Kevin Mason is the brother of Ryan Mason.
Kevin's brother, Ryan, who was already in kidney failure, developed cardiomyopathy secondary to the dialysis. His kidneys had completely shut down and he was added to the transplant list. He knew that his chances were small of getting a kidney because of a prior blood transfusion which made him a difficult match. Charlotte suggested that he contact his brother, who would make a better match as a family member. Ryan instead tried to buy his way to the top of the transplant list, but Charlotte said it wouldn't work. He agreed to call his brother.
His brother, Kevin, came to the hospital, but then Charlotte found out he was intellectually disabled. Ryan admitted that he didn't want to call Kevin because he's needy. He needs to have everything explained multiple times. He said that his brother would do anything for him.
Kevin was a good match and said he wanted to donate the kidney. Despite Charlotte's reservations, the surgery went forward.
The surgery went well and Ryan pledged to be different to Kevin. However, while they were playing Checkers together, Ryan started bleeding into his abdomen and had to be rushed back into surgery. His body had rejected the kidney, so he was going to die.
They explained the situation to Kevin, who didn't understand that his brother wasn't going to get better. Ryan then tried to get Kevin to understand that it wasn't his fault, but Ryan wasn't going to be going home.
After his parents died, his brother took over paying for his care, but stayed mostly uninvolved in his life.