The Night Thief by Barbara Fradkin
Local oddball Cedric "Ricky" O'Toole wants to know who is stealing vegetables from his garden. A raccoon? A bear?
Then the thief steals some horse blankets from the barn.
Not a bear, then. A kid.
A little kid, 10 years old, who is living nearly feral in a cave in the backwoods of Ricky's farm. Ricky does what most folks would do: takes the kid home, feeds him, gives him a bed and some clean clothes.
But because Ricky has some baggage with Children's Services, he doesn't call the authorities.
Then, Ricky finds the girl: older than the boy, and with a bullet hole in her shoulder.
A quick-moving narrative with a fast resolution, and better-than-usual quality writing for a 550-lexile book, but the author has Several. Points. To. Make. and isn't Subtle. About. Making. Them.
An adult protagonist is not a natural main character for the intended audience, but Ricky may be enough of an outsider to adult society that teen readers will accept him.
No cussing, no kissing. The blood is old, and the dead body (when they find it) is mostly taken apart by carrion feeders. Referrals to incest and child abuse, but nothing on the page.