Third Episode Reveal [Spoilers]
So now we know what the deal is with Piper. More or less. Still a lot of open questions. Her body seems to be mostly organic. She has organs that can fail, she eats food and the chemical energy from that is probably what powers her synthetic components - which is why she never has to recharge from a wall outlet. So was that body grown for her specifically or did it belong to a child who suffered brain death?
Next episode looks like Jo is trying to answer the questions, is Piper alive or just an imitation of life, and can she be trusted? The way the girl doesn't seem to sleep much (if she does at all) and has that tendency to be there beside people without warning, that kind of stuff suddenly seems more ominous.
I'm guessing she turns out to be good though. Jo won't keep her around if there's any real doubt, and the interaction between Piper and the rest of the family is an important part of the show. So far they haven't shown a tendency to drag things out so that's probably going to be resolved by the end of next week. It'll be interesting to see where the series goes after that. They're going to need more long-term plot threads once it's no longer being driven by the central mystery of 'who is Piper?'.