Piper didn't want to let go of Prue, for fear that somehow this was all in her head and she wasn't really here, that if she let go, Prue would simply vanish. Because logically, she couldn't be here. Yet, here she was. It was a very confusing moment, but mostly she was just overjoyed at seeing her sister again. Piper decided that even if this was all in her head, she would revel in the time she had with Prue because it may all end before she knew it.
Finally, she slowly released her sister and stepped back a little. She still couldn't believe this was happening, but honestly? She was really, really glad to see Prue. In all of her suspicion and shock, Piper had almost forgotten that she was in a strange and unfamiliar place. "So...where are we, exactly?" She asked, assuming Prue had been here longer than she had and would probably have some answers. "I was up there talking to Leo," she explained, deciding to leave out the part about the arguing for now, "and then I was here. I don't know what's going on, but I really, really need to get home, Prue. There are...a lot of things going on right now and I really can't do this..." she searched for the right word for a moment, "demonic plane of existance or whatever this is right now."