The Sehret Chronicles: The Merchant's Son

Sheth Terrem is the son of traveling merchants, making one last stop in the bordertown of Lans before they return home with their newly-acquired merchandise. But then tragedy strikes, and a simple promise sends Sheth to live with a man he's barely met, who seems as though the last thing he wants is an orphaned teenager to foster. Sern Jesyn expected to look after the boy for a day, perhaps a week or two at the most.
With unrest in the streets and among those who walk them, living alone is trial enough. Now that their time together has been termed indefinite, and long-suppressed memories come back to haunt him, he shudders at the thought of following through on his word. But what neither of them knows is that their trouble did not end with the riot. Rather, it lives on in the surviving assailants, and in a boy called Siran, who finds keeping his nose out of his older brother's business both difficult and increasingly dangerous.