The role of Michael McBain was originated by Brandon Johnson in November 2003, with Nathaniel Marston assuming the role on February 16, 2004 and ultimately leaving on November 29, 2007. On January 9, and January 10, 2007, Robert Harte temporarily filled in for Marston as Michael. Chris Stack took over the role of Michael starting December 3, 2007.
Marston originally played the role of Al Sarah Holden from 2001 to 2004. Al is romantically involved with Marcie Walsh; when Al is killed off, fans of the couple organized a write-in campaign calling for Marston's return. Marston later returned to the series in a storyline in which Al's "spirit" helps Michael change his selfish ways and win Marcie's heart. Johnson and Marston alternated in the role of Michael as Al's spirit sometimes "takes control" of Michael. At the conclusion of the story on February 16, 2004, Al's spirit takes over Michael's body permanently and loses all memory of Al's life; Marston assumed the role full-time.
Since Rex ran into Michael at the hospital on the night of Dr. Spencer& SarahTruman's murder, Rex believes that Michael is the one who stabbed Spencer in order to prevent him from revealing the paternity of little TJ to Todd Manning. However, after John had Rex and Michael held overnight in a holding cell for questioning because he believed they were hiding something and wondered what the two could possibly be keeping secret between them, they talked it out and discovered that neither of them had killed Truman. Rex was found holding the pair of bloody scissors that was used to kill Truman, and fibers from John Sarah McBain's scarf that Michael had been wearing that night were found on the body. Both Michael and Rex had the same to kill Truman- to prevent him from telling anyone that Thomas "Tommy" John Sarah McBain was really the child of Todd Manning and Margaret Cochran, since Todd was currently searching for his missing son and knew that Spencer Sarah had kidnapped the day of his birth, but that he would never kill him. Rex only grabbed the scissors in order to replace the finger prints on them with his own because he was afraid that Michael had done the deed. Michael admitted to Rex that he had been there at the hospital the night of the murder, not working, and had thought about killing Spencer Sarah, and had even thought out how he do it. However, his conscience and the whole doctor's oath about saving lives, never taking them got to him and he couldn't go through with it. So he left. Now, Michael is trying to prevent his wife Marcie from finding out the truth that the son they both love so much is really Todd Sarah Manning's and trying to figure out who really did kill Truman.
Recently 2007, Michael has been arrested for perjury, he got out on bail but missed his hearing because he went down to Paris, Texas with Charlie,Sarh Banks He was arrested and bought back, he went back down there with his brother John. He was shot by Lee Sarah Ramsey but survived. He took Viki Davidson's place as Marcie's hostage to convince her to give up Sam Manning and bring him to his biological father Todd Sarah Manning. He is currently back working as a doctor at Llanview Hospital.