The Swan King

The Swan Prince has become the Swan King, as his father has retired with his mother to an extravagant hunting lodge in the mountains. Darthon always knew running a kingdom wouldn't be easy, but he hoped it wouldn't be this stressful. Avis has become an empire of business and is quite civilized, no longer the simple country of farmers and thatch-roof villages his father ruled. Its rapid development is due to distant countries finding its ports valuable as a way of trading with richer countries inland, and the kingdom must now be ruled with diplomacy, no longer impressive jousts, long hunts in early mornings, and villager unrest can not be quelled by burning down houses.
Darthon has some comforts. One of his advisors is the most powerful witch in the kingdom, and she commands a respect Darthon has yet to gain from his people. She is a good witch, but Darthon still fears her. It was a sorcerer very like her who cursed his mother into the shape of a swan. Though she recovered from it, residual magic of the curse seeped deep into her being, and is responsible for Darthon being born...deformed.
That is what they say about his wings. Massive white things, each one fifteen feet long. Too long--they drag on the floor when he walks, and cause him anxiety at night if he sleeps on either of them--a primitive fear of not being able to escape danger.
If they were at least on his back, then Darthon would have been hailed as an angel. But alas, the wings instead replace his arms. Thus, Darthon is regarded as a freak by his relatives, the only ones that know, and must go about his life draped in long, heavy cloaks to conceal his oddity. His wings are clipped and confined by the cloth, and similar to sleeping on them, it has caused him anxiety and panic attacks for most of his life. His only brief reprieve was for a short time in his childhood when he met and played with a street girl, Ilsar. She convinced him to let his feathers grow and tried to teach him to fly. He almost made it--but then Ilsar disappeared. He never heard from her again, and Darthon clipped his feathers and went back to his confining cloaks.
Now, twelve years later, Darthon meets her again in Avis's den of thieves. Captured by the thief king, rendered helpless with his bodyguards lost in the sewer tunnels, Darthon's future looks bleak. But it turns out the thief king's future is even bleaker as Ilsar drops from the ceiling and plunges a dagger into the man's head.
Having claimed the throne of thieves, Ilsar negotiates a peace with Darthon that deeply unnerves him--she, a streetrat, handles dealings better than he, a born and raised prince. And she's much colder than the boisterous, passionate street girl he knew in his childhood.
What happened to Ilsar? What made her disappear? What changed her? What made her so...frightening? And why can't Darthon stop thinking about her?
A swan and a rat could never be together. Can a thief and a king do any better?