Cast in Shadow by Michelle Sagara
Kaylin serves in the Hawks, a sort of police department, in Elantra. She's summoned to the Hawklord's office one morning to receive an assignment and two partners. One of the partners is an old friend who betrayed her seven years before and she hasn't forgiven him. (Her first instinct is to attack him.) The other is a Dragon.
The assignment is to find out who is killing children in the fief (borderland towns that are rather lawless) of Nightshade, just like children were killed seven years before, when strange markings appeared on Kaylin's arms and legs.
There are bird-people (Aerians), lion-people (Leontines), people with mind-reading tentacles (Tha'alani), mages, elves (Barrani), and, yes, dragons. Many of these creatures live happily together in Elantra and work together in the Hawks.
This book feels like it should be a second book when it begins. The reader is dropped right into the middle of things, with little explanation (why Kaylin hates Severn isn't told until almost 3/4 of the way through). Eventually things begin to make more sense, as Kaylin stumbles deeper into the mystery, but I was frustrated at many points in the first half of the book.
When the action started picking up in the middle, I became less frustrated. Except I wanted more explanations than people were giving to Kaylin.
Kaylin is a very imperfect protagonist: she's always late; she's impulsive; she has no desire to learn anything she doesn't consider useful. These are rare traits in female protagonists, and I applaud Sagara for giving them to Kaylin. I couldn't really identify with her (I'm punctual to a fault, and I like learning things), which may have put me off her character a bit. Sometimes I wanted to shake Kaylin for being a stubborn brat; sometimes I wanted to shake the people who weren't telling her everything she needed to know to make good decisions.
The ending was interesting and unexpected; I didn't understand Nightshade's explanation of why he didn't kill the villain. Sometimes I need things spelled out a lot more than authors give me. The romance felt a bit shoehorned in (it was published by a Harlequin imprint), but it was believable.
I liked this book well enough; if you like fantasy with emperors and dragons and magic (and old magic), you might enjoy it.