The protagonists of fantasy novels tend to be special. They may be magically gifted, or born into a royal family, or the subject of a prophecy; in the most extreme case, they may even have been picked out by the gods to fulfil a special destiny. Or, like Elisa, heroine of Fire and Thorns (The Girl of Fire and Thorns in the US), they may be all four at once. On the day she was named, a divine light shone down upon Elisa and a magical blue jewel—the Godstone—appeared in her navel, marking her out as a "bearer," a kind of special servant of God who is born once a century to perform a divine Service. In response, her parents, the king and queen of Orovalle, decided to name her "Lucero-Elisa"—"heavenly light, chosen of God."

With a backstory like that, it would have been unsurprising if Elisa had turned out to be insufferably perfect, smug, and self-assured, since not only are all the signs pointing to her having a Special Destiny, but these are signs visible to the characters as well as the reader. Yet far from being smug, Elisa is riven with self-doubt and self-loathing, having felt unworthy all her life of the privilege of bearing a Godstone, and being perpetually overshadowed by her older, prettier, more confident sister. Elisa deals with her misery by overeating, as a result of which she is immensely fat—which doesn't help her self-esteem one bit. As the novel opens on her sixteenth birthday, she is struggling to fit into a wedding dress which is too small for her so that she can marry a king she has never met for reasons of state she does not understand—a neat embodiment of all the ways in which she is powerless: she has no control over her relationships, over the direction of her life, or even over her own body. Even though the Godstone is essentially a sign that says "your life has a purpose!" in giant letters, Elisa has no real idea what's going to happen to her or what she needs to do, and she trembles at the thought that she might somehow prove inadequate for whatever task is set for her.

Appropriately, the concept of fate is very much at the fore in Fire and Thorns, though early on, the grim revelation that many previous bearers of the Godstone died before completing their Service cuts off any possibility of Elisa passively waiting for fate to unfurl. She may well be chosen by God, but God's not going to step in on her behalf if she doesn't prove herself worthy. What's more, she has received no guidance whatsoever to help her become worthy, due to a religious belief on the part of the people of Orovalle that the bearer must be kept in ignorance. Conveniently for the story, this belief prevents Elisa from learning about the prophecies concerning the bearers until she arrives in her husband's country of Joya d'Arena. She immediately starts studying them, while trying to feel her way through the hazardous politics of the court. But both her attempts to claim a place in the court and her study of the prophecies are cut short when she is kidnapped and taken across the desert to a beleaguered border province. The province is constantly under attack by Invierne, ancient enemy of Orovalle and Joya d'Arena, and Elisa's kidnappers believe she is their last hope; that somehow (they are not sure how) she or the Godstone can save them from the Inviernos and their sorcerers. The prophecies, indeed, hint at something along those lines, but they are confusing and vague and their meanings are unclear except in retrospect.

This is typical for literary prophecies, but in the context of the story Carson is trying to tell, it's not very satisfying. Carson is trying to say something about keeping faith in God in the face of suffering, and trusting that the most seemingly random events are part of his plan, which is a common message in real-world religious writings, but is never very convincing in fiction, where "God" is another word for "the author." There's a choice that faces any author of secondary-world fantasy who wants to feature religion as an element of the setting: are the gods of this world visible and tangible beings who interact with humans and intervene in history to such an extent as to make their presence a demonstrable fact? Or are they as remote and inaccessible as in the real world, so that reasonable people could (and do) conclude that they do not exist? Fire and Thorns either can't make up its mind which of these paths to follow, or is attempting to compromise between them, and the result is unfortunately muddled.

In general, the religious aspect of Carson's worldbuilding is a bit half-baked. Elisa accepts without question that God exists, that he put the Godstone in her navel, that he has some sort of special plan in mind that includes her, and that this plan has to do with the war against Invierne. She has doubts every so often, but they are fleeting and shallow; she may wonder bitterly whether God is listening when she prays, or why he doesn't help her when she needs it most, but it never occurs to her that God might not exist, or that God might (for example) be female, or be more than one entity. Anything other than the monotheism she has been raised with is apparently beyond her power to imagine. More disturbingly, it never occurs to Elisa, or anyone else, that there's something strange about an omnipotent God taking sides in a human war.

This certainty is hard to justify. The Godstones, which only appear once in a hundred years, are the only tangible evidence that Elisa's religion is any more indisputable than the religions of the real world. But although they are obviously supernatural, they don't work all that well as a proof of God's existence, and they say nothing in particular about his nature. It should be possible to come up with an explanation for the Godstones that doesn't invoke God at all, although it seems that nobody has. Despite this, all of the characters take for granted that the Godstones are indeed God's work. There don't appear to be any atheists in Elisa's world, or any other religions (although there are doctrinal differences between groups, much like those between Christian denominations in the real world). Given the ambiguous nature of the Godstones, it's hard to see why.

To Carson's credit, at least some of the muddle comes from a desire to depict Elisa as being in control of her fate. Her character arc is defined by a gradual increase in assertiveness and power: she starts out by passively dreading the approach of a divine test which she expects to fail, and feeling that she has no choice in anything more significant than what she eats for dinner. As she encounters strange and often frightening situations, she adapts quickly and grows in courage and strength, gaining a new perspective on herself and her circumstances that makes her realise both how privileged she has always been and how much control she actually has over her life. Elisa's growth is the best-realised aspect of Fire and Thorns, and the best reason to keep reading through the rather stifling self-pity of the early chapters.

Sadly, the supporting cast are not so well-realised, with most of them no more than vehicles for plot developments or exposition; and apart from the religious elements, there's nothing very original about the setting. Most disappointing of all are the Inviernos. They make for convincingly menacing villains, but that's all; their entire purpose is to serve as a threat against which Elisa can protect her people. Admittedly, we only ever see them through Elisa's eyes, but even so, it is unnerving how little development they get, given that they are not only her enemies but (apparently) God's enemies as well. How could such a situation come about? There could be a very interesting story in that, but you'll find no more than oblique hints of it in the pages of Fire and Thorns.

At its heart, embodied in Elisa's troubled relationship with her Godstone and the destiny it represents, lies the question: how can we reconcile the omnipotence of God with the free will of humans? This is a dilemma which philosophers and theologians have wrestled with for centuries, so it's not really surprising that Carson's answers aren't completely satisfying. Still, her engagement with the problem is just deep enough to be tantalising, but just shallow enough to be frustrating. There are ideas here that could be developed and explored as part of the background to a fascinating novel about fate and foreknowledge and responsibility in a world only slightly more magical than our own, but Fire and Thorns is not that novel. As a coming of age story, Fire and Thorns is decent; as an adventure, it's entertaining. As anything more, it sadly falls short.

Katherine Farmar is a writer based in Dublin, Ireland. She blogs about the arts at Pansies and Nettles.