Lythlet and her best (really only) friend Desil are both slumdogs. They work their asses off, but they can never seem to make more than ends meet. Despite Lythlet's striking intellect and prowess as a bookkeeper, she can never seem to get ahead. She can't get hired by anyone except for abusive men who use her skills to embezzle and cheat, and when she leaves her latest job, she finds herself facing the real possibility of never getting out of her current lot in life.
A major reason for that, though, is a massive debt Desil has found himself in, one in which Lythlet feels obliged to help him resolve. He owes a lot of money to a loan shark, and while the principal isn't all that much, the interest is outrageous and, being the wiz with numbers Lythlet is, she is only too aware of just how unlikely it is for Desil to get out from under his debt.
When Desil learns that Lythlet has left her latest job, he proposes to her that they consider becoming conquessors. These are arena fighters who go up against monsters for the chance to win large sums of money. While Desil has a reputation as a brawler in man-to-man competitions, it has been a long time since he fought and he has since sworn off hurting other people. Instead, he dove into religion to help find guidance. Despite this religious conviction, he seems to be okay with fighting these "sun-cursed" monsters. He's just worried that Lythlet might get hurt. While he isn't sure the pair can go through all twelve challenges, he seems confident that winning just a few should earn them enough money to get out from under their debt.
At first, Match-master Dothilos is only interested in Desil because of his reputation and sees Lythlet as a liability to the young fighter, but when they have their first match, he immediately recognizes Lythlet's gift is in her mind as she directs her friend to quickly vanquish their initial challenge.
The Serpent Called Mercy takes place over twelve months, with each arena challenge putting the pair in a new and dangerous situation. During that time, Lythlet and Desil's popularity will grow, and with it the rewards from successful fights. Meanwhile, Dothilos sees potential in Lythlet for something more than just Desil's arena companion.
Over the course of this book, the fighting pair will have their relationship challenged, especially as Dothilos works to drive a wedge between their lifelong friendship. Can Lythlet achieve her ultimate goal of leaving the slums with Desil attached to her hip? Can he do what is necessary to get in good with the people who can help her rise above her humble beginnings? Can she bear the idea of leaving him behind or will she find a way to haul him up with her?
The Serpent Called Mercy has a lot of moving pieces, and while the primary plot is about Lythlet and Desil's series of fights against a variety of creatures, there is political intrigue and seedy underbelly dealings circling all of their efforts. The problem is, it seems like the core of the book (that of their arena fights) seems to hurt a bit by working these other elements into the story. As a result, there are some fights that the pair face that are covered in only a paragraph or two, making a chunk of the twelve challenges all but a footnote. So while the book promises fights with insane creatures, it doesn't quite deliver on the number of them the reader might be hoping for. On top of that, the other elements are good and are necessary for the overall story, but when those plot points are advancing, it almost feels like filler until the next fight.
All that being said, the three main characters, Lythlet, Desil and Dothilos are well done. Lythlet is a bit of a Mary Sue, but not to the point where I found her annoying. She does seem to always have the right answer, but they don't feel as unearned as some books I've read. At least when she comes up with an answer, there is a fairly plausible reason for it. She does seem to have exactly the right set of skills necessary to solve whatever problem is facing her though, and that includes the bigger political plots that suddenly surround her.
One aspect of her character that I actually liked was that, at times, her dialogue felt a bit too formal or stiff. At first I was put off by this, but her character is one that has struggled with a speech impediment and spent a lot of time in books before really talking to others, so much so that other characters even point out that she says words incorrectly because she's only ever read them. As a result, her grandiose comments feel more correct than they would from other characters, so I applaud Lau for this bit of characterization.
The Serpent Called Mercy is the story of two lifelong friends who rely on each other, but also have that friendship tested in the harshest of ways. This relationship is one of the book's successes. Where I wish it would do better is either in focusing more on the monster-fighting aspect or more on the world-building. That being said, there are enough hints about the magic system, the gods, and other countries that I hope The Serpent Called Mercy is just a springboard for Lau to explore this world more, even if Lythlet and Desil aren't the main characters in those future stories.
