Walk into nearly any bookstore or library at the moment and you will see a curated collection of Terry Pratchett's prodigious literary output. If you've never read a Terry Pratchett novel, there is no better time to begin; and if you don't trust me, then check out the testimonials from all of these well-known writers who have been influenced and entertained by his work.
Pratchett has always been an ideal writer for teenage readers. He's all for a judicious amount of anarchy, and few writers (if any) are more closely associated with a particularly irreverent style of humour. Pratchett writes about big ideas, and the complexity of human nature, but always with his inimitably light touch. He uses the limitless parameters of fantasy to ponder on serious things in a humorous, sometimes even silly, way. He is realistic about human nature, but never cynical. Pratchett understands that human beings will inevitably lower the tone, not to mention the occasion, but that they many unexpectedly rise to it as well.
Although he is best-known for his Discworld novels, Pratchett has also written several stand-alone novels for the Young Adult audience. Two of them, Nation and Dodger, are "more or less" historical novels -- both set during the 19th century. But this being being Pratchett, history gets tinkered with; especially in the case of Nation, where it is spliced with fantasy alternatives.
In Dodger, Pratchett recreates a recognisably Dickensian version of London and liberally borrows from (or pays tribute to, depending on how you look at it) one of Dickens' famous characters: the Artful Dodger, from Oliver Twist. To further blur the lines between fact, fantasy and fandom, Charles Dickens is himself a character in the novel -- in the substantial role as a journalist/writer and mentor to the title character. The entire novel is a wonderful Pratchett/Dickens amalgam: It's there in the language, that rather more ornate sentence structure associated with the 19th century; it's there in the characterization; and it's also there in highs and lows of Victorian society. As Dickens did in so many of his novels, Pratchett gives us a bottom-up view of things. Dodger, an orphan, is a tosher -- in other words, he makes his "living" by skimming through the sewers -- panning for gold through mud and muck. His aim is invisibility; and if that doesn't work, he has learned how to twist and turn his way out of trouble. Dodger is the embodiment of Pratchett qualities: practical, irreverent, resourceful, cheeky, but always very kind -- at least to those who deserve his kindness. Evil is always "having a go", as Pratchett might say, but it doesn't get to win.
One of Pratchett's most unusual novels is the award-winning Nation, which is an alternative history of our world set during the mid-19th century. It takes two natural disasters, a flu pandemic and a tsunami, and it sets up an intriguing series of "what if" scenarios in the shadow of Charles Darwin's game-changing discoveries. One of the main characters is Mau, the 13 year-old boy whose entire island nation has been wiped out when he is away completing his adult-initation ceremony -- which, fortuitously, involves building his own canoe. The other protagonist is Ermintrude, who manages to survive a shipwreck and takes that opportunity to change her name to Daphne. Without common language or culture, Mau and Daphne must learn to both communicate and cooperate with each other. Their mutual survival depends on it. And like every generation before them, they must decide what to keep and what to discard when it comes to the belief systems they have inherited.
Another reason why Pratchett is the ideal Young Adult author because he returns again and again to the theme of origins and rites-of-passage. There is self-knowledge in the sense of knowing where you came from; but more important by far is determining where you are going. In I Shall Wear Midnight, it is stated explicitly: the main thing about life is figuring out who you are and what you are good at. Sometimes, often, that means taking a firm stand. Tiffany Aching must solve a really big problem (literally a "trial by fire") entirely on her own. Older and more experienced witches watch from the sidelines, but it is always clear that Tiffany must act alone -- and with self-won wisdom. At the end of the novel, when she completes her task, she dons the black robes symbolising adulthood.
Terry Pratchett's final tweet stated the very simple and most classical ending: The End. But as with all great writers, his stories will endure . . . and are still waiting to be discovered by a whole new generation of readers.