Claude Lian was born in Braavos, a Free City in Essos. His mother was a chaste and dutiful Red Priestess of R'hllor. She met his father at a town celebration, and was swept off her feat by the traveling merchant. He charmed her and she forgot her vows for that one night. It was all he needed, and by the time she realised she was with child, he was already well out of her life. Even though the Red Priesthood doesn't require celibacy, Claude's mother felt that Claude himself was a constant reminder that she had broken her vows to her God. She wasn't cruel, and her sense of duty and charity made it impossible for her to neglect Claude of his basic needs. She didn't give him the love of a Mother though, she looked at him as one might a scar, he was a living embodiment of her mistake and failure.
The rest of the Priesthood pitied the boy. They came in to offer the additional care that a child needed outside of food and water. He was more raised by them than his mother, and once she realized she had an 'out,' she took it. Claude's mother became more secluded from the Priesthood in her own internal torment, and thus, away from her own son. It only made sense that as the boy came of age, he began to learn the ways of the Red Priests and of R'hllor. The god R'hllor had a few main tenants, but a god who embraced so many good ideals allowed for some room for interpretation. Claude's personal experiences shaped him so that Light and Fire were the essence of Life. His philosophy was enforced by his gifts, as flashes of insight and healing came naturally to him. Where some Red Priests would stare into bonfires for wisdom, Claude could stare into a man's eyes to see the fire inside for the same; Where Red Priests would light larger fires to appease R'hllor, Claude would live his life to the fullest, making the most of R'hllor's gift to all living creatures. Life was to be lived bright, even if the brightest candles burn out the fastest.
The Red Priests accepted Claude, but his Mother still saw him as a sign to her own fall from grace. She returned to being a figure in the Priesthood, denouncing Claude's interpretations of their great God, if only to spite him. Claude took his leave of the local Chapter, if only because he felt wrong to quarrel with his own mother. He left in the Priesthood's good graces, heading west to Westeros to spread the word of R'hllor, to help others live their lives to the fullest and brightest, to help remove the guilt of regrets, to brighten the shadows that threaten the world.