One summer evening during a violent thunderstorm a mother was tucking her son into bed.
She was about to turn off the light when he asked with a tremour in his voice, "Mummy, will you sleep with me tonight?"
The mother smiled and gave him a reassuring hug. "I can't dear," she said. "I have to sleep in Daddy's room."
A long silence was broken at last by his shaky little voice: "The big sissy."