Satrap Cosgo, often simply referred to as the Satrap, is the ruler of Jamaillia.
Cosgo is extremely self-centered, often condescending, and remarkably entitled. He is fond of various intoxicants, including wine and pleasure herbs, and indulges in them to great excess, growing petulant when his supplies run low or when he experiences withdrawal symptoms. Despite his youth, he is not healthy; he is prone to coughs and colds, experiences seasickness, and is pale and somewhat soft-bodied.
The Heart Companion Serilla, frustrated with Cosgo's lack of involvement with foreign affairs, attempts to convince him to allow her to visit Bingtown and act in his stead to control the city's simmering politics. The Satrap defies her persuasion and decides to sail to Bingtown himself, despite the fact that a Satrap leaving Jamaillia City for such an extended voyage is practically unheard of. Cosgo is lavishly furnished for his trip by many of his nobles.
When Serilla displeases him during the voyage, Cosgo gives orders for her to be imprisoned and repeatedly raped by their Chalcedean captain. Later, when he falls ill, he releases Serilla in order that she might care for him and his sickened Companion Kekki. Unbeknownst to him, Serilla begins dosing his food with emetics and takes liberties with the comforts provided for Cosgo throughout the rest of the voyage. She also persuades Cosgo to sign a document that grants her the Satrap's full authority to direct matters in Bingtown.
Cosgo attends the Trader's Ball, where Davad Restart introduces Malta Vestrit to him. Cosgo makes advances toward Malta, which she rebuffs. When the ball comes to a close, Cosgo joins Malta and her family in Davad's carriage despite Malta's earlier reaction to him. On the way back to the Vestrit home, the carriage is accosted and Cosgo and Kekki are kidnapped and spirited away to the Rain Wilds, where they are housed secretly in the ruins of Frengong.
When an earthquake strikes, the room where Cosgo is being kept begins to fill with mud, and he is trapped inside. Malta hears Cosgo and Kekki shouting and manages to pry open the door to their chambers, freeing them. Cosgo follows Malta as she leads them through the ruins and back out to the surface.
Cosgo is incensed at being stranded in the Rain Wilds, and his mood does not improve when Malta refuses to act as subserviently as he wishes. He does not deign to assist her in procuring a rowboat, testing its seaworthiness, and fashioning oars with which to paddle downriver. Once afloat, Cosgo struggles to paddle the ship, which results in Malta growing frustrated with him and taking on most paddling duty herself. Cosgo is very uncomfortable during their journey, as he grows sunburned, bug-bitten, and weak from lack of food or water.
As their rowboat approaches the mouth of the Rain Wild River, they encounter a Chalcedean ship. Cosgo presents himself as the Satrap, but the crew and captain ignore him, placing him in a small room. Cosgo demands a bath, which the Chalcedeans provide by drawing up water from the river. Cosgo ignorantly washes himself with it, which causes redness and blistering.