Who is Percival and Isabelle Derby from Copper Sun and what is their importance?

Percival Derby is the owner of Derbyshire Farms and all the slaves that go with it. Throughout the novel, Mr. Derby is seen as a controlling man who beats his slaves into submission, but he never goes above or beyond what is expected of slave owners at the time. His first wife passed away giving birth to their son, Clay, and Mr. Derby is enamored with his new younger wife, Isabelle. When Mr. Derby finds out that the child Isabelle has just given birth to has been fathered by a slave, he snaps and shoots Isabelle's lover, Noah, and their newborn child. At the end of the novel, Percival Derby has been poisoned to death by Teenie after he gets rid of her only child, Tidbit.

Isabelle Derby is the second wife of Mr. Percival Derby, the plantation owner. She is eighteen-years-old, much younger than Mr. Derby, and loathed by Clay. Mrs. Derby is a kind woman who treats her slaves with respect. This kind treatment is a result of her love affair with Noah, which produced a child. When the baby is born, Isabelle immediately knows that Mr. Derby will kill her, so she begs the slave girls to help her hide the baby. When the plan fails Mr. Derby shoots both Noah and the newborn baby point blank in the head.