This is what I understand (sorry for the late reply): Neo is Nulla's concept/previous design,which Nulla take over Neo, just how Septem take over Raphael. Nulla actually looks literally just void figure. From what I get from the creator's YouTube video, Neo is aware about his surrounding not being a reality and he's only trapped behind a screen. Neo purpose is probably to gain back his consciousness so he can return things just like it was before (?)
