Before he was a friendly ghost, Casper was a friendly—and breathing—living boy. Who saw dead people. In the kiddie romance Ten Things I Hate About Boo, Casper attempts to charm a beautiful-but-angry ghost girl who lives in his house so that she can find peace and stop haunting his family.
The too-trusting Casper learns the hard way that the line between his world and the undead is much less scary than people think when his jealous ghost girlfriend deliberately gets him lost in a snowstorm so he'll catch a fatal case of pneumonia. On his deathbed, the saintly sick child vows to spend the afterlife as an ambassador for apparition/human relations.