A/N: Unbetaed, sorry, not got a beta for this fandom and I decided to post as is to avoid it forever sitting on my harddrive instead.
'Everything is okay.'
He repeated it over and over, first out loud and then in his head, all the while trying to modulate his breathing like he'd been taught. That mantra he knew oh so well, it'd been drummed into his brain ever since his father had first sent him to a therapist for his anxiety following his mother's death. It helped, a little, he guessed. The same way pinching yourself might, a distraction that came in a pattern, something you could ease out of once it became somewhat more true.
It didn't really make everything okay of course, but then the crushing feeling on his chest wasn't actually caused by the current situation. Nothing in particular was wrong, if you discounted the bills piling up on his father's desk and the occasional looks his friends gave him when he said something a touch too cutting, like maybe they weren't 100% sure he was himself. What was wrong was in the past – it was the things he couldn't forget. At least when he'd blacked out before, near the start of it all, there had been blissful ignorance to accompany the gnawing fear of what might be. Once he started to be conscious of what the Nogitsune was doing with him, he started remembering it all and it's those memories that cling to him, those memories are suffocating when he thinks of them.
Part of the problem was that they don't seem entirely out of character when he thinks about it. He'd always been prone to lashing out with sarcasm and laughed with Schadenfreude at certain people's misfortune. Maybe he'd been kidding himself that he was ever a kind person, not with what he really thought. Even though he'd generally thought he was a good person, who tried to do the right thing more or less, with a bit of bending the rules, he knew he cared most about his own and that when push came to shove other people didn't matter so much, he could screw them over in a heartbeat if it meant saving his friends and family.
Plus he couldn't pretend he didn't like playing pranks; he enjoyed the confusion, sowing the seeds of chaos, so overall it seemed pretty fitting a trickster would find a home in him – how much had it even needed to subvert him to do those things, at least when it hadn't been people he cared about? And when it came down to it, when the Nogitsune finally aimed to hurt Scott, there'd been that spiteful voice of his telling him what he already knew, that Scott could take it, telling him bitterly to enjoy seeing those special people around him suffer just like anyone else would, because they shouldn't have it better than others, shouldn't expect life to be so easy when he'd been able to shatter if they'd dropped the ball. That voice said they should have been paying attention, if they had they'd have known, if they hadn't simply relied on him to figure everything out. He'd thought he was the weak point of the group because he was human but the Nogitsune had shown them they were only weak without him because they needed him – it had been so amused to realise what it had taken from them, to realise it before they had, to realise his importance.
The sick part of it was they'd never have been in this position if not for his own morbid curiosity, his glee at the idea of finding half a dead body in the woods years ago. Without that Scott would still be normal, Allison would be alive. But Stiles had never been normal, had never wanted to be normal either and sometimes he'd wanted to be more than he was, not that he liked admitting it. Peter had seen that and so had the Nogitsune. The difference was he could say no to Peter Hale. Sure, Peter had called his bluff, tried to intimidate him like the manipulative asshole he was but he held his ground when Stiles claimed he didn't want the bite because he didn't want someone who didn't want him.
His friends talked about the experience with the Nogitsune as if it'd removed him or replaced him and that's one of the reminders that makes him feel the most guilty – he knows it didn't, he was still in there. It saw the desire he had and took it for its own – it twisted into him by finding places they were the same, filling up the the dark spaces he'd already had until there wasn't room for any other thought. He didn't feel like he wasn't himself when he did what it wanted, because it found what he wanted in the recesses of his heart and prodded at his mind until he fit into its shape - it made itself out of the very worst of him. That's the harsh truth that makes it hard to breath when he remembers.