1 fallen

Eren Jaeger. God's brightest angel and only son. 'Falls' from the safety of heaven and lands in a dirty disgusting alleyway. Broken wings and wounded soul he tries to ask his father for help. He finds his way to a shop where he is given a key.
Only to find out his fathers betrayal.

Levi Ackerman. The devil himself. Is told about gods plan of a war and hears word of gods 'key'. The 'key' is his ultimate weapon against Levi. then Levi discovers what the key really Is and uses all his strength to protect the 'key' at all costs. Knowing God will only destroy it.