an inner city, finds a young cat, and decides to take it home. They must travel through a gauntlet of dark and very scary incidents and places to get home.
The main storyline is about a boy whose older sister vanished many years ago when she wandered into the snow. She basically wandered out one night when it was snowing and never came back.
“There was not a boy on the wharf Johnny did not know. He had made friends with some and enemies of others, and had played or fought with all of them. […] Seemingly in one month he had become a stranger, an outcast on Hancock’s wharf. He was maimed and they were whole.”
“But my sister hadn’t meant to be naughty. She thought she had given the book-little-boy her own supper, and you know she was quite a greedy child, so it was a kind thing to do really.”
The Mouth-Organ Boys. This one was about a boy who wanted to belong to a group so badly that he couldn’t see the bad way they treated him. He can’t see that his mother is already giving him all she can and all he needs.
It’s not terribly unusual for a boy to have an imaginary friend, but Matthew’s parents have to agree that his—nicknamed Chocky—is anything but ordinary.