that's cool and all but in my personal opinion the EXO could be survivors of whatever hit earth, But they sustained injuries too severe to live from so made the choice to become EXO (robot\super human body with a human brain and maybe face) or they could have been full human once but volunteered to be enhanced into a super human war machine but the reason all humans didn't volunteer was because the survival rate too low (trouble bonding\linking with the machinelike) 10 in every 100 kind of low. but that's just what I think would be pretty f***ing AWESOME LOL