I've watched the anime, and read part of the manga, but let this idea grow in my brainhole for a little bit.
Mist blinked the uncomfortable light out of his eyes. He was in an alley, where 3 dungeon slimes were about to melt the flesh from his bones. He gulped, wishing he had listened to his father. Which would be unusual for a teenager, but demons age differently. He has lived 235 years and counting. He had an argument with his father which nearly leveled 3/4 of the West US coast. Which would have been rather unfortunate. Especially because he wanted to vacation there. California beaches, move on a bit inland to Vegas. But back to the matters at hand.
Mist's POV
I was unsure how to destroy these worthless trashsacks. Should I vaporize them, or open a spatial rift and send them hurtling an infinite number of demiplanes? But they don't have minds to be shattered by such a traumatizing experience. Or fight them, blade and fist to strangely cohesive acidic sludge. "Nah," I thought. "I've got places to be." I lit my right index finger ablaze and, carving his rune in the air, called "Bios!" There was a brief flash of purple light before a giant crack opened in the ground. A metal-boned skeleton crawled up, a green bubble of slime trapped in its ribcage. It had orbs of purple fire for eyes. It pulled out two of its ribs, which grew into two dark scimitars. It hacked the slimes to pieces. Then it kicked their remains across the floor and burned them to a crispy dust. It looked its soulless sockets at me. But I wasn't scared, though. Bios has been my friend for forever, and I have many fond memories with him. He pulled out one of his ribs, which became a blackened, curved scimitar. He chopped the first two into tiny cubes of slime, vaporizing the third. He then turned to me, and in his deep, booming voice saying "We should get moving, Mist," I turned, and my hateful glare actually made parts of him begin to smoke. "When we are on official business, you will address me as Mephistopheles or Master. Understood?" He smirked as much as a skeleton could, and said " Of course, Master. but I had no idea we were in 'official business anymore. I assumed that after your father banished us, we were done with doing that too." I looked at him in an annoyed fashion and said "We have person matters to deal with. But try to seem at least a fraction as dignified as you used to. For me?" He sighed in a very false way and muttered "Sure. Nothing more dignified than a demi-demon serving an entitled runt like you." "I sincerely hope, for your sake, that you are on better behavior. Princess Hime is a hard opponent." I looked up into the cold night in Sasanaki town. "And for our sakes, friend, I hope that we even have the luck to beat her as is."
Enjoy? Don't worry, I'll do more.