Byleth

"I will return here someday my teacher, promise me that you won't forget me."

- Edelgard talking to Byleth

Byleth, is a playable character and the main protagonist in the upcoming Fire Emblem: Three Houses. As an Avatar, their name and gender are chosen by the player. In voiced cutscenes, they are referred to as Teacher.

Profile
Once a part of a mercenary group lead by their father Jeralt, Byleth is offered a position to teach at Garreg Mach Monastery's Officer's Academy after an unexpected incident reveals power within them.

They are offered the position to teach one of the three houses of the Monastery: The Black Eagles, Blue Lions or Golden Deer.

Around this same time they begin to see Sothis, a mysterious girl only they can see, who appears in their mind. As part of training, Byleth at times leads their students into live combat. Swords appear to be their main weapon.

Etymology
Byleth is a variation of Beleth, a king of Hell. Invoked by Ham, Noah's son, he aided in the writing on a book of mathematics.

Trivia

 * Byleth's default name in Japanese differs slightly as a male Byleth is spelled "ベレト" (Bereto), while the female is "ベレス" (Beresu).