Carlyle was a friend of Hyuuga when he was still with the Knights of the Silver Tree. He was born into a family of knights and trained from a young age. He was thought to be the one to earn the "Holy Knight" title but Hyuuga got it instead. He died in the Tower of Dreaming Souls near Thunder Village because he inserted an Artifact chip (similar to the one Mathias has) on his neck to receive powers, but could not control them. He got possessed by Thanatos and his soul left him, while his body stayed at the Tower possessed by Thanatos. His soul became a shining butterfly, which throughout the series followed Hyuuga. Angelique noticed the butterfly when she first met Hyuuga, following it into the forest where the former knight was. In Season 2, at the end of episode 4, the butterfly disappears into the sky, meaning that his soul had ascended into heaven and he was now at peace.
Carlyle has light maroon hair. He is always seen in his uniform.