Fairytales (normal and mutated) certainly provide insight into step-mothers, absent fathers, and new siblings that get more love and attention. So our protagonist's progress through the world helps to turn him from a disaffected boy into a self-reliant semi-hero, while simultaneously, almost subconsciously, helping him to deal with his family issues.
If I thought Octavian Nothing was a YA novel that was probably too difficult for most YA, the Book of Lost Things is an adult work that might work well as YA fiction. Indeed the book was one of the ten books selected for the ALA's Alex Award, which is given to "adult books that will appeal to teen readers". That said, the book is dark and intense, and deals with adult issues of loss and grief. It is not for the kiddies, but certainly an enjoyable and well-written book.
I was a little faked out as I got to the logical denouement of the story, as there was still a third of a book remaining in my right hand. But there's a lot of optional end-matter that helps to explain Connolly's overall vision, though the work itself is clear enough. The afterword makes plain that there's an uncomfortable amount of painful autobiography hidden in its pages. And there's extensive discussions of each of the fairy tales that went into the book, and the role they played in the novel. These sections include canonical versions of the stories, which sometimes provide interesting tidbits as well, such as the fact that the Tale of the Three Bears originally featured not Goldilocks, but an old hairy woman.