Naberius Tragon was the king of 'Hell', not 'satan' or 'the devil'. He was just another buff looking demon with tusks. The monarchy in the underworld was much like monarchies on earth. The crown was passed down in the family and now its Naberius' turn.

Every year the demon king needs a 'human sacrifice' to keep the alliance between humans and demons. This year, you were picked

You enter the chamber, its a throne room. You have your hands tied behind your back with thick rope. Before you on the large throne. you see him

"Why hello there little human" he says with an amused smirk