Redwing

Rowan is the sole survivor when his entire family is struck down by the plague. Alone and grief-stricken, Rowan ekes out a living by playing music on his button box in the small towns and villages of Prosper. He lives and travels in his family's old caravan, half starved and in despair. One day, he finds he has competition: a young man playing a violin. Rather than make an adversary, Rowan suggests they travel and play together, but he regrets his offer when he finds out that Samik is from the Tarzine Lands, beyond the volcanoes, and is being pursued by a vengeful warlord.
And that's not all. Samik also claims to have the Sight-and what he sees (and hears) is Rowan's dead sister, Ettie. As they travel from town to town, they form an uneasy alliance, which gradually evolves into a friendship that will be tested to its limits when Samik is captured.