Keith Kalber

Keith Kalber was a patient at Grey Sloan Memorial Hospital who received the first HIV+ to HIV+ kidney transplant in the state since the new law went into effect.

HIV
Keith was diagnosed with HIV and spent years getting that in check.

Kidney Transplant
At some point, Keith went into kidney failure. As he was HIV+, nothing could be done to treat him except dialysis until a new law went into effect allowing him to receive a kidney from an HIV+ donor. Marty was a good math, so they set up for Marty to donate his kidney. However, upon hearing the potential risks to the donor, Marty briefly backed out, unbeknownst to Keith. One he saw Keith's reaction and how good a friend he was, Marty decided that he was willing to go through with it despite the risks to himself. The kidney was successfully donated.

Marty
When Keith needed a kidney, Marty offered upon finding out that he was a good match.

Other Friends
Keith mentioned that many of their other friends had died and they survived.

Notes and Trivia

 * He was with Marty when Marty received his HIV diagnosis.