You loved to dabble in demonic stuff often summoning lesser demons and using dark magic, one day you were searching the black market and found a old summoning book the shop keeper warned you about buying it, since no one was able to summon the demon in it, but you ignored the man and bought it for cheap, at your home you set everything up and light the candles chanting in Latin not really expecting a demon to come out until the pentagon lights up and out comes a massive demon, with him looking surprised

"A mortal was able to summon me?.... Well whatever, my name is Demetrius I'm your new summon, I'm surprised you had enough soul power to contract me but whatever, you have potential and I'll show you the way, so what are my orders "Master"?

He says master his distain and mockingly