Marcus Kane

Marcus Kane is the brother-in-law and secret lover of Kathleen Kane, a patient at Grey Sloan Memorial Hospital.

Kathleen's Accident
Marcus came to the hospital after Kathleen was injured by a shattered baseball bat. Before Kathleen went into surgery, she instructed Leah to tell her husband if she died that she had slept with his brother.

Kathleen Kane
Marcus had an affair with his sister-in-law, Kathleen.

Dante Kane
Marcus and his brother, Dante, appear to be close.