Andrew Martin's recent article on the ways fathers are depicted in popular culture and particularly children's and YA literature is an interesting read.
While I strenously disagree with his take on Dodie Smith's 'I Capture the Castle' ("Cassandra's father borrows his daughter's coloured crayons in order to plan his supposed epic; and she solicitously provides him with glasses of milk. He is completely broke, in spite of that castle, which he doesn't own, but only rents.") he does nail the point that absent or ineffectual parents are almost necessary to children's fiction, particularly the fantasy-tinged variety. After all, when does anything interesting happen when your parents are around? From the piggish parents in Roald Dahl's 'Matilda' to whoever the parents are in The Famous Five, from Harry Potter's dead, heroic, parents to Mr and Mrs Darling, lack of parental oversight is integral to adventure.
Often however there's the stand-in adult, the adult who seems more on the side of the child than the grown-ups. From Merlyn in 'The Sword in the Stone' to Mary Poppins, or the great uncles of 'The Lion, the Witch and the Wardrobe' and the 'The Dark is Rising', these characters are shaman-like figures, guiding children between worlds.
There are though some books that draw warm, insightful relationships relationship between parents and children, Roald Dahl's 'Danny, Champion of the World', Rebecca Stead's 'When You Reach Me', Michael Chabon's 'Summerlands', and the most searing account of parenting I've ever read, Cormac McCarthy's 'The Road'.