It have many names. A/pep. Abbadon. Satan. Fenrir. Dragon, Wyrm, Snake. Many names, same entity. Immortal, strong enough to crush world in claws. One day it learn how to take seeds of itself, make lesser monsters. Demons you call them. Some immortal like it and some not. But all very powerful.
I was one. Chalix. Humans call me hell hound. I like them, they little but fierce. Candle flickers, lifes so short, but full of living. Demons are forever but do not so much living. Boring to serve Dragon always.
Demons cut through humans like leaves, many ages, until few left. Other creatures like Dragon, ones humans call gods, give some magic. They last longer. But magic not enough. Technology not enough. Endless war come to close in far future. Humans so few yet still fight. They love life so they give it for others. Demons do not do this thing.
But we can. So Chalix chose. Humans. They are so fragile, but not Chalix. Demon make good sacrifice. Piece of Dragon? Very powerful. It not understand this. It crush Chalix like bug but can not undo giving. So humans have chance now. You have chance now. Last stand. Do not waste, yes?
Chalix good boy.