The December 1977 full moon falls on Christmas Day, forcing the Marauders to stay at Hogwarts while Lily goes home. The cheerless holiday is overshadowed by tension and Remus's guilt about keeping his friends from their families. After the transformation, Sirius reveals he plans to tell James about their relationship over the holidays. At the Potters', Remus learns about his mother Hope from Mrs. Potter, who knew her when they were both pregnant, and receives her current address from Mr. Potter.