As a human, she served as a lieutenant commander on the USS Nelson in the 2370s.

In 2399, at the age of 65, Morrison was presumed dead when her shuttlecraft fell apart while in transit to a Federation planet. In reality, after the shuttle had started to come apart, an unknown sorquine had entered and "assimilated" Morrison, turning her into a sorquine as well so she could survive the vacuum of space. She was picked up three hours later by the USS Paramaribo.

After becoming a sorquine, Morrison had retained her personality and professional knowledge. However, she had lost all of her memories, so the crew of the Paramaribo helped her rediscover her identity. Because of her memory loss, she considered herself a distinct individual (although she kept the same name), and so she re-enlisted in Starfleet, gaining an immediate promotion to chief petty officer and a post as the Paramaribo's counselor (relieving Kelper of that duty.)

Her parents were still alive as of 2405.