Spoilers
At some point during Beatrix's time with Osric Gemdelver, he became sick with a disease that no one could seem to cure. Beatrix, therefore, set out to find something or someone who could help her husband. Though she found a cure on her quest, she returned too late and found that Osric had already passed.
Beatrix was devastated by Osric's death and became obsessed with pursuing means, through magic and meditation, that could perhaps bring him back. One day, she was screaming her frustration into the darkest pits of despair when a voice whispered back: "I can help you." Beatrix would later learn this voice belonged to Reidoth the Druid
She was given whispered directions in her dreams, which she followed unquestioningly in her grief. These directions eventually led her to one of Reidoth the Druid's old laboratories. There, on condition of her service toReidoth the Druid, she was given information about the rites of vampirism. This allowed her to bring Osric back as a vampire, but the rite also bound his existence to Reidoth the Druid, bringing the couple both into service to the "Whispered One".