u just have to decline his offer when you get his route!
THANKS POOKIE, i figured it out after watching a gameplay vid but thanks :3
also while i was looking through the game files, i saw 2 pictures, one where unum's face was black (its looks like the cover but theres a duplicate in the files labled "badendunum") and there was also one for Septem where his face was also pitch black, are they like unreleased endings cuz i dont see them anywhere throughout the game and i clicked every option in the game but never saw those 2 photos in the game :C