So, i kinda have this 'theory' with Phi, Ghirahim, and "the proposed others" so yeah, here it is:
For all we know, Phi could have been a part of Ghirahim's clan of "the proposed others" the whole time you were adventuring, and SHE'S the final boss. How else do you think Ghirahim always finds Link, seeing as how you'll be "meeting him" lots of times throughout your quest... maybe Phi is feeding him info. She seemed to have cold attitude in the gameplay demo. Maybe that's why she was sealed away and the Master Sword/Skyward Sword is so powerful, her evil heart is a driving force that makes her so strong.
so, what do you guys think?