Mary was involved in a romantic relationship with John Grayson, which was hindered by the family feud between the Lloyds and Graysons. When Lila Valeska was murdered, and Alphonse Grayson and Owen Lloyd were arrested due to a fight between the two, Mary and John were examined by Dr. Leslie Thompkins, while John told Thompkins that the fight was caused by Mary's idiot uncle Owen doing his thing, Mary told him that he knew that Lila had to be the cause of the fight. At the Gotham City Police Department headquarters, the two later argued over who had murdered Lila Valeska, though Mary along with John later returned to thank Gordon for figuring out who had actually killed Lila, leading their two families to reconcile, and John and Mary getting together.
- According to Sean Pertwee (Alfred Pennyworth), Mary was pregnant during the events of the episode.
- Mary Lloyd was created by Bob Kane and Bill Finger, first appearing in Detective Comics #38 as the mother of Richard "Dick" Grayson, the first person to take up the mantle of Robin.