There are three point of view characters in The Sun Blessed Prince. Two, are discussed on the jacket cover: Elician and Cat. The third is somewhat of a surprise. Her name is Fenlia (Fen) and she is Elician’s younger sister. Fen is fourteen and she reaches sixteen by the end of the book. She’s a major point of view and perspective through the narrative, and it is understandable to ask: why do we spend so much time in the mind of a child when it’s an adult fantasy book?
The answer might not be very satisfying to everyone, but it lays at the root of what Fen does for the story itself.
Fen is a child because she is a representation of the black and white thinking that children have. There is a judgment call being made with Fen, one that says: look at her behavior, look at her actions and her words, and see that they are childish. Fen is racist. She’s bigoted. She is judgmental. She says things without thinking of the consequences of those actions, and she makes claims on different topics specifically because they suit her and her interests first and foremost. She is mean at times, and she doesn’t necessarily intend to be mean. But all of these things are considered from the get go: childish behaviors that are inappropriate.
Many stories with young main characters show that child growing up with a great deal of empathy or focus on that character on their own without input from the outside world. Here, we know full well what the outside world thinks of her actions - she is judged accordingly by our other two POV characters and their fellows. Her actions are never excused, instead: they are called out. Again, and again, and again.
When she is racist or bigoted, her behavior is ridiculed. She is informed, firmly, that it is inappropriate. She needs to grow up, she needs to get over these beliefs. They are inappropriate, they are wrong.
Fen serves as an embodiment of what happens when people in general (regardless of age) are too closed off in their mindset. I could well have made her an adult acting the same way that she does, but by framing her as a child it cements home just how childish her words are. And, crucially, it offers a gentle opening to say: even if someone does act this way they do have the ability to grow.
Throughout the book, we do see Fen’s reasons for why she feels the way she feels. We are shown her fears, her prejudices, the roots of her concerns. These could well have followed her into adulthood, and we do see the effect of adults that act in the way she does. However, when these behaviors are wrapped in a body of a child there is a sense and a hope that with proper guidance that child can overcome her flaws. It is a grace not often given to adults who are often expected to be set in their ways.
Judgmental adults permeate society. But their actions and their beliefs are childish. I don’t mean this in a mocking way, and by no means intend to diminish the hurt their words cause. Instead, I mean to draw attention to how the actual thought process of these judgments are conceived. Black and white thinking, total right or wrong fallacies, and emotionally driven thoughts which override logic make up the crux of these adults’ thought processes. They can’t accept an alternative to their point of view because they are stubbornly refusing to listen to another point of view. They don’t want to hear it - they are covering their ears like a kid and stamping their foot because anything except for the reality they have is wrong.
Fen acts as the physical embodiment of this mentality. She is a child because she thinks and acts like a child, and because the other characters in our world are consistently struggling to fight against a very pervasive set of beliefs that is increasingly difficult to overcome.
As she gets older, though, and as she is introduced to more experiences and treated with patience as she is guided by peers and mentors: her thinking begins to change. She grows towards adulthood at the same pace as she releases her bigotry. She becomes a strong character in her own right by abandoning some of her rage and actually listening.

It is a metaphor.
A very long and extended metaphor, but one that encapsulates everything her character is meant to do.
She is not just a child growing up and having a coming of age story, she is bigotry and judgment, and she is experiencing that which overcomes such things. She reaches her maturity only when she is able to let some of that go. She is a societal statement, and her arc is one that is meant to show how individuals dealing with those who are judgmental or bigoted can be handled.
Fen is not the only child in the story who acts this way. There is another child character introduced late in the book: Gillage, and he too is cruel and hateful. (In retrospect, I should state I have nothing against children as children, but in this book: the children are children because they are cruel and need to grow up.) The thoughts and actions that Fen and Gillage display are not a typical coming of age story meant for a young adult audience.
These are deeply reflective on the status of childhood and the metaphor of childish representations. Young readers may find comfort in reading about Fen, but her arc is one that is more reflective from an adult point of view. She is the embodiment of childhood mistakes, fears, and misunderstandings. She is the archetype of all the bad memories and cringing wincing “oh no I did that too when I was young and didn’t know better.” Her purpose is to make an adult reader sit back and actively reflect on times in their lives when they too said or did something unintentionally cruel, or from a place of discomfort.
She may take up a large portion of the book, but her presence there is one that exemplifies the very thing that our other two main characters must overcome. For Elician and Cat to stop the war that is tearing their countries apart, they must first find a way to breach the prejudice that is deeply embedded in their societies.
Converting Fen, healing Fen, getting Fen to a place of acceptance, thus is a way of showing that society itself can also be healed. The childish black and white thinking of the past can be overcome, and as a society: they can all grow to a better tomorrow.
She is annoying. She is frustrating. But her presence there is not because the book is dedicated to young audiences, but rather - for an adult audience to reflect on how even as adults we too can be childish, and how if we speak or say things like Fen, perhaps we too need to do better and learn to grow up.