Conundrum

I am the angel to my demons maybe because my keys keep swapping in the lock, so I place heaven in the devil, and hell in God. I am the doom of my salvation, maybe because I make promises and keep slipping. So I make an enemy of the world, and a friend of my end. I am the antagonist of my hero, the hero and the demon lord. Made friends with death, enemies with life, so life pushes me out, and death pulls me back.