Content Warning: Child abuse/cruelty to children, human sacrifice, psychological manipulation. This one is very dark.
Memorandum on the Mawic Diabolist Affair for the V.V. Bishop Hunwy
Three weeks from yesterday, ten children in the village of Mawic (Ardale Parish) did not return from their afternoon play in the pasture, and the shepherd was found with his throat cut. A traveling Journeyman Delver, Iffis of Bacot, was staying the night in the village and was present when the alarm was raised. He found tracks leading into the woods and gathered men to follow them. In the forest they found the children and their abductors, a man leading a pack of tamed wolves (sorcerously?). The wolves were successfully driven off and the man killed in the ensuing scuffle. Three of the children had been killed by poisoning. The remaining children reported that after being forced into the woods by the man and his wolves, they were made to drink a potion that knocked them out. Three of the surviving children described having what were most likely tief-dreams. V. Sige of Ardale instructed them and their families on resisting demonic influence. The Inquisition arrived in Mawic eleven days ago. The four surviving children who reported no dreams were checked for passengers and cleared. Of the remaining three, two were confirmed free of passengers, but one of those two showed signs of residual tief-dream related corruption; the child's parents were instructed accordingly and V. Sige will continuing observing. The last child had become a tiefling. Her passenger was successfully exorcised and she was cleared. A full report is attached.
Inquisitor Aremmad
Demons and Diabolists
Long before there were mortals, or even before there were fae and dragons, demons warred against the gods and lost, and were banished to the Abyss. They have never forgotten their defeat, and though demons never truly have affection for any but themselves, the thought of revenge alone unites them. One of the few things for which they are organized collectively is thus the task of swelling their ranks. But they aren't content to merely enslave the ghosts of mortals they bind with spell and contract like devils. What they want is for mortals to become demons, and for that to happen, a mortal has to die with their soul already practically demonic, so that at death they simply join their own kind. A demon loves himself first, winning second, and feeling righteous in loving those things third. Demons also tend to be aggressive, cruel (or even sadistic), arrogant, prone to displays of prowess, envious, and spiteful. And mortals can often be like that too, of course, so it isn't hard to find mortals liable to become demons.
But the demons don't just wait for souls to join them naturally. They interact with mortals to various ends (sometimes even just to terrorize them), and occasionally find mortals willing to do their bidding or pledge them loyalty in return for power. Unlike dragons, they don't demand treasures out of reach to almost everyone; unlike devils, they don't demand submission to indentured servitude in the next life. But what they do sometimes demand is human sacrifice, that more souls may join them in their condition. Diabolism is thus the most hated form of spiritualism by the Church, and its Inquisition dedicates considerable effort to stamping it out wherever they find it.
Tiefs
tief - ultimately from Proto-Germanic *deupaz, from Pre-Germanic *dʰewbʰnós, from Proto-Indo-European *dʰewbʰ-. Compare English, deep. 1. deep, 2. (figurative) deep, profound
Suppose you're a demon, and you've got some sycophantic or heavily deceived demonolater willing to offer you human sacrifices. That's not enough to ensure the people they kill will end up becoming demons. Demonhood is a state of mind, and there's little benefit in having your cultists selectively target demoniacal victims, who are likely to end up in the Abyss with you anyway. What would be best is if your cult's victims could be made freshly demoniacal before being slain. And so you must ally with (or yourself be) a tief.
Tiefs are those demons who specialize in the corruption of individual mortals by possession, much envied and grudgingly respected by other demons for their service. When a mortal is offered to a tief (ideally a child, since the characters of children are more malleable), their opening strategy generally involves having the victim put to sleep so that the victim's dreams can be invaded. A tief possessing a dreaming victim can manipulate their dreams, shaping them into a vivid, hyperrealistic false world in which months might appear to pass for the dreamer while only hours have passed in reality. They force their victim to live for months in a fantasy of their devising, made to their specification for warping the character of its audience. First they might instill learned helplessness, forcing the victim to navigate a hellish world in which nothing they do can save them from endless terrors. Then they might throw their now unstable victim into a less harsh environment, but whose comforts are scarce, with others seemingly present with them (mere illusions) whom they must destroy if they are to secure their own advantage. All the while, they are never given a moment's rest to reflect on what is happening to them, so their memories of real life begin to feel like those of dreams, and the dream like real life. And when their victim is finally dreaming of hurting their illusory rivals out of spite, the tief allows the diabolist to finish the sacrifice, and the Abyss gains another soldier.
But this doesn't always work. Sometimes the tief's work is interrupted or the diabolist slain or captured and the victim allowed to wake. And many victims are able to remember their priest's yearly sermon on tief-dreams and either directly resist the tief's manipulations, or retain clear awareness of the dream's unreality and thus prevent their character from being warped too much by what they are forced to do (yet another reason why children, who are less likely to successfully recall such lessons, are preferred). A great many victims are simply too strong of character to let a few months of terrible circumstances, even ones perfectly designed for moral corruption, transform them. Often in such cases, the tief just gives up and cuts their losses. But if a victim presents a real challenge, an interesting challenge that might give the tief a chance to display their prowess in making demons of men, the tief might give up on the tief-dream method, but remain inside the victim's body and ensure they escape being sacrificed. And such a person, with a tief as a long-term passenger, is now a tiefling.
Tieflings
Ever since that terrible night you were kidnapped and barely rescued, something's been living inside your body with you. It's the same thing that was with you in your strange dreams from that night you can only half remember. The village priest says it was a demon. But now it doesn't say anything, or give you weird dreams, or hurt anyone, and you're afraid maybe the Church means well, but might be wrong about your demon. So when the Inquisitors come by and ask you a bunch of questions, you lie, the thing inside you stays quiet, and they let you go. And the thing inside still never says anything, but occasionally you can feel when it pays close attention to something. Those feelings are interesting, because your demon notices interesting things. Maybe one of these days you'll try talking to it. You're not a fool who will let the demon convince you to become crazy like the priest says.
Tieflings are mortals with a demonic passenger bent on manipulating them and the course of their life to two ends. First, obviously, the tief wants their host to become demonic in character before they die, and not live to enjoy redemption. Second, however, tiefs take pride in making their hosts' lives exceptional, especially in ways that display how thoroughly they've succeeded in manipulating the host or in ways that serve demoniacal interests. So a tief wants their host to live a noteworthy life, one that marks history with signs that the demons have it right in their thrasymachian worldview. The ideal for some tiefs is to lead a tiefling to warfare, conquest, tyranny, and success in all these things. For others, it is to guide their tiefling into commerce or crime, both of which permit their own forms of cruel and tyrannical methods. Still others hope to one day guide a tiefling into the ranks of the Church itself, and weaken its moral magisterium from within. Perhaps some tiefs have already accomplished these throughout history and more, and we'll never know.
What powers do tiefs have to accomplish these aims? For one thing, so long as they are not actively controlling the host's body, reacting overtly to pain or distress, or using their powers to manipulate things outside the host, they are undetectable even sorcerous senses. They can also freely speak to their host or otherwise communicate what is on their mind, and they can still manipulate the host's dreams, though no such manipulations can be done without the host's notice, and they always feel exogenous. Finally, they have some ability to affect the physical world around their host. They can use this to make their hosts "lucky" or "unlucky," or otherwise mess with external factors in their host's life, and will often do so if they can avoid detection.
Different tiefs have different favorite strategies with their tieflings. What could not be accomplished with total control in dreams can sometimes be accomplished by letting real life do the work, with nudges here and there to guide the course of events. If they communicate with their host, they'll often admit to being a demon, but put on an excellent show of being courteous, genuinely helpful at times, and overall decent, if slightly cold. These days, a tief who can successfully corrupt a tiefling has to be one who obscures their presence well enough to avoid being exorcised early on in the game, and who can then frame their relationship to their host in a way that obscures their intentions. By the time a tiefling looks back on their life and sees how similar they've become to their passenger, they usually won't mind in the slightest. But getting them to that point requires patience and deception. Demons with a talent for this are rare, and so tieflings are even rarer.
Tieflings and Society
On the Western Continent, the Church knows about tiefs and tieflings, and spreads this demonlore everywhere it can. Priests are required to preach at least once a year on diabolism and tiefs to their parishioners, and the Inquisition with its exorcists is called any time someone is even suspected of having been exposed to demons. Exorcisms are performed for free despite the cost of materials, and the Inquisition's exorcism and banishing spells are quite effective and difficult for most spirits to resist. The church's sermons on diabolism also give pretty good advice. Well-catechized religious folk know that if you find yourself suddenly in totally unfamiliar circumstances after being kidnapped, you might be dreaming, and that you should never listen to voices or feelings in your head that aren't yours. So tieflings in fact are very rare, especially in areas where the Church is strong. Unfortunately, exactly how rare is something the Church can never know, since if a tiefling avoids detection and exorcism, their existence cannot be recorded. There is thus some degree of paranoia in sectors of the Church about the influence of demons (through tieflings) on society at large, but since there's nothing they can do about it, and society doesn't seem to be getting rapidly more depraved, most try not to worry about it too much. Of course, the Church's success in dealing with tieflings just means the tieflings who are around have exceptionally powerful or skilled passengers, so maybe their paranoia is warranted. And in regions of the Western Continent where the Church has become weak, the dangers of diabolism grow.
These ideas are the product of beginning to run Brad Kerr's terrific adventure module, Hideous Daylight, which references demonic child-snatchers (though to avoid spoiling anything for players whose referees might run the module, I won't say in what capacity). This is how I've decided to flesh out why my world faces such problems. Along the way, it turned into my take on tieflings. Other influences include Jim Butcher's novels Dead Beat, Proven Guilty, and White Night.
