Philip Pullman's His Dark Materials series strikes an interesting balance with its intended audience - though the protagonists are young, the series deals with complex themes, most of which bemused young readers. That's by design; Pullman famously wrote the series as a response to other, more heavy-handed approaches to fantasy books for young audiences, and fully intended for them to be read by children and adults alike. Pullman examined deep existential and philosophical themes that served as the subtext for the darker and more violent storytelling. Pullman is far from the first author to tackle dark and complicated themes for children and teenagers, but he manages to do so in his own unique and complex way.
His Dark Materials' themes include love (with emphasis on an appreciation of life), anti-authoritarianism, and (of course) religion. Pullman has made no secret of his feelings about the works of authors like JRR Tolkien and CS Lewis, both of whom also wrote richly detailed fantasy worlds that espouse certain worldviews. In his series, he responds to those ideas not through satire or parody, but by offering philosophical alternatives. Children who grew up on these books might be surprised to learn about some underlying themes they may have missed while reading.
Most people know that CS Lewis's The Chronicles of Narnia was written as an allegory for various books of the Christian Bible. The Lion, the Witch, and the Wardrobe is a clear crucifixion story, while The Magician's Nephew handles Genesis and The Last Battle is reminiscent of Revelations. Philip Pullman, author of the His Dark Materials series, patently rejected that form of thinking.
Some read The Chronicles of Narnia as an attempt to lure children into Christian beliefs with fun and fantasy. His Dark Materials is clearly a rejection of those ideas, supported by the fact Catholicism is metaphorically chastised as it's represented by a corrupt religious sect in Pullman's work.
His Dark Materials takes its young protagonists seriously. In a series as complex as this one, it stands to reason Pullman would tackle the loss of innocence; part of the story concerns the accumulation of sin as an element called Dust, after all, and how it's attracted to children of a certain age.
However, instead of mourning the loss of innocence that comes with adulthood, His Dark Materials revels in it. The final book in the original trilogy, The Amber Spyglass, has its two main characters falling in love, re-enacting the Fall of Man, and immediately taking joy in the experience of gaining knowledge. Though their growth is bittersweet - just pages after they fall in love, they're told they can never be together - it's an honest look at the dichotomous nature of happiness.
It might feel unjust to young readers in comparison to a long-winded tome with a happy ending, but it's also a primer for understanding that even though things may not always work out, our experiences leave a lasting and indelible mark in which we can find both joy and sadness.
The first book in the series - The Golden Compass or Northern Lights, depending on where it's published - follows a young girl named Lyra as she journeys to the North to save her friend from a mysterious group called the Gobblers. As it turns out, these Gobblers are in fact connected with, though not exactly the same as, the Magisterium.
The Gobblers are conducting a frightening experiment in which they cut away children's daemons - spiritual companions, often said to represent souls, that manifest as shape-shifting animals until children reach a certain age. Once the daemons are cut away, the children essentially wither away, their personalities and vitality erased thanks to the absence of their souls.
Adults (attempting to eradicate sin) see no problem with cutting away children's souls until it's Lyra under the knife, at which point her mother, the person in charge of the experiment, puts a stop to it.
His Dark Materials ventures into biblical allegory the way The Chronicles of Narnia did, but in a decidedly different fashion. In The Amber Spyglass, Lyra takes on the role of Eve, with Will representing Adam. The two share a romantic and intimate moment in which Lyra, having recently talked to Mary about her love for the world and the feelings of first love and sexuality, feeds Will a piece of fruit. This represents both a sexual awakening and a sharing of knowledge, just as Eve and Adam experience in Genesis. However, the knowledge that they gain is celebrated - they find joy in knowing, and Dust (sin, knowledge, or whatever else it might also represent) returns to Earth.
Leaving the fate of the world to two children who could absolutely get it wrong is pretty terrifying for every adult, but it's also a beautiful moment that embraces the beauty of curiosity and knowledge and its ability to lead humanity forward.