For example, one parent told us that her son had a playmate named Nobby, a little invisible boy. The child also mentioned Nobby when he was asked about pretend friends, but when we asked how often he played with Nobby, he scowled and replied, "I don't play with him." We learned that Nobby was a 160-year-old businessman who visited the child between business trips to Portland and Seattle, whenever the child wanted to "talk things over." The boy's mother was as surprised as we were.
Imaginary Companions and the Children Who Create Them, Marjorie Taylor, OUP, 1999, Chapter 2, Page 21
Fantasy play of various types can play a powerful role in children's ability to overcome fear. This point was brought home to me by my daughter's reaction at age 3 to the gift of a small box described as containing a "baby ghost." Amber had developed a fear of ghosts that disrupted her sleep and made her anxious when left alone at bedtime. However, when asked if she would like to take care of the baby ghost, she was eager to do so. For more than a week she carried the box with its invisible contents with her wherever she went and was very much absorbed in this fantasy. The baby ghost and its box were eventually abandoned for other toys, but Amber was never again bothered by a fear of ghosts. Conceptualizing the ghost in the box as something weak, tiny, and in need of care seemed to remove the scariness from her thoughts about ghosts in general.
(Endnote:) The children at her day care took turns one day taking the box into the bathroom, turning out the light, and letting the ghost out of the box. In the pitch dark of the windowless bathroom, all the children were able to enjoy playing with the baby ghost.
Ibid., Chapter 4, Page 75
Sometimes the child involves family members in her game of pretense. A colleague of mine has a daughter who as a 3-year-old enjoyed fantasy games of impersonation that required the cooperation of the entire family. On her request, everyone shifted to alter identities on Wednesdays. The girl became a boy named Rainbow Cutter, the younger brother became a girl named Rainbow Cut, the mother became a little girl named Sweet Flower, and the father (who got the raw end of things, I think) became a piece of string named Hagar.
Ibid., Chapter 3, Page 50