Katherine Applegate wrote books that defined my childhood, books that rank among my favorite to this day. So, be warned that my opinion comes with a strong positive bias.
What I love about Applegate's writing is how she knows her audience, and she doesn't shy away from them. Her writing voice is simple and straight-forward; she uses simple words and short paragraphs that are easy to follow and comprehend. From my experience, she tends to focus on YA and MG books, with an audience targeting middle and high schoolers for the most part.
It is her themes that are for adults. It is the underlying starkness of the pain and evil of the real world that earns my respect.
Endling is, in part, what I expected of Applegate. Simple enough for a middle-school child, but with hopeful themes any adult can appreciate. She uses many "standard" fantasy templates- the exiled/deposed heir, a magical sword, a rogue with a heart of gold, magic and betrayal and long quests through a fantastical land- but she also brings new themes. It is a bit relaxing for a lover of fantasy to not have to see rehashed Elves, Dwarves, Orcs, and Wizards identical in all but name. She creates new races, with their own powers and realms and backstories that don't readily trace back to the fantasy tropes. There is magic, but it is used both by powerful wizards in towers and common men replacing their worn-out shoes.
And while the fantasy land is beautiful to look at, its characters so whimsical you sometimes expect them to rhyme, Applegate, in her usual style, doesn't hide the dark side. **Minor spoiler, but in the first few chapters, our hero, already part of a dying species, must see, in brutal, stark clarity, her whole family, her entire species as she knows it, killed without mercy or care. She sees the bodies, she smells the blood, and it deeply upsets her. When I read Applegate in middle school, this brutality hidden in plain sight with simple words is what I loved the most. She doesn't talk down, or hide, or belittle her audience. She trusts her readers, though young, are mature enough to handle what she offers.
Her characters are young as well- the oldest character with a given age being about 14, and the youngest being the equivalent of 8. And yet, in their own way, they are all strong, and brave, and courageous, and prove highly positive role models to live up to. The youngest, a little mouselike creature named Tobble, always being praised for his heroism and bravery, even though he is usually too small to fight, too weak to help, but he is always, always the first to offer.
Our heroine, Byx, I especially adored. Where we have her friend Khara as the woman-warrior, strong in battle and brave and honorable, Byx is small, and weak, and humble. Even though Byx is in several battles in the book, her instinct is not to harm. And she is not the meek hero who slowly becomes a strong warrior. Byx's strength is her honesty, which she uses time and again to save herself and her friends.
In truth lies strength.
Overall, it's a book I highly recommend to adults both young and middle-grade. And I am thrilled to see she has more books planned in the series, and she will not end this in a major cliffhanger like she ended EVERY OTHER SERIES I HAVE READ FROM HER.