Like his current form, Jack was mischievous, liked to have fun and play tricks on his friends and his younger sister. When Jack and his sister got themselves in trouble while they were ice skating on top of a frozen pond that was cracking, Jack made up a game of Hopscotch, and using his staff, Jack saved his sister from the cracking ice, at the cost of his own life. The Man in the Moon, seeing Jack's selfless act of heroism and sacrifice, shines his light and transforms Jack into a Winter Spirit, of which Jack rises up from the frozen pond and he is reborn as Jack Frost. When Jack Frost was reborn he lost all memory of his previous life and immediately began his adventures of fun and mischief.