I'll be honest, life on a post invasion Earth isn't easy. Part of it is linked to the part that, since demons can't live on Earth without possessing someone and the Council of Regents, the demons' government, made it illegal to possess a human for more than 5 days in a row, with an obligatory two days cool-down between each possession.
Nothing altruistic in it. Apparently us humans need to regain control of our body from time to time, or we turn insane, which in turn affect the mental health of any demon possessing us. There is, of course, a few exception in which it is legal to possess us for longer, but each overtime day, even partial ones, grant us a week more of cool-down. A—WHOLE—WEEK!
But even then, it still wouldn't be enough for Earth to have its own Regent, who need to be on their domain 24/7, which would force said regent to eternally posses a human, which is illegal and and would be detrimental to their sanity.
All this to say, few kids have the luxury to stay innocent for long, even the ones with two parents that live rather comfortably for humans like I was. So when the obligatory test revealed I could be possessed without adverse effect on my body I already knew in which school I wanted to go, all 11years old I was. Demons had long ago built portals that let living human go to Hell and back, but you can't go through them without authorization.
In the old world, before the invasion, peoples imagined Hell to be nothing more than fire and brimstone, from what I read. And while a part of Hell is like that, it's far from being the case for all of it. Among the multiple environments you can find in Hell, there is all the one you can find or used to, on Earth.
Most of the other kids in my situations try to go in a seemingly pleasant place, but the schools in those place can accommodate much less students than the ones wanting to go there, so they have very strict acceptance criteria and all the refused kids get haphazardly thrown in less enviable environment, the kind in which they're forced to stay indoor to stay alive.
For my part, I choose to look at which of those school lost in inhospitable environment had the best reputation and curriculum, and choose a place so cold even nitrogen was frozen solid. Sure, I wouldn't be able to go out without being possessed, but I would have a good education, be given a place in priority over the one send there because they got rejected at the school of their choice and even gain some goodwill from the teachers there, for having chosen a place so inhospitable.
What I hadn't calculated was how resentful most other human kids would be because of that. It made making friends rather hard.
In fact, I didn't make any until my first possession. It only lasted for a few seconds and was part of a lesson about being a good host, a couple month after my first year in hell-school started. Where most negotiated to try to be with a mostly humanoid demon of the same sex than them, I accepted to let a gelatinous demon posses me.
Fenk was a blob-like demon from another realm able to secret all kind of poisons. Like me he choose this school for its academic might.
I won't lie, turning into a genderless purple blob was strange, but at least it wasn't painful. The cries and pained grimace on the others proved the transformation induced by a vertebrate demon possessing you was more hurtful.
Once the possessions ended, the teacher asked "Do you know why most of you were in so much pain?" When no one answered, he did so himself. "Because the humans present were never possessed before. With time their body will get used to it, making the process a painless one. But they still are a few possession away from it."
Curious as to why I didn't feel pain too, I put my hand up. Once the teacher told me speak, I asked "In that case, why didn't I feel any pain?"
"A very pertinent question, young man! For an unknown reason, being possessed by an invertebrate demon is never painful, even if its your very first time."
After that, the teacher let us discuss our feelings about that first possession between classmates. Like usual, the other humans snub me, but other demons came to discuss with me, including a hellhound, who asked if I was okay to be his host next time, despite the pain. "Why not. After all I'm destined to be possessed by all kind of demons, the sooner I get the habit, the better."
Then I noticed a demoness, some kind of devil, being ostracized by her pears like I was by mine. "Hey, who's the sad demoness all alone?"
"That? It's Crystal, a succubus. You notice how she's the only one with wings on her back? It's because she's a direct decedent a fallen angel. Her ancestors were Royalty, then they fucked-up and we created the current system with the Regents. She is an orphan born long after said ancestors had been replaced, but most of my kind only see her wings and judge without taking the time to know her."
"Not you, evidently."
"Well, the girl saved my life a few years back, putting her own in the line. She didn't have much to gain doing it, and even refused any kind of reward for it. That commands respect. Do you want me to ask her to join us?" At my nod she called "HEY, CRYS! COME HERE!"
Crystal timidly came near with us before speaking almost inaudibly. "You shouldn't call me like that, you know Wulee, the others might pick on you now. Maybe if I go now they'll think you had some disgusting remark to do you didn't want the teacher to hear…"
"Crys, you saved my life! You gained my respect. And if those jerks have a problem with it? They can kiss my fluffy ass!" Loudly interrupted the quadrupedal demon.
Seeing Crystal from closer, I could notice that her legs looked mostly human. In fact, only her feet were less than so, and mostly because she only had two toes that made said feet look like cloven hooves with sharp ice instead of keratin. I would latter learn she had a third sharp digit where a human has their heel, making those appendages talons rather than proper feet. Her hands were more human like, although her digits ended, like her toes, in sharp ice-looking claws. Her skin was in an Asian-like color. The skin of her bat-like wings was the same color, but I didn't know how strange that was back then. Said wings had a total of 7 digits. Between her wings' thumb and the usual 4 digits that help stretch the skin into a proper and perfectly usable wing, she had an index finger and a middle finger very similar to the ones on her hand. Her cat-like eyes were ice-blue, as were her hairs and, surprisingly, she didn't have horns.
Crystal sat beside us and, nervous, started to ‘play’ with her tail. That's when I noticed it ended in some sort of blade that, like her claws, looked like it was made of ice.
I extended my hand toward the young succubus and presented myself. "I'm Vivian."
"Crystal, but you can call me Crys' if you want." She said, Ignoring my hand.
"So, what did you think of this first possession?"
"Painful. I don't want to inflict that kind of pain to anyone else. And you?"
"Loosing control of your body is scary, and feeling it turn into some kind of jell-o is strange. But I suppose its the kind of thing I'll have to get used to. Say, I know I already promised my next possession to Wulee, but do you want the next after that?"
"You would go through being possessed by girls twice, without being possessed by a boy in between?"
I… Hadn't realized the hellhound was a girl.