|Family||Valgren Treesong (Brother)|
A secretive Elven man living deep in the forests of Violl's Garden. He bears the lonely task of holding onto Celia's Song of Life and spends his days quietly travelling through the forest and saving lives where he can.
Having accepted his duty from a young age, Cosmas left his family early on to protect them from the dangers of the Song, particularly hoping that his actions would keep his younger brother Valgren from harm. He is aware that teaching the Song to another means forfeiting his own life, which partially fueled his decision to separate from his family early on.