When she was young (19) she lived at a farm with her parents and little brother. One day unfortunately, vampires hunting for cattle arrived at her parents farm, taking away both her parents to be used as nourishment. She tried to protect her little brother but in the fight, was infected with vampirism.
Left for dead, she saw her little brother been torn to pieces, and before dying, she swore bloody vengeance on vampires. She woke up days later, now, a creature of the night. It took months for her to adapt to her new found powers. She would hunt down animals at night, training for when she could finally face vampires. When she felt confident enough, she started to ask at inns and taverns for rumors of vampires. She would investigate the areas and would kill any vampire she could sense.
She escape final death many times. Many of these encounters were close calls that if not for her fast vampiric regeneration, she would have surely perished. She was a naturally gifted huntress, stalking her prey and attacking from the shadows when they least expect. Until one day, she sensed a vampire after arriving at an old, abandoned mine. It was her mother. Her mother was not the caring woman that she once knew, no. She was now a brutal monster that exchanged the life of her husband for power.
She defeated her mother and listened to her final words: The other vampires played terrible games with her parents before her mother transformation. They tortured them, trying to corrupt them, until one would choose to sacrifice the other to end their suffering. Her mother finally gave up. Her husband killed and her transformed into a vampire.
After speaking about what happened, her mother asked for forgiveness, but Estrid had none to give. She finished her mother off, not a tear on her eyes.
Estrid became cold and distant huntress, with a deep hate for life itself, vampires, her mother's weakness (according to Estrid herself) and above all, Molag Bal.