Byleth

Lore

According to legend, Byleth bears the title “the Mighty and Terrible King”; some sources go further, calling him the “King of Hell,” and give him the ordinal number 13.

Visually, his appearance is always both ceremonial and intimidating. Before the king himself becomes visible to the conjurer, the air fills with blaring trumpet tones and the music of many instruments; Jacques Collin de Plancy, in the Dictionnaire Infernal, writes that the procession is performed by cats blowing horns, creating a frighteningly surreal atmosphere. After this sonic prologue, Byleth emerges as a majestic, ferocious king on a pale horse reminiscent of the fourth Horseman of the Apocalypse; his face is furious and terrifying, and later folklore often ascribes feline traits to him—vertical pupils, glowing eyes, or even a cat’s head on a human body.

Legend holds that Byleth is a fallen Power, once an angel of high rank whose original function was to preserve the borders between worlds and protect humankind from evil spirits. His fall is tied to Lucifer’s revolt in Heaven. Byleth still hopes to reclaim a celestial throne, though, to be realistic, that ambition is unlikely ever to be fulfilled. His intellect surpasses the human: he is famed as the “Spirit of Mathematics” and, according to lore, taught Ham, Noah’s son, the science of numbers after the Flood, giving humanity a rational tool for shaping the world.

In behavior he blends rage with cold calculation; his aggressive entrance tests the operator’s courage, and he despises weakness. He speaks weightily and in vivid imagery, often threatening until ritually subdued, and he insists on being addressed as a great king, taking offense easily if protocol lapses.