Mary Henderson was the owner of a house inhabited by a Soul Eater in 2008.
On her family's first night at the house, everyone was in bed. Then her son called out for help, saying he heard strange noises sounding like footsteps.
Mary and her husband ran to his room, but by the time they got there, their son was on the ground, unconscious. Mary noticed her son's room was cold and that the lights were out. Mary also noticed a strange mark on her son's ankle, resembling a handprint.
Following the interview with Rufus and Bobby, Mary had returned from the hospital to get a favorite teddy bear of Will's, only to be taken by the Soul Eater.
While Bobby's Celtic Trap sigil initially imprisoned Mary, Will and Bobby within the Soul Eater's nest. The Men of Letter's Killing Sigil was able to kill the Soul Eater many years later. Given that the Nest existed outside time and space, the Soul Eater's death and the destruction of its Nest in 2016, freed all souls back to their respective time.
In 2016, Mary is approached by Sam and Dean who wish to know about the incident. She tells them about her experience in the nest, what she saw and what it was like. At this point, Mary's old home belongs to Naoki Himura.