Piper is running around risking her life & Pheobe's to carelessly kill demons, while Cole feels that he has to follow them around to protect Pheobe from being killed or losing another sister.
Piper is being dismissive of Paige while Pheobe is trying her best to welcome her as a sister.
Paige pays the sisters a visit & Pheobe shows her the book of shadows and tells her that it musn't leave the house but Paige of course doesn't listen & throws it out of the window then takes it to work where she starts using the spells for personal gain & of course there are very funy consequenses Paige has to pay.
Pheobe realises that she is no longer the younger sister now that Paige is in the picture.
After almost turning into a Furie, Piper (with some hellp from Paige) finally let go of all her anger towards Prue, and came to terms with the fact that she's never comming back. It was a nice touch to have Paige be the one to realise who Piper is really angry at & to help her through it.
The final scene when Piper finally calls Paige her sister was very touching.