Within the series' narrative, Cole is a Cambion, half-human and half-demon by birth and blood, and better known to the demonic world for over a hundred years as the legendary demonic assassin Belthazor. Cole is dispatched by the Source of all Evil to kill the Charmed Ones only to fall in love with then-youngest sister Phoebe Halliwell, renounce evil and become a close ally of the Charmed Ones. Though Cole eventually completely rids himself of his demonic nature, and marries Phoebe in the fourth season, he never gains the trust of new youngest sister Paige (Rose McGowan).