The Color Prince, also known as the Omnichrome, and later known by his followers as the White King, was originally a noble named Koios White Oak, but has since been burned so horribly that he had to use Luxin to reconstruct a body for him to live in. He is (or rather used to be,) the brother of Karris.
Just before the War Of The Prisms, Dazen Guile and Karris White Oak planned to elope, against the wishes of both of their sets of parents, as well as Karris' brothers. Rissum White Oak, father of Karris and her brothers, learned of the plan and informed her brothers, who set a trap for Dazen. When Dazen arrived at the White Oak estate, Karris was not there, but a maid lied and said that Karris was inside. As soon as Dazen entered, the seven brothers attacked him, intending to kill him for the imagined shame he had brought to their family. Dazen fought back and drafted Black Luxin. He killed six of the brothers, gaining the ability to draft their colors, and thought that Koios was dead as well after a burning wall fell on top of him. How Koios managed to survive this is currently unknown.