Howling:Prisoner Zero knows something The Allience does not

This is my first post on the tardis wiki so bear with me despite me having no credability yet. I have just watched The Pandorica Opens and have had an idea, throughout the series many people have said the other 'the pandorica will open' but to my knowledge only Prisoner Zero (and creepy Tardis voice). Could it be that Prisoner Zero knows who this 'voice' is or what it's up to, or it could be finale Doctor going back and telling Zero about it after the problem is solved, as to what the creepy voice is I have no idea could be Omega, Valeyard, Black Guardian or something new all together. Thanks for reading and please share your thoughts (not sure how to sign posts yet so this will have to do) LeighPouse.