Lillie had stage IV ovarian cancer. Addison did a house call to examine her. Lillie deduced that it had spread to her liver. She refused to return to the hospital, saying she knew she was going to die and the only thing she was concerned about was Milo, her cat. She couldn't leave him in the house alone. Addison agreed to take the cat so Lillie would go to the hospital.
Addison came to see Lillie in the hospital and met her new oncologist, Brian Reynolds. They told Addison that Lillie had decided to stop treatment. She believed she was holding onto her life too hard, but Addison agreeing to take Milo made the decision easier.
After she started hospice, Addison brought Milo in to visit Lillie, but when she arrived, she found Lillie already dead and her body being taken away.
Her closest family was her second cousin, Iris Rogerson, whom she asked to make her arrangements for her.
She was a fashion designer.