OVA
Description
Fay D. Flourite (also spelled Fai D. Fluorite or Fai D. Flowright) is a central figure with a complex background. Born Yuui, he was one of twin princes in Valeria Country, where twin births were considered a catastrophic omen blamed for widespread misfortune. Their mother died by suicide, followed shortly by their father. The twins were imprisoned separately in a magically suppressed tower without time, Yuui at the base and his brother Fai at the top. The Valerian king later executed the entire population before dying by suicide, leaving the twins as sole survivors. Fei Wong Reed appeared, offering freedom to one twin; the real Fai chose to save Yuui, resulting in Fai's death. Fei Wong manipulated Yuui's memories to believe he sacrificed his brother for survival, then imposed two curses: one compelling him to kill stronger magicians, the other obscured from his memory.

Rescued by King Ashura of Celes Country, Yuui adopted his deceased twin's name, becoming "Fai". Ashura bestowed the surname "Flourite" (after the mineral fluorite) and the honorific "D" denoting Celes's highest magician rank. He placed a phoenix-shaped tattoo seal on Fai's back to suppress his growing magic, warning of severe consequences for using magic without it. Fai received two of Princess Sakura's feathers: one created an artificial being named Chii (modeled after his mother), the other was reserved. When Ashura transformed into a murderous entity due to magic corruption, Fai refused their prior death-pact, instead sealing Ashura in eternal sleep. Fearing Ashura's awakening, Fai fled to the Dimensional Witch Yūko Ichihara. Unable to pay the price to never return to Celes, he joined Syaoran's group to traverse dimensions, relinquishing his tattoo seal as payment for the travel-creature Mokona, leaving him unwilling to use magic unless absolutely necessary.

During the Tokyo Revelations arc, Fai suffered significant trauma. Attempting to reseal the unstable "heart" within Clone Syaoran's right eye failed. The Clone, acting on instinct, consumed Fai's left eye to steal half his magic, severely diminishing his power and plunging Fai into near-fatal shock. To save him, Mokona contacted Yūko; Kurogane wished for intervention. Fai was turned into a vampire using blood from Kamui, binding his survival to regularly drinking Kurogane's blood. This forced emotional withdrawal; he stopped using nicknames like "Kuro-rin" for Kurogane to distance himself, fearing attachment. Physically, he wears an eyepatch, ages slowly, heals faster, but suffers constant blood cravings specific to Kurogane.

Fai's personality presents layers of deception masking trauma. He maintains a cheerful, teasing facade to conceal profound guilt and self-loathing, stemming from Ashura's advice that his smile could heal others, contrasting his destructive magic. He is emotionally distant, viewing his life as expendable and fighting only to protect others. Despite this, he grows attached to Syaoran, Sakura, and Kurogane, repeatedly breaking vows to use magic for their safety. His reliance on evasion and weapons over magic highlights his escapism and fear of his power. Post-vampirism, his demeanor turned cold and solemn, though he later reverted to earlier mannerisms after resolving his curses.

Later developments reveal Fei Wong tampered with Fai's past; Syaoran's time distortion potentially erased his original twin existence. Fai sacrificed his remaining magic to restore Kurogane's severed arm via Yūko. He later regained his left eye after Fei Wong killed Clone Syaoran. Post-Fei Wong's defeat, Fai, Kurogane, and Mokona accompany the original Syaoran on perpetual dimensional travels. His core traits—protective instinct, masked pain, and reliance on Kurogane—endure.