Sonia is part of Griffith's reformed Band of the Hawk and is extremely devout in her admiration of him. Her parents were killed when Kushans came to her village. She was held prisoner by them until Griffith, with his apostles, rescued her and others in an assault against the invading Kushans forces.

Sonia, despite being surrounded in a surreal and sometimes horrific world, remains abnormally calm and shows no sign of fear for her life. On the contrary, she is amazed and cheerful about her position in the Hawks. She is gifted with the power of clairvoyance, which is amplified when she is near Griffith, with whom she has a childish infatuation and, because of this, is very jealous of Charlotte for being betrothed to Griffith.

Sonia uses her ability to sense people's emotions and see visions of the future to aid in the new Band of the Hawk's campaigns. She befriended Schierke when they met in Vritanis and foresees they'll meet again: referring to Schierke as an owl and herself a kite playing in a moonlight forest. She also struck a close relationship with the distant Irvine.

Sonia is a very clear cut counterpart of Casca: both have been rescued by Griffith, and both have had crushes on him.