Percival Darkmore was the invincible Black Knight during the age of King Arthur. While on his travels, he found Charger, one the Z-Sprites The evil Emperor Mordred captured Percival and Charger and imprisoned them in the Shadow Dimension. There, Mordred brainwashed Percival and Charger and made them his pawns. When he learned that Nimue was creating her own Rangers, Mordred released Percival and used Charger's powers to turn him into the Black Knight Ranger, keeper of the spirit of the Pegasus. At first the Black Ranger was the Rangers' worst enemy, but when Percival realized that Mordred had brainwashed him, the Black Ranger turned on his master.