William May is the father of Melinda May.
Eventually, William and May got separated. In his old days, Lian would occasionally call William to check on him.
Father Daughter Reunion
Needing a break from S.H.I.E.L.D., Melinda May took some vacation and went to visit her father William in Sun City, Arizona, claiming she was there to help him while he was on rehab after a hip surgery due to a hit and run. However, William knew that her daughter had something else bothering her in mind and he suspected that she was hiding from something.
Later, William and Melinda were visited by Lance Hunter, who wanted to enlist Melinda's help to infiltrate HYDRA. After Hunter's departure, William confronted his daughter about her behavior, who expressed her wish to have a normal life. However, William told Melinda that she was not made for that kind of life and that she should face the shadows pursuing her instead of hiding from them.