Brey is the daughter of Valtar ir'Mallon, a famous Thrane general. Later in life she joined the Thrane army and became the captain of the Inmistil Rangers. She was assigned a second in command named Egen and had a white warhorse named Thalin. On Vult 11 993 YK she participated in a battle near the Cyre River where she fought against a Karrnathi army. She was defeated and she and her unit were captured. She was then turned into a vampire by Wultram a captain of the Karrnathi army. Due to the nature of vampires she was forced to obey Wultram by wearing the badge and uniform of the Karrnathi unit Wultram commanded and ordered to commit unspeakable acts. She fought against her vampire nature and cried tears of blood every time she fed. She and her rangers were stationed in a former Cyran fortress now turned into a Karrnathi research facility. The one who ran the facility was a necromancer named Marbulin Dravuliel. During a ritual that opened a portal to Mabar Dravuliel was ensnared by a tentacled creature. Wultram attempted to aid Dravuliel and though successful was killed by the Mabar creature. Free from her vampire creator Brey fled the fortress.
After escaping she travelled, developing her vampire powers and swearing to destroy the Karrnathi undead. On the Day of Mourning she was in Karrnath not far from Fort Zombie. She had used her powers to enslave a supply clerk at the fort and used him to inform her where the undead troops came from.