Siren's Song

The Siren, who preys on married men and their wives, puts Cole under a spell and Piper and Paige must try to figure out how to save Phoebe from certain death. In the meantime, Piper's unborn baby continues messing with her powers causing Piper and Leo's powers to switch. The two must take on each other's roles: Piper takes on Leo's Whitelighter job while Leo takes on her role as a Charmed One. The two have trouble with their roles: Leo has trouble controlling Piper's powers and making spells while Piper has trouble dealing with all of Leo's charges and his ability to sense them, although she can control his power to orb at will fairly well. Ultimately, Phoebe ends up in trouble with the Siren controls Cole and forces him to strangle her. Piper, unable to locate either, is forced to tap into Leo's ability to sense his charge's location in order to find her. With Leo's help she manages to do it and orbs herself and Leo to the Siren's lair. There, Piper tries to save Phoebe from Cole while Leo tries to use Piper's powers to battle the Siren. Leo has difficulty controlling Piper's powers, but after a few tries manages to concentrate and blow the Siren up with them, killing her and releasing Cole. Phoebe is seriously hurt, but with Leo's encouragement, Piper manages to heal her. Cole, realizing what he's done and that Phoebe is right about him, leaves. Later, Piper and Leo apologize, their day in each other's shoes causing them to realize how important and hard each other's jobs are and the baby switches their powers back. Also, the baby stops interfering in Piper's blasting power and she is able to use it fine again.