Foundryside

Robert Jackson Bennett has created a world, Tevanne, with elements of steampunk, dominated by several large and powerful commercial houses that control everything through mechanized magic. Using a process called "scriving,"  they make objects think they are something other than they are, i.e., it can alter the reality of things. Heavy things think they are light, stationary things think they are falling from great heights. But what if you scrived a human being. Could you make them think they are fearless, invincible, brilliant? Of course such a thing would be strictly forbidden if there were actually any laws, but such efforts have been secretly ongoing for decades in laboratories on remote colonies. Slaves are used up as experimental subjects and so far no one has succeeded. Or have they? Our protagonist, Sancia Grado, is a scrawny, underfed but extraordinarily accomplished young thief living in the slums that surround the great commercial houses. She has been hired by her fence to steal something that will give her enough money to get the metal plate out of her head that causes her searing pain in response to touch, light, sound--in fact, almost any sensation. But it also allows her to hear scrived devices murmuring and to understand everything about them when she touches them. Hence her success as a thief. She can find every nook, cranny, or hole through which to slip, and can hear the presence of anyone coming through touching a floor, a wall...
But things go awry and she accidentally starts a huge fire at the docks in the process of the theft. And when she opens the small box she stole--strictly against orders--she finds it contains an elaborate key that can talk to her. She names him Clef. But Clef was probably made by an ancient race of magicians who had achieved nearly god-like powers, and people are willing to kill to own him. So Sancia is on the run not only from the head of Tevanne's new security force but also from someone who wants to up-end the balance of power in Foundryside. This is an elaborate and well-crafted world with empathy-worthy characters and an elaborate and compelling plot. This is supposedly the opener for a new series. Bennett has also written the "Divine Cities" trilogy and several stand alone novels, I just started the first book in his previous trilogy, City of Stairs.