- "But, if a crop should fail or a war be lost, the Magisters will slit the Prince's throat and choose another."
- ―Jorah Mormont
The Prince supposedly holds the powers of trade, justice, and war, and on every new year he must deflower the Maid of the Field and the Maid of the Sea to bring good fortune to the city. However, the title is mostly ceremonial and should a crop fail or a war be lost, the Magisters slit the Prince's throat and choose a new Prince.
In the books
In the A Song of Ice and Fire novels, the Prince of Pentos has a mostly ceremonial function and presides over balls and feasts. He rides through the city in a palanquin of ivory and gold, with three heralds before him carrying the Golden Scales of Trade, the Iron Sword of War, and the Silver Scourge of Justice.
It appears that the chosen Prince has no choice if selected. The leader of the Windblown mercenary company, the Tattered Prince, when he was twenty-three, was chosen almost immediately after the Magisters had beheaded the previous Prince. Instead of taking the mantle, the young man fled the city never to return.