Who is The Yovogan from The Viceroy of Ouidah and what is their importance?

The Yovogan is the Dahomean Minister for the Slave Trade. A tiny octogenarian who dresses in pink finery, he is a useful liaison between Francisco and the King of Dahomey, but the Yovogan dies of poisoning and is replaced by another Yovogan who refuses to admit that a slave trade exists. In the book, the first Yovogan represents the fragility of the relationship between Francisco and the unpredictable king.