Charmed - Season 4 Episode 20 -

Phoebe is irritated with the lack of attention of Cole and destroys five of his demons in a couple of days. She has a premonition of a demon killing the innocent Greg Conroy, she tells her sisters at the Halliwell manor and together they go to an alley and save Greg Conroy. However, when Phoebe spares the demon, Piper tells that she must take a side and Phoebe decides to stay with Cole. When Cole is pressed in the underworld to kill Greg, Phoebe has to decide which side she should stay: in the evil side with Cole or in the good side with her sisters.