Rosalie was born to a Hunter and a woman he met in a cafe. Her father was soon killed by Grimm during a mission, which led to her mother going into premature labor. She was a premature, but has shown that she has an incredible fighting spirit. Rosalie was soon found to be a knife-fighter after she invesigated in her father's office and messing around with his weapons collected from his body.
Rosalie continued to train in secret behind their house while her mother met another man and soon she had a stepfather with a younger sister on the way. Lillian was born not too long afterwards and Rosalie developed her overprotectiveness and mother henning behavior. She started at Haven at the age of 18, joining the Team CRNT, or pronounced 'Carnation'.
She luckily gets along with everyone in her team, and is entering her third year at Haven Academy and is looking forward to what the remaining two years bring.