This is book number 1 in the Empire of Storms series.
In a fracturing empire spread across savage seas, two young people from different cultures find common purpose.
A nameless girl is the lone survivor when her village is massacred by biomancers, mystical servants of the emperor. Named after her lost village, Bleak Hope is secretly trained by a master Vinchen warrior as an instrument of vengeance.
A boy becomes an orphan on the squalid streets of New Laven and is adopted by one of the most notorious women of the criminal underworld, given the name Red, and trained as a thief and con artist.
When a ganglord named Deadface Drem strikes a bargain with the biomancers to consolidate and rule all the slums of New Laven, the worlds of Hope and Red come crashing together, and their unlikely alliance takes them further than either could have dreamed possible.