Lost Potential

A Black Butler/Kuroshitsuji pre-canon story

By Kimberly T.

Several hundred years ago, long before a demon began to refer to himself as Sebastian:

The human he was currently serving, gave him no name at all.

That was hardly surprising; this contractor rarely used even the names of his fellow mortals, calling them by their ranks or servant titles when he bothered to do more than point and bark orders at them. Not that the lack of a mortal-bestowed name bothered the demon at all; he regarded such conventions as unnecessary at best, troublesome at worst. And when his current master called for 'demon', there was certainly no confusion as to who was being referred to.

This master was no better and no worse than most mortals that the demon had served in exchange for their souls; cruel, greedy, arrogant, and so on. This one's soul was strongly flavored with ambition, desiring to conquer the world; to systematically erase all the other empires and kingdoms currently in existence and crush their peoples under his heel. The terms of service for their contract were typical for such ambitious mortals: Kill whomever I tell you to kill, obey any and every other order I give you, and prevent anyone else from killing me, until I myself tell you that I'm satisfied with my conquests.

It was hardly the first time the demon had come across somebody wanting to conquer the world. But this particular mortal might actually be able to do it, or at least to conquer an entire continent during his lifetime; he was surprisingly canny for a man of such brutal tastes, and in addition to a demon servant he had hordes of loyal followers that willingly charged into war for him. He had made huge strides in conquest by either claiming or utterly destroying several cities, even before he'd forced the high wizard of a conquered city to summon a demon for him.

At first it had puzzled the demon, that this master still preferred to throw hordes of his loyal followers into each conquest, sometimes losing hundreds of them in a single battle, rather than simply bare the contract seal branded onto his shoulder and order his demon to do all the work. He didn't care about the loss of human life if he wasn't getting their souls to feed on, but his master's methods, while effective, occasionally struck him as inefficient.

But the demon eventually understood, after one particularly clever sub-chief managed to conquer a city and burn it to the ground without losing a single mounted warrior, came back to his king with his clansmen singing his praises… and was executed less than two weeks later on trumped-up charges of seducing one of the tyrant's many wives. Jealousy could be added to the tyrant's many character traits; he allowed no one to be either praised or feared more than him, not even his demon.

Not that the demon simply stood around idly all the time, not at all. He was often sent out at night, to secretly weaken the defenses of targeted cities and fortresses and make them easier to conquer. Undermine a wall here, murder a lookout there, disarm a fortress defense or two; nothing particularly difficult, but it was just enough work to keep him from getting bored.

The demon disliked being bored, because then he felt his hunger all the more keenly. Masters who didn't keep him sufficiently busy or entertained, didn't last very long; the demon would find ways to fulfill their contracts much sooner than they'd anticipated, on either technicalities or loopholes caused by careless wording of commands, so he could devour their souls that much sooner.

But so far, he wasn't bored by this master; he was even occasionally surprised by him. Such as today, when his master summoned him not to destroy anything, but to simply answer some questions about demonic origins and capabilities. He was used to human scholars and magicians asking such questions, but not those with the ambition to rule. Still, he answered readily enough, even when the questions turned to reproduction and inter-species breeding.


"Demon, I order you to use this slave for your seed."

Once again, the demon was surprised. He looked at the trembling and weeping young woman lying bound in front of him, and then over to where his current contractor lay lounging on fancy embroidered cushions. "Master?"

"You told me four days ago that it was possible to make a demon halfbreed; now I'm ordering you to sire one for me. We'll start with just one, and see how long it takes to whelp and train your get to where it can be used in battle. My slavemaster has guaranteed me that this slave is virgin, and ripe for breeding right now. So get to it!"

The demon inclined his head. "Yes, Master." He stooped down to pick up the girl, who screamed at his touch even though he was being careful not to scratch her with his talons at the moment, and started to carry her away.

"Where are you going? I said to get to it; you'll use her here and now!"

"Ah. I did not realize you wanted to watch, Master," the demon said as he set the girl back down.

"Yes," as his master's yellowed teeth showed in a savage grin. "I want to see you conquer her the way I conquer whole cities!"

The demon paused. "If I treat her that way, Master, she will not survive to breed anything, except maggots."

His master snorted impatiently. "You know what I meant; be rough while still keeping her alive and capable of carrying your get. Now do it!" as he shifted and stretched out on his cushions, his eyes glittering with cruel glee.

So the demon did. The girl's screams as he raped her were pleasant to his ears… but still, something felt… not right about the situation. He left her bleeding in several places when he was done, still pondering what exactly about the affair was offending his demonic aesthetics.


Two days later, the demon reported, "I can sense it, Master; a cambion is growing inside her."

"Good. How long did you say it would take before the half-breed will be born?"

"Six months, Master." The demon hesitated for a moment, and then added too quietly for the slave cowering nearby to hear, "I will also remind you that a human mother does not survive the birthing process." A cambion was not born, in the strictest sense; the demonic hybrid would claw its way out of her womb when it had grown strong enough, and its first full meal would be on her nutrient-rich organs.

His master said with a dismissive wave, "No need to whisper; she doesn't speak our language. And there's no need to fuss over the health of the brood mare; I have plenty of slaves, and I can always get more. Once we've seen how well your get can be trained to follow orders, I'll line up a hundred slaves for you to breed on, and sire for me an army of offspring!"

The demon bowed his head to his master, to hide a frown. It was easy to see what plans his master had in mind for the army of demon-human hybrids; they could conquer whole cities and even whole countries for him in a matter of hours. But while one or two cambion would not cause too much trouble on a worldwide scale, an army of a hundred or more of them would be guaranteed to summon the adversarial interest of the angels, the grim reapers and the Power on High. This contractor's plan would bring down their collective wrath on not just the tyrant, but the demon himself.

Still, if this breeding was typical to those passed down in demonic lore, it would take five years after its bloody birth for this half-breed to grow to its full size and strength, and have wits enough to serve as a soldier for a human warlord. Since his master had already declared he would wait to see how the first one turned out, there was no need for the demon to bother with thwarting such short-sighted plans just yet. In the meantime, he'd never witnessed the birth and first years of a hybrid before; this should prove at least mildly interesting.


Six weeks later, the demon finished secretly undermining a targeted city's defenses, to leave them easy prey for the hordes camped across the river that would attack at dawn. One final lookout murdered, and the demon slipped back out past the walls and silently sped across the countryside by the light of the crescent moon.

The shortest path back to where his master waited cut through miles of a dense forest, one almost completely untouched by humans. The demon paused at the base of a hill and looked around, sensing the abundance of deer, wolves, boars and other large animals.

Demon-human hybrids were typically born as grotesques, with clawed hands and backwards feet or other distorted features; marked from birth as radically different from the human cattle that they were spawned from. And while it took them only five years to reach their full size and far-greater-than-human strength, it typically took a full century for them to reach full maturity and the rest of their demonic heritage; the ability to consume souls as well as flesh and blood, to change their shapes and heal from normally fatal wounds. In short, while they were young, half-breeds were difficult to hide from scrutiny, and relatively easy to kill by armed humans working in large groups.

This forest had plenty of meat available for the killing, and no humans except for the occasional traveler passing through, which would be easy prey. The demon thought to himself that this would be a fine place for a demon-human hybrid to live and grow. He would drop it off here after the contract with his current master was fulfilled, to give the offspring a far better chance to survive to full maturity. Not that he actually cared about its future wellbeing, of course; it just suited his aesthetics, to tidy up a contract's leftovers.

Perhaps he would even stop by every decade or so, to check on its progress. He had encountered very few cambion over all his long lifespan, and each never more than once… partly because he usually ended up killing them, after the fools dared to challenge him for his prey. But even the ones who'd had sense enough to avoid challenging him, and who he had therefore let live, had never crossed his path again. So he really didn't know much about half-breeds beyond the common demonic lore; it would be interesting to witness this one's progress over the next century or two.

And perhaps… perhaps after its seventh or eighth decade, he'd start bringing it the occasional human to eat. With some active coaching from a patient demon, perhaps it would learn how to eat souls sooner than typical, and access its full demonic abilities sooner as well. He found the thought oddly pleasing, as he resumed speeding across the countryside back to his current master's home.


Two weeks later, the demon's master summoned him for another task, bidding him this time to take a fully human form for the occasion. The demon complied, and walked out of his master's tent and through the whole encampment dressed as a typical soldier.

The barbarian horde was not composed exclusively of male warriors; their women and slaves traveled with them as well, to do all the tasks that the warriors considered beneath their dignity. And though they were men of war sworn to die in service to their lord, even they had moments of affection. The demon passed a warrior who was on his knees next to a woman, pressing a hand and his cheek to her swollen belly, and giving a gap-toothed grin at whatever he felt within.


When he completed his task, the demon kept his human guise on for a while longer after leaving his master's presence, to walk through the encampment until he reached the tent where the breeding slave was being kept. He used a touch of power while telling the guards there that he was there for an inspection, and they let him in without question.

The slave's bruises and cuts had all healed, and at two months along, her belly was just beginning to swell. She cringed and whimpered as he approached, and he told her mildly, "There's really no point to that." He would not use her roughly again at this stage; he knew enough about human pregnancies to be aware that such actions might endanger the fetus.

He put a hand on her belly, and waited… but while he sensed the life within, it did not move strongly enough to be felt outside the womb yet.


Three weeks later, after completing yet another task for his master, the demon donned the full human guise again and went to see the slave once more. He brought with him a haunch of mutton, fully cooked to make it easier for the human to eat; he was sure the hybrid fetus would benefit from more meat in the woman's diet.

She stared at him when he handed it to her, and tremulously whispered thanks in her native tongue, which he nodded away as unimportant. She ate as he watched her in silence, and once she'd eaten her fill, she let him approach and lay a hand on her belly without cringing away.

Ah, there; it was very, very faint, but he could feel the tiny flutter against the walls of her womb as his offspring moved within.

On a whim, he sent a psychic pulse in its direction; one demon's greeting to another, usually done only when encroaching on another's claimed territory without the desire to conquer it. The offspring's response was even fainter than the flutter of its movement, but he could still sense—

But he was rudely interrupted by the woman screaming practically in his ear, and cringing away from him again. He'd let his eyes revert to their natural glowing state as he'd sent the greeting; apparently the woman hadn't realized until that moment that he was more than just a human guard. Normally he enjoyed screams of horror, but not when they were interrupting him like this—not to mention, drawing the attention of the actual guards outside. He huffed in irritation, and vanished from view just as the tent flaps opened.

At midnight, when most of the encampment was asleep, he hovered silently over the slave tent and sent down another psychic pulse of greeting, and received another response. It was pleasing to note that this time the response was ever-so-slightly stronger.

Of course his offspring would be developing well; that was only befitting the spawn of a demon of his power. And with guidance from its sire over the decades, why, it might be ready to consume souls and learn shape-shifting before aging even fifty years…


Six days later, the demon was hundreds of miles away from his master's encampment, destroying an outpost that belonged to the next country the warlord planned to invade. He was nearly finished when something fluttered at the edge of his awareness; he felt—a wrongness, a cry of—distress? Of pain, from—


He flung aside the human head he'd just ripped off and ran out, stretching out a taloned hand to slice through the dimensional walls as he went; ripping open a portal between Here and There, heedless of the amount of power it took him to do so.

He was back at the encampment in seconds, to find an alarm had been raised and guards were running into the slave's prison tent. He tossed aside the three that were in his way, and found—

The slave woman dying, with her hands curled around the hilt of a guard's sword that had been thrust deep into her own belly.

He yanked out the blade and threw it aside, and then ripped her belly open with his talons, seeking the life within. If he could keep it from dying with her, if he could use his own blood to nourish and—

No. Too late. Even as he drew the fetus out and cradled it in his palms, he could sense its life ending, slipping out of his reach to grasp.


It would have had a tail.

She would have had a tail, and at least the stubs of wings on her back.


"I've had that entire crew of guards beheaded for their carelessness," his master said with a scowl later that night. "The next brood mare will be better watched. Or maybe we'll just break her hands first, so she wouldn't be able to hold a weapon; I can spare another slave to feed her and wipe her ass. I'll speak with the slavemaster in the morning, about finding another suitable virgin for you to breed on."

The demon said nothing.


The tyrant's plans to resume the demonic breeding program were temporarily set aside, to focus on more personal and political matters; specifically, taking another wife, a tribute from some city that hoped to buy protection from his hordes with the lives of their own royalty. The demon only heard her name once, during the wedding ceremony he'd observed from afar; it was entirely possible that was the first time her new husband had heard it too. The tyrant certainly didn't use her name to address her, during the grand feast that followed the short wedding ceremony; a feast that the demon attended, taking human guise as a servant instead of a warrior. He maneuvered his way into being one of the servants who plied the warlord with food and drink, offering one delicacy after another and keeping his wine cup filled at all times.

After a few hours of feasting, the demon's master left the cheering crowds with a ribald wink as he entered the house where his new bride had been taken a short time ago by attendants, to be prepared for his pleasure. To her credit, the foreign princess didn't scream even once as her husband roughly claimed her virginity. Afterwards the tyrant stepped out long enough to display the sheet stained with the blood of her maidenhood, grinning as the thousands of feast attendants gave a rousing cheer at the sight. The demon servant, still in human guise and bearing a wineskin and a filled cup, sidled up to him just before he went back in with an obsequious, "Congratulations, sire; may her womb bear you another son. More wine, sire?"

The tyrant took the cup of wine and drained it, and then carelessly tossed it back at his attendant as he turned to go back into the bridal house. But the disguised demon pressed ever-so-gently, "More, sir? Or perhaps you would like some more smoked fish? Or are you entirely satisfied?"

"I'm satisfied," the demon's master said with a dismissive wave as he went back into the bridal house, doubtless looking forward to more sex with his new bride before she was sent off to be housed with his many other wives.

The demon grinned as the contract seal on his hand flared, before he walked away with the wineskin and cup, back to the feast... but as he walked past a tent and through the shadow that had been cast by the setting sun, he dropped both the cup and his human guise, and wrapped invisibility around himself before slipping into the bridal house.

The warlord had his bride on her hands and knees again, the skirts of her dress thrown up over her back; the demon cast a quick spell of somnolence as soon as he saw her, and she fell headlong into instant sleep even as the tyrant turned in outrage to see who had dared to interrupt.

The demon grinned again, showing his fangs. "Hello, Attila."

The demon's former master drew back slightly at his appearance, but was brave enough-or egotistical enough-to demand, "What the-why are you here when I didn't summon you? And how dare you call me by name, instead of 'Master'!"

The demon smiled even wider as he held up the wineskin. "I called you that while our contract was in effect… but that has now ended. Because you made a conquest of your bride tonight, and only moments ago, you yourself told me you were satisfied."

Attila the Hun blanched as he stammered, "I-I didn't mean it in that sense! Guards!"

The demon chuckled; he had ensorcelled the building before setting his trap. "No one else can hear you, Attila… but feel free to continue screaming."

Attila protested, "B-but why claim my soul now?! Haven't you enjoyed causing so much death and chaos while serving me? If you let me live, in a few more years we'll have conquered so much more! We can reign over the entire world together, and you'll have enough blood and souls to satisfy a hundred demons!"

"You want to know why, Attila? You would never understand…" Indeed, for once in his extremely long life, the demon barely understood his own reasons. But he still said out loud, "Because She would have been beautiful."

And then he pounced, and devoured.


Late the next day, after Attila's attendants finally dared to break into the bridal house and discovered their master lying dead next to his petrified and weeping bride, the entire Hun encampment rang with grieving howls and wails. Many of the Hun warriors even slashed at their cheeks with their knives, to show their grief with manly blood instead of womanly tears.

Attila had been found with blood crusted around his mouth and nose but no visible wounds on him; it had pleased the demon to offer the barbarian horde no signs of an attacker, no opportunity to blame this on an enemy they could crush in retaliation. The body lay in state as Attila's ministers argued amongst themselves as to how and where they would bury their fallen king, but the demon cared nothing for what they would decide.

His hand rested briefly on his torso, remembering what he had done ten days ago. He had taken the remains of his offspring far away from the encampment, searching for an appropriate spot… And then he had eaten the tiny corpse, every scrap of flesh and drop of blood she had possessed, because no patch of earth seemed worthy enough to be her resting place.

He had thought it might be some comfort, to have her always with him physically, but it was not enough, not—


He was a demon.

A demon, not some weak and maudlin human, prone to weeping and wailing over dead children and lost loves. Demons did not even have the capacity for such emotions.

No demon would ever, ever weep.

The whole affair had been an aberration from the start. He would do his best to forget it had ever happened. And in the future, he would take care that it would never happen again.

Keeping that thought firmly in mind, the demon turned and vanished from the mortal plane.