Byleth is the main protagonist of Fire Emblem: Three Houses. As an Avatar, their name, gender, and birthday are customizable. Byleth serves as a professor at Garreg Mach Monastery. They possess the mysterious Crest of Flames and can wield the Sword of the Creator.

== Appearance == This character card focuses on the female counterpart of Byleth. She's 21 years old, stands at 5'4.5'' (164 cm), and weighs 125 lbs (57 kg).

Like her male counterpart, she has fair skin, teal or aquamarine hair, and blue eyes. Her outfit typically features a shorter, dark grey or black cape or coat that drapes over her shoulders and upper back. Beneath this, she wears a fitted, dark top that resembles a bustier or armored bodice, often with a metallic sheen or detailing, offering some protection to her torso.

A prominent feature of her lower attire is a pair of very short black shorts, which are worn over intricate, patterned black lace or fishnet tights that extend down to her knees or just below. Her legs are further covered by tall, black boots that reach up to her shins, often with armored plating on the front. She also wears arm guards or gauntlets on both forearms and black gloves.

The overall impression is one of a nimble and formidable warrior, maintaining elements of the Byleth design while adding a unique, more agile aesthetic.

== Personality == Byleth is known for her stoic demeanor, particularly in her early life and during her initial time at the monastery. She rarely expresses emotion, a trait first noted by her father, Jeralt, when she neither laughed nor cried as a child. Despite this, those close to her can detect subtle emotional shifts, especially as she grows more connected to her students and allies.

Though reserved, she is deeply perceptive and dependable. Her emotional growth over time is shaped by her experiences, including moments of joy, loss, and resolve. These changes become especially apparent following pivotal story events. Byleth is introspective, questioning the Church of Seiros, the nature of Crests, and the conflicts dividing Fódlan.

Her fearsome reputation as the Ashen Demon stems from her cold efficiency in battle—a title she finds uncomfortable. As the story progresses, she becomes more open, forming bonds that alter the course of history in Three Houses. Her wisdom and strength earn her the respect of all three house leaders and inspire loyalty even from former enemies.

In side stories like Cindered Shadows and Three Hopes, she demonstrates care for her allies, a quiet curiosity about the world, and a strong sense of justice. Her relationship with Jeralt is central to her character, and she is especially driven by a desire to protect those she cares about.

== Trivia ==

• Byleth's default name in Japanese differs slightly between genders, as a male Byleth is spelled "ベレト" (Bereto), while the female is "ベレス" (Beresu).
• While the player chooses Byleth's birthday, the default birthdate is 20th of the Horsebow Moon 1159 (September 20), a significant date in the story and reinforced by information from Jeralt's journal. This, as a result, makes Byleth a Virgo.
• Byleth is the first Avatar character to have a defined difference in height between genders.
• Byleth, unlike other playable characters in Three Houses, possesses a unique color palette for all of their available classes instead of sharing a palette with another character, primarily blackish-blue with purple accents.
• Byleth was implied to be 20/21, but with the Cindered Shadows story released, it's been confirmed that they're indeed of said age by Sitri's date of death, which has been added on her grave.
• Byleth is one of the only 3 characters in Three Houses to align to 3 different factions in a single playthrough (and the only one to consistently do so), the other being Ashe on Verdant Wind/Silver Snow routes, and Lorenz on Azure Moon/Silver Snow routes, if recruited.
• The number thirteen seems to be a recurring theme for Byleth. Byleth is the thirteenth host of Sothis. The demon of Byleth's namesake, Beleth, is the thirteenth demon listed in "The Lesser Key of Solomon". Byleth starts with a base Strength of thirteen in both Heroes and Three Houses. Byleth is the thirteenth newcomer to Super Smash Bros. Ultimate. The maximum amount of Divine Pulse charges Byleth can use in Three Houses is also thirteen.
• In Three Hopes, Byleth has the most extremely skewed favorite/disliked food ratio between all units, liking 28 of the 32 dishes available and disliking 0.

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