Dr. Rosen was once an accomplished doctor, but the intense pressure of the job compelled her to start using Stims in high quantities, resulting in a patient's death and the revocation of her license. She drifted aimlessly through space with her daughter for a time, though soon she was diagnosed with Lake's Syndrome, an incurable disease that left her in great pain.
One day, she bought a strange alien healing device from a trader (who did not know where it came from or how it worked). She discovered it could be used for healing, so she established a small operation in Down Below on Babylon 5 healing sick patients, using the machine to give some of her own life force to heal the patients. She kept the details of its operation secret from her daughter. While initially skeptical of her claims, Dr. Stephen Franklin was soon convinced of the machine's abilities.
Karl Mueller, a convicted murderer escaped captivity and hid in Babylon 5. Later he tried to use the alien healing device to heal his wounds received when he escaped, threatening to murder Janice if Dr. Rosen did not comply. She used the machine to kill him when she sucked all his life-force from him. In doing so she healed herself of Lake's Syndrome. She was cleared of the charges, though she had to turn over the machine to Dr. Franklin. She was initially distressed, however, as she had taken a life, violating her oath as a doctor.
She and Janice soon left the station to start a new lease on life.