Flat Escardos, eldest son of the coastal Mediterranean magus lineage, the Escardos, manifested extraordinary magical talents from childhood. He translated ancient family magecraft incomprehensible even to the family head and devised new spells by synthesizing past techniques. This immense ability rendered him unnatural and dangerous in the eyes of his family, leading his parents to attempt his murder multiple times. Flat survived these attempts due to his unique perception of an unspecified presence called "it," invisible to others. Realizing others perceived a different world caused him significant distress. Ultimately exiled before age ten, his parents sent him to the Clock Tower.

There, his exceptional magecraft talent became undeniable. Flat demonstrated rare control over magic circuits, absorbed complex magical information with near-perfect academic results, and achieved outstanding performance. Yet his idiosyncratic temperament, absence of conventional magus traits, and disruptive actions—like altering professors' magical formulas during lectures—resulted in widespread rejection. Faculty struggled to manage his potential, and he faced repeated expulsion threats due to administrative issues. His situation stabilized when Rocco Belfeban, head of Summoning, facilitated his transfer to Lord El-Melloi II's classroom. During their first meeting, Flat used magecraft to force a smile, which El-Melloi II instantly recognized as artificial, prompting Flat's first genuine smile in years.

Within the El-Melloi Classroom, Flat ranked among the top students alongside Svin Glascheit. Despite his academic prowess, his personality prevented graduation for nearly a decade. He forged a notable camaraderie with Svin, nicknaming him "Le Chien" (The Dog) due to Svin's Beast Magecraft, though Svin disliked the name. Flat is defined by a "superabundance of curiosity," sharply contrasting with his poor grasp of history, logic, and strategy. Characterized by whimsy and a lack of common sense, he prioritizes impulsive interests over magus conventions, expressing fervent enthusiasm for seeking the Holy Grail and citing figures like Hitler and Qin Shi Huang as motivation.

His obsessive curiosity about the Grail led him to participate in the Holy Grail War in Snowfield as False Berserker (Jack the Ripper)'s Master. He employed a toy knife for the summoning ritual, intervened in battles by teleporting his Servant away from True Archer's attacks, and manipulated True Archer's magical energy via Command Spells despite not being its Master. He further demonstrated unpredictability by infiltrating a secret meeting concerning the False Holy Grail War.

Flat conceals his full name to evade curses. His magical intuition diverges from typical magi, emphasizing exploration over tradition. Incidental encounters mark his background: sneaking onto Van-Fem's casino boat as a child and being permitted to stay after demonstrating magecraft, and interacting with Ayaka Sajyou after deciphering the Voynich manuscript, which inadvertently caused interdimensional plants to manifest during a botany class.