(MAJOR SPOILER)

After doing some research, I figured that no, Arbert and the poster boy for this game are not the same people. HOWEVER... Let me ask you this. Did you mistook Arbert to be the one from the Answers cinematic scene? And when they revealed Arbert at the cutscene where they introduced the Warrior of Darkness, weren't you shocked and thought "Holy crap! This entire time, the poster boy is actually a villain? BRILLIANT!"