Dementor, the name itself implies some sort of malignancy. The humans force us to guard a prison, they stick us with the worst of the worse, and, quite frankly, we're insulted. We can't exactly fight the power when they can use magic and we've not yet evolved a defense mechanism against it, so we make due with what we're given.
We are, if anything, scholars in our own right. Psychologist. Born with a curiosity for the workings of the mind. Our minds, human minds, complex minds that give us a challenge, that make us think and ponder and give us something to do.
Our existence, without this fascination and discoveries for the common good(that no human will ever bother to listen to), would be rather useless, considering that we don't have a significant in any food chain, we don't die either, we just drill any souls we've kissed on the life and goals of dementors when our minds start going foggy, get them brainwashed and let them take over once your soul disintegrates. We mate by giving any extra brainwashed souls to fire crabs on their deathbed, hence all the mist. When the fire crab itself dies, it curls into it's shell and the clammy body starts metamorphosis, once it gets fingers it starts shredding the inner lining of it's shell(an adaptation to prevent chafing, it's very soft, silk like) to make our patented Floaty Garb of Impending Doom!(copyright Dementors Nabmiol(what one calls a group of dementors, if being politically correct) since 1,267,237 B.C.) Other than recycling crabs, we do nothing important.
Contrary to popular belief, we dementors are some of the most compassionate and empathetic creatures on the face of the planet. We can't help it that happiness is so necessary to our daily nutrition. If I could eat sadness I would, but I can't, it would be like asking the Earth to stop rotating so you can work on your tan all night, which would be rather inconsiderate to certain nocturnal animals with sensitivity to light, or people on the other side of the planet who can't start their day until they can see what their doing.
See? Always looking out for others, us dementors. It's one of those under appreciated traits of ours. We only kiss because we care, those prisoners are practically begging us to within a week. We put them out of their misery and they're better off for it. I know this for a fact, deep insight into the way you humans work is one of our special talents, comes along with the whole "make you relive your worst moments" side effect of our snacking. If we've kissed then the souls we've been carrying make good research, though, I'll admit, they tend to be a bit crazy. With unlimited access to their memories we've got an idea of what drove them to their unspeakable actions and know how they thought it justified. We usually only get glimpses into the minds of non-psychopaths, so our views may be a bit biased. Sorry about that.
Our bias is not that bad though, we get the occasional innocent person, far more studiously psychoanalyzed than the run-of-the-mill murderer. Breath of fresh air, really. Whole new perspective. They usually don't last as long though, we like to be thorough with different cases, since we already have the gist of the average villain. Overexposure gets them, it's shame, too, because it breaks a dementors heart when the lives of good people end just because the cats got too curious. It's more curiosity than hunger that forces us to feed, when we get close enough we are met with the memories and thoughts we want to know about, but end up inadvertently draining them of positive emotion. It's a way of making sure we're fed whenever possible, to eat using proximity alone. It's through eating that we learn, it's our thirst for knowledge, not the need to feed that makes us swarm.
That's probably the reason why Sirius Black is such a legendary figure among the dementors of Azkaban. He's our longest lasting prisoner ever, for one thing, he's innocent and we didn't kill him, he escaped us(and though most of us miss his company and pretended to be outraged, we were actually quite proud and knew his intentions upon leaving, and let him anyway), he withstood our constant curiosity and feeding with aplomb, and having been the only prisoner ever to be there long enough without going mad to be bored, was our only other source of entertainment, for indeed, he thought some amusing things in those twelve years with us, whether he thought it was funny or not.
When he escaped, we all liked and respected him enough to not want him caught, to not want him kissed. The ministry made us go after him with their evil magic, this type of thing is the very reason we vied with Voldermort, he encouraged us to do what we want and never used magic on us. Of course, he figured our intentions were as wicked as his, they weren't, but respect means a lot to us. He treated us like equals, the ministry treats us like obedient watchdogs. We absolutely hate it, so naturally, having learned the art of mischief from Mr. Black himself, we purposefully looked in all the wrong places and went places we weren't supposed to, under the safety of the notion the humans had that we were simply being dutiful and looking for Black.
This was also our only chance to get out and about and learn about a greater range of people than lawbreakers and innocent people accused of breaking laws, there was the occasional guest, but they were almost guarded by a Patronus. One time someone came to visit Sirius without one, having realized he was friends with this guy, we all swooped in for a better look. He never came without one again. We never learned anything else from him, or any other guest.
It's a less varied range of humans than we'd like, and by rebelling when our authority figures chalked it up to increased work ethic, we got to learn more than ever, and they weren't willing to restrain us enough to make us stop, just in case we were on to something. It was the best year of our lives.
We're glad he escaped, because if one of us had been forced to kiss him, they'd probably die of guilt, or once their soul disintegrated, be regarded as a god and offered sacrifices and coloring books and crayons, the secret treasure of the Dementors of Azkaban, that only the all-powerful have the freedom to wield, dementors only, or we'd have offered it up sooner.
It was a grave day for us when an escort from the courts in the ministry caught wind of Sirius Black's death, something we thought wasn't even possible after he survived so long in Azkaban. We were fairly outraged when we realized he was killed by a curtain, but it was quickly replaced by widespread mourning. A species-wide memorial holiday is observed every November first to commemorate the day we came to know our favorite human ever, and the whole month of June is spent mourning his death and burning drapery with the help of our comrades, the fire crabs.
In conclusion, although we're considered soul-sucking, evil beings without a shred of remorse or rational thought, we burn drapes to honor heroes and have ambitions and think and grow old, we spend ours lives studying and doing what we must to not be slaughtered by evil wizards. Us dementors are just like you humans, except we dress better.
***
Like the slugs, it came to me in the middle of the night, dementors as well-meaning scientists that reproduce using dying crustaceans and hero-worship Sirius Black. That value coloring books and crayons above all else. Insomnia doesn't suit me. I now see dementors in whole new light. Argh.