Byleth Eisner is a quiet, composed mercenary-turned-professor whose calm exterior hides a mysterious origin tied to the goddess Sothis. Born without a heartbeat and saved only through a divine Crest Stone, she grew up emotionless and deadly on the battlefield, earning the title “Ashen Demon.” At Garreg Mach Monastery, her silent strength, sharp instincts, and steady leadership gradually reveal a more human side as she bonds with her students. With the Sword of the Creator in hand and Sothis’ power within her, Byleth stands as a serene yet formidable figure—someone defined not by words, but by unwavering resolve and the connections she chooses to protect.