Claudia was a pre-Immortal who had known Duncan since she was 14. Duncan, noting her gift with music, financed her musical education at The Juilliard School in New York.
As an adult, Claudia became a noted classical pianist. In 1996, she was delighted to see Duncan come to visit her while she was practicing the piano in a concert hall in Seacouver. But an unknown Immortal sawed through cables above her on the stage, causing the lights to fall, crashing on to her piano. Claudia was saved from injury by MacLeod. Duncan was concerned when he sensed another Immortal close by. He took her to his loft for protection, but later allowed a visit to Joe Dawson's tavern where Methos sensed her latent immortality and asked Duncan if she knew what she was, Duncan replied that she hadn't a clue.
When the mystery immortal revealed himself to be Walter Graham, an old friend of Duncan's, he unveiled his plan to kill her at the peak of her talent, leaving MacLeod appalled. Walter eventually succeeded in killing Claudia with a bullet in the chest, and she was initially happy that she had become Immortal, much to Duncan's frustration because her death was not her free choice or even an accident. Inexplicably, the change had a negative effect on her talent. This did not sit well with Walter, who kept pushing her to try harder, to no avail.
Duncan decided to take her to a Buddhist monastery for safety so she might have time to adjust to her new reality. But Walter ambushed them, and shot Duncan dead. Claudia said she could not play anymore, that Walter stole her genius from her. Walter was furious with frustration, and put his sword to her neck. She was terrified, but when Duncan recovered, he in turn threatened Walter's neck.
She told Duncan to let Walter kill her. But Duncan told Walter to put down his sword, and ordered Claudia to get inside the monastery and wait for him. Walter turned and beat Duncan's sword aside, he told Claudia that he would "...be in in a moment; MacLeod knows which of us is the better swordsman." They fought, with Duncan eventually disarming Walter, and told him if he swore that he would leave Claudia alone, he would spare him. Walter said, "What value will my life have, without her genius to color it?" Duncan threatened Walter's head again, then Walter quickly told him that he would leave her be. The two men parted ways.
Duncan later told Claudia that he would start training her to use a sword, but she declined, saying that only if she is afraid of death can she pursue her dream. Duncan insisted that she learn how to use a sword because "While you're out there chasing your dreams, someone else will be chasing you." But Claudia said she had to live her life her way. Only the fear of mortality would let her perform up to her standard.
Duncan later met with Joe, who assured him that a Watcher would be assigned to her soon. And, that the Watcher, in turn, would keep an eye on her.
Claudia was mentioned again in the final season episode, Indiscretions, when she is said to be playing the Albert Hall in London.