Christy has now managed to convince Billie that the Charmed ones are too self obsessed to help the 'greater good' so when Paige, Pheobe and Piper attempt to invlolve the rest of the magical community.
When a demon attacks and kills one of the three nympths that protect a lake, the Charmed ones try to help. However, once the demon is destroyed, the nypmphs decided Paige should replace the fallen nymph, and they won't take no for an answer.
