Darcy Halford is Tom Halford's wife.
When Darcy's husband Tom was checked into Sacred Heart needing a new kidney, Darcy was ready to donate hers. However, when it was revealed by Dr. Cox that her's was not compatible for Tom but would be compatible for another couple waiting who would be able to give Tom a kidney is return, Darcy turned down the offer. Eventually, Turk convinced the Halfords to swap kidneys with the other family simultaneously, so trust would not be a factor. ("My Happy Place")