Well it appears that Pearce's roll has been shrouded with secrecy because of 1 of 3 reasons. Either that he is in the movie for a short period of time because he plays an unimportant roll. He is part of the flashback father / son scene. Or he is in a very important roll and that is why not much can be divulged. It has been speculated hundreds of times that the large Face could in fact be Pearce's? Perhaps he is actually the god who made humans in his image. It will be very interesting to see how this plays out.