His Reason: (by timydamonkey)
Disclaimer: I own neither Harry Potter nor Shin Megami Tensei: Nocturne (or Lucifer's Call as it's called here in the UK). I make no profit from writing this fanfic; I'm just a fan.
Author's Note: Yes, I'm aware this is one of the most bizarre crossover ideas ever - but I started seeing some parallels between a few characters, and thought I'd like to explore that eventually. This isn't really an action story, though - keep that in mind.
If you don't know anything about Nocturne, don't run! You're quite welcome here. If you need to ask, do so - I'm a point of view writer, so I can't, for instance, have Isamu start reciting the definition of magatsuhi. He knows what it is; he has no need to commentate on that. Hopefully I'm giving enough info, though.
The story so far is set in the middle of Harry Potter and the Goblet of Fire for HP, and after Isamu goes into the Amala Network (but before he gets those creepy faces on his chest) for Nocturne.
Sorry, the beginning of this story has a fair bit of exposition (wait until you see the amount of exposition trying to creep into chapter 1... damnit Hagrid!), but hopefully this'll die down when everything is contextualised and I'm not writing from a character POV for the first time.
Oh - and I'm using Naoki as the demi-fiend's name, since that's the closest we have to a default.
Prologue:
Isamu's eyes struggled to adjust to the gloom. Inside the Amala Network, everything glowed an ominous red, the very air alive with life – or maybe with death, with all the souls floating around in there. And they, he thought humourlessly, were the tame ones. When he closed his eyes, he saw a red shimmer dancing behind his vision, twirling around, trying to entice him back under its spell. He breathed in there, and his breath went away.
Pure power. The demons felt it too. He'd heard them whispering (magatsuhi, magatsuhi) while he hid behind corners, anger and helplessness raging through him. He'd already been in prisons, at the mercy of merciless beings, twice now. He had no desire to make it a third time for crimes never written in any rule book.
These demons just did what they wanted. Humanity didn't matter to them.
But the magatsuhi intoxicated him to the degree where he couldn't think, him clinging to the edge of sanity (of humanity), and that wouldn't do at all. He needed some space that wasn't crawling with demons, where he could think rationally.
He could shape the world. That voice had told him so when everything outside of that hospital ceased to be. He could call it a prize for being human in this hell. He could count the humans he'd heard of on one hand, rare prizes among the demons itching for a war he didn't care about. And then there was Naoki… who knew what he classed as anymore. The germ of an idea, of a Reason, was sprouting in his mind, and he wanted to nurture it before it withered away in the wake of distractions.
He'd done it. He'd activated the terminal by himself, he could do everything by himself, he didn't have to sit around and wait to be rescued (and be last on the agenda). The accomplishment made him smile a slow, delighted smile. He had power. He had brains. He didn't need people to believe it (there was nobody left to believe it), he just needed to know it himself. He hated the Vortex World, the way everybody tried to press their values on to him with orders but it didn't have to be that way.
He remembered Thor seizing him, the feeling of loss when he awoke, barely able to move. ("Magatsuhi," his neighbours had said then, and it turned out they weren't humans at all, just some bastardisation of humanity. "They're taking our magatsuhi!" Even though he hadn't known those words, even though they made little sense, he knew it was true. He felt it.)
Now he'd found another terminal. He suspected it had been dormant for a long time; even the demons roaming the Amala Network didn't seem to have found it, and it wasn't humming like the other terminals connected to the network. This one was his own discovery, an ancient-looking relic and a personal triumph.
He activated the terminal, and curiosity led him through. He held his breath, terrified that activating it would summon something else, but nothing came. Apparently the demons couldn't feel the network like he did. They just followed the trail of magatsuhi; the terminals required human understanding. He hoped.
The air seemed thickened with dust, the room almost tomblike, and perhaps that would have bothered him a few short weeks ago, before there were other things to worry about. Now, it just felt familiar, and deeply satisfying. The world was silent. He was alone. There were no demons.
The terminal stood still behind him, looking dead, but now it was thrumming with suppressed power. He felt an echo of a call in his veins. This foreign magatsuhi, twisting him from the inside. In this primal world, magatsuhi meant power, and it was apparent he didn't have enough of it to survive encounters out of pure luck any more. Isamu knew that he couldn't traipse in the Amala Network forever, that the need for moremoremore would forever be pressing at him. He needed a larger amount of magatsuhi, and quickly.
In this room, he could think like a human, not survive on animal instinct. It was a welcome blessing.
The room seemed to be empty other than the terminal, or at the very least, he didn't trip over anything as he groped for the wall. He felt little calluses in the wall with his hands, the rough stone showing the signs of age. He wondered where he was.
His hands brushed against something different along the wall, knocking something lopsided. He heard a scuttling sound, and something that could have been a gasp. He spun around, eyes open to find any sneaking demons, but he still couldn't see anything. Maybe it was rats. Such petty human concerns didn't bother him anymore. He moved back to the object, and decided from feeling around the edges that it must be a picture of some kind, albeit a large one. He didn't bother to try and right it, since in the dark he'd have no idea how it was supposed to be. He just moved on.
Nothing else was in the room.
Isamu frowned. He couldn't stay in such a place in the long term. The room wasn't very large, and while he'd never been especially claustrophobic, he felt he was entitled to want to be able to roam after spending so much time trapped in cells where there was no such thing as morals. Cruelty wasn't just acceptable; it was expected.
(When he closed his eyes, he could hear the screams of the manikins as the magatsuhi was ripped from them. Not all survived the continual harvesting. He'd seen it, and thought it would be him next.)
It was a shame; the location was otherwise quite ideal. He was sure he could find one way or another to adapt it to suit him, but for now, he'd recover from the effects of the Amala Network, and then he'd re-enter.
When it came down to it, it seemed human was just a word. He craved magatsuhi as much as the demons did, and he'd feed that desire too.
In a rare place of rest, he leaned back against the cold stone wall and closed his eyes. There was nobody there to watch him remember.