Who is Yagharek from Perdido Street Station and what is their importance?

Yagharek is the avian-human Garuda creature who comes to Isaac for help to restore his wings and his flight. We never learn the exact reason for his missing wings, but he does make an oblique reference to his "crime" with the implication that removal of his wings was a form of punishment. Yagharek has a birdlike beak and a deformed spine that is covered with lesions from rubbing against the apparatus. He gives Isaac a pouch of gold coins in advance for his scientific work to figure out how to replace his wings.