Romeo and Juliet

Phoebe thought that Romeo and Juliet was just a story by William Shakespeare, until she met Romeo and Juliet.

Innocents Lost
When William Shakespeare wrote "Romeo and Juliet", he did so with a quill pen made out of a phoenix feather. This had the effect of making them repeat the cycle over and over again. They would meet, marry, live their lives, and die. By the time they met Phoebe, they had been married at least a dozen times over the course of over four hundred years.

They thought maybe being married by a Charmed One would end the cycle. Phoebe got back her power of empathy due to the intense feelings coming from them. Shortly after that, Coop arrived. He instantly recognized the iconic couple.