I reckon Dementors are what people become after a few centuriesnof immortality having drank Unicorn blood. I imagine it was all the rage when people first realised it made you immortal (hence unicorns being so rare to this day), but after a while the curse caught up with them. The light bled out of their lives, all the magic they attempted went wrong, caused damage that ultimately had them driven from their homes and lives, and they were miserable. Constantly.
The phenomenon was tested, and eventually it was discovered that the ingestion of even the smallest amount of unicorn blood caused the soul itself to erode. That was the curse, the half life. You lived forever, but you didn’t get to keep your soul.
The longer these people lived, the more twisted and less human they became. Soon the world wasn’t only colourless, but completely invisible. They’d gone blind, as well as deaf, but their lost senses were made up for in other ways. They could feel the emotions of people—real people, not what they’d become. Vicariously, they were begining to feel human emotions for the first time in hundreds of years. And they were hungry for it. In droves, these bare shells of humans would descend on towns and villages only to stand around people’s homes, black robes hanging over their impossibly skeletal frames, moaning and wailing, guttural perversions of voices that often drove the victims of their presence to madness.
Hence the name Dementors.
It was then that the first of them recalled how they’d come to be this way—the power of the consumption of blood. How pure and invincible that first gulp of unicorn blood had been. Of course, it had turned out to be a terrible, terrible idea, but but then they’d lost all sense of morality, of right and wrong. All they cared about was the possibility, the slimmest chance that they might get even the smallest taste of that again.
It was then that the first Dementor followed a young man on his way home into the darkest stretch of road and sank his teeth into his throat, drank his blood until the body was drained dry of it.
And it worked, in a way. Consuming the life-force of a human being was powerful, certainly, but emotions didn’t run in blood. It wasn’t where the feeling hid.
None the less, killings became more and more common after that, the new knowledge communicated without sight or sound between them. But they wondered how they could get a more powerful high still, and thoughts returned to the essence of their condition—the essence of themselves.
Their souls were rotten. Perhaps… perhaps if they could take the souls of the living…
So they sought means to do so. It was terrifyingly easy for them, to do something so terrible, warped as their magic was. And the more souls they consumed, the faster and faster their last vestiges of their humanity left them.
So many centuries after their fatal (or rather the opposite of fatal) errors, the Dementors were no longer recognisable as having ever been human at all. They no longer walked along the ground but drifted through the air, ominous like shadows caught in the wind. And souls became all that they fed on—particularly the happy memories that lay there. Because though they could no longer remember that they had once been people, that all they’d wanted was for light and colour and joy to return to their lives, some intrinsic part of them followed the instinct all the same—sought happiness even if only stolen, because they were no longer capable of feeling it themselves.
And that kids is why we do not drink the blood of unicorns.
