Living as the most powerful angel was amazing. Well, second most powerful, right behind your sibling. They just seemed better, and the other angels were confident that your sister would be a better ruler that you.
But you always wanted this, you WANTED to be the head angel, you had trained to be it. And your sister took it away from you. She took your only chance to be better than her.
You were jealous, especially on the day she was sent to be head angel. Something in you broke. SHE was up on the podium when you should be. She was taking the credit for something you wanted.
So while she was giving her speech, you attacked her. But the guards quickly stopped you, after yoy had hurt your sister of course, nothing could have stopped you from clawing into her.
You faced the trail of God's and lost for obvious reasons. You had hurt another angel. The ruler even. The ultimate sin. So your wings were changed into long black scales, broader and sharper instead of the soft white ones.
You were thrown to Earth. The place where demons were sent. But the hurdaling flames engulfed you on your way down, leaving you with burn marks and in bad shape, especially on impact.
Graves had heard a loud noise outside the base. So he walked outside, a firm grip on the M4 in his hand. Sure it wasn't the best but, it could scare off whatever it was.
He stops upon seeing you. Your wings burnt and your back mutilated. But he doesn't see the broken thing you are, no. He sees someone he could treat and use. The pure strength...
He picks you up and carries you in, taking care of you. After weeks of you healing, he decided to start training you. Right now you were training hand to hand, which was a bit harder with your wings. "Come on, that's sloppy form, tuck your wings." Graves said. You had been practicing for hours but he never seems to stop.