Millions watched as a single man, or something like one, slaughtered every single soldier of the Royal Army, hundreds of highly trained men, and then executed their king with a smile on his face.

On that same day, said man stood upon the dais where only those of royal blood had stood for almost twelve centuries, ironic as he was covered in royal blood, and announced to the entire kingdom that the world would end by his hand in 100 years. All sentient races simply wiped clean from the slate; all life annihilated without discretion. All this, unless, before the century had passed, someone ended his life.

Then and there he named himself the Demon King.

The last word he spoke that day was a simple one.

“Run,” he commanded the masses as the castle behind him exploded. The bright mushroom cloud illuminating the sky and reflecting off his vicious grin.

Ninety-Five years had passed since that day, as a commander of the Royal Army of the kingdom of Sanguis stood on a hill above the plains, inspecting his troops. Hundreds of men were in front of the dark fortress armed with the best weaponry the kingdom could afford.

The latest spellarms, the guns loaded with ammunition specifically designed to pierce the enemy's shields. Enchanted weapons crafted, by the greatest smiths and battle-mages the world had to offer. Those mages themselves were here as well. Golems formed of cursed-steel and fueled by destructive magic. The most elite knights the kingdom had ever trained, brought up specifically for this mission. Weapons of war, designed by the greatest dwarvish engineer ever known to live, and if all else failed, a magic item designed to destroy this place and everyone in it, reducing them all to ash with the push of a button.

That is what they had come here with.

And yet his men were all dead. All the weapons destroyed. Even their last resort had been shattered into pieces, the enchantment thoroughly disarmed. The battlefield was coated in gore, the remains of his men scattered like confetti across the courtyard. The only figure left standing… One figure, one man had done this… all of this… alone. It turned to him.

The commander trembled in terror. He had come here prepared to die, but seeing what this thing… this demon could do… it looking at him was more than his mind could handle. Its gaze felt like a promise to tear his very soul apart.

He could feel it as it took a step closer, each movement sending slight shudders through the ground. The glint of light as the sun caught its horns, like red-stained glass.

It was in front of him now, its face too human for the monster he knew lurked within. Its clothes and skin clean despite the slaughter, as if even the blood had known not to touch it without permission. The commander prepared to draw his sword in a futile last stand, but he was too late. The thing was already reaching out its hand to… take the commander’s in a firm handshake?

The commander looked down to see that the thing was indeed shaking his hand. How had it gotten his hand…?

“Hello,” It said. “Allow me to introduce myself. I’m the Demon King, but you know that already. What you don't know, and I'm sure you're wondering about, is why you're still alive. Quite frankly, my friend, I have a deal for you.”

The commander stared in shocked silence, trying to process what he had heard, then he barked a laugh that was more nervous fear than amusement.

“Why would you want to make a deal with me? And why would I ever take what you offered!?” he asked, drawing his sword and slicing at the Demon King’s neck.

The demon dodged smoothly, seeming to less move out of the way than teleport to the side as the sword passed.

“You? Well, because if you don’t, I’ll end the world, at least for humanity and the other sentient races. But again, you knew that already. Your real question was why I would want to make a deal with you. Honestly, I'm tired of this whole Demon King gig. It’s time for me to move on to something else, but sadly there are only two ways for this to end.”

The knight slashed again. This time the Demon King didn't dodge, instead letting the blade pass through him as if he wasn't even there.

“One, I destroy the world; two, someone kills me, and as of yet no one your kingdom, or any kingdom for that matter, has sent has even been a minor threat. I don't really want to destroy the world, though. That would be a waste of… well, everything. Even still, my altruism only goes so far, and I have given you all every chance I could.” He stated, snatching the sword from the commander this swing and snapping the enchanted blade in two with one hand,“Yet you continue to be oh so incompetent. And before you ask, no I can’t just let someone kill me. That would be shameful, and I’m not willing to go out like that.”

The demon grinned like a slimy salesman. “So here’s the deal,” he said, leaning in. “Let me make my own murderers.”

He stopped as if he had just dropped the revelation of the century. The commander just frowned.

“And how do you suppose you do that?”

“hmmm… well, we could do it in a classroom setting but I’m not a tentacle monster.”

“wha-“

"I know! I’ve been wanting to go adventuring. Do you still have that old ‘kill the Demon King’ quest lying around...?”