High Watcher Belial

"Who's Belial?
"Best if you not know. As for what i can tell you without inviting problems, just know that he is quite possibly the most powerful person in the Federation. Equal to Augustus himself"
Aiden, speaking to a young Meros on Belial

The Order, the agency charged with fighting the biggest threats to mankind is an elusive and enigmatic organisation indeed. Not much is known about its cryptic structures, except for the fact that there is one. Its chain of command is virtually unknown to all but a select few. These people battle the foes of mankind from the darkness, be they alien, demon, traitor or whatever else. They have been trained to give every waking hour of their lives to eradicating these apocalyptic threats, which results in most of the orders members to gradually lose their humanity over time
Amongst all of them, one individual stands as the most enigmatic. Only two people in the entire Imperium know about him, and that is the leader and the Supreme Commander of the Imperial armed forces. To others, he is known as Belial. A warrior who is powerful beyond imagination. He wields near equal power to the leader himself, and even his loyalty to him is sometimes doubted due to the enigmatic way he works in
Yet, Belial has sacrificed many things, the most valuable of which was his humanity. He fights to keep mankind alive, and fights in the same way as his enemies fight. Though the Orders tactics are often described as inhumane, it is a necessary evil which abhors even the watchers, and mostly Belial himself. He locks up whatever humanity he has remaining and wages war against demonkind and the enemies of man, like a hero of old who will never be remembered by the people for his efforts