from a prompt post on tumblr. i'm pretty sure several other people filled it as well, but here's my go at it.
The call had come so very late at night, a time that was the epitome of whimsical and mystical and occult to young boys, that when his father left the house he had insisted on going with him. The man had sighed and scrubbed his hands over his face, and told him that he might not like what he saw. The boy was fine with that, rather he had been expecting it. He was eight and he'd never seen a fire before and there's always a first time for everything, he said. The man relented only because he figured he'd do more damage leaving the boy unsupervised in his home for an hour than any trauma that could possibly be inflicted on his young mind.
So they hurried to the squad car and blazed a trail through the dark of night, deep into the woods. You could see it from miles away, pillars of flame fifty feet high, waves of fire screaming up at the stars, pulsing and raging against the blackness of the sky. No smoke was visible, but it almost surely bellowed heavily into air, camouflaged into nonexistence, only present as a cloying fog the moment you sucked in a breath. The moment he saw the size of the inferno, the sheriff regretted bringing his son. His car skidded to a stop next to one of the firetrucks, and he ran from it to confer with his colleagues, shouting firmly at his boy not to take one step away from where he sat. God what was he thinking bringing his son here?
While Stilinski the elder was busy conferring and staring at flames and shaking his head with disappointment, all the while mentally preparing himself for mountains of paperwork come morning, young Stiles saw something outside of his window that caught his attention rather a lot more than the fire. At the treeline was an older boy, dirty and somewhat singed, sitting flat on the ground and staring at the conflagration with an incredulous sadness. He was alone and he looked terrified. Stiles wasn't quite a genius at this point, but every child knows when another is hurting. It is an aspect of their nature that is equally cruel and wondrous. Of course it took only a single glance for him to realize that the boy was thoroughly wrecked; battered and shattered and fraying at the seams. There wasn't even one thing that could happen that could make this boy's night worse, and there wasn't a thing any adult could do to make him feel better. So, possessing a sound mind and a healthy curiosity and deep reserves of compassion, Stiles made it his mission to comfort him.
He felt a heavy gaze on his back as he climbed out of the car, spun around, and saw that it was the older boy, staring intently at him. Breathing through his nose, tear tracks were the only clean part of a dirt covered face. His face said nothing and his body remained still, but his eyes, oh how they beckoned to the boy. And, as though called from a dream, he ran over to the older boy and knelt beside him. The boy really was older, maybe even big enough to go to the high school, and even once he had plopped himself down, still he stared at Stiles. So the boy performed his duty, one only children of a certain age can truly comprehend the necessity of, and launched forward to throw his small arms around the boy's shoulders.
For a moment there was a tense quiet, then he felt arms slowly encircle him, and heard a gentle sob. Arms around him held fast, forehead found his shoulder, torso heaved and trembled, fingers tightened in the fabric of his jacket, and out of the corner of his eye he saw his father standing by the car and watching with abject exhaustion.
Derek often realized his mistakes just on this side of "far too late". Today was no different. For half a blissful teenage hour, the worst of the scenario was that he'd boned a hot older woman and now she wanted nothing to do with him. Not that he was truly happy with that outcome, but his adolescent male mind supplied him with the sheer burst of ego needed to feel as if it had been a solid victory. He wasn't stupid though.
It only took about a half hour for his brain to remind him that after a one night stand, the owner of the apartment was not the one who was supposed to leave. He pieced things together as he scrambled into his clothing - her smile, a little too feral; her gleeful dismissal of him after he told her about his family, a little too enthusiastic; her desire that they go back to her place, a little too insistent. Finding his car's tired shredded, his heart had sunk even lower, and settled in the deepest pit of his stomach. And so he ran faster than he'd ever run before, his heartbeat ticking like a metronome, telling him he was already too late.
By the time he stumbled into the clearing there was nothing he could do. He'd been able to feel the heat and hear their screams as soon as he had pointed himself in the right direction, and it had pushed him to run, run, RUN. But even the best runners sometimes have the odds stacked too high against them. As he ran he knew there was nothing he could do but be closer to them as they died. He knew in his heart that while he'd been sleeping, basking in afterglow and rolling around in expensive sheets, his family had been burning alive. And there wasn't a shadow of a doubt in his mind that it would haunt him for the rest of his life.
Home he was, and the only heartbeat left was his own. There along the treeline he fell to his knees and he swore he would never move again. And when the cars and trucks with their blinding lights and wailing sirens interrupted his solitude, he scooted back a little further. There was no one he wanted to see or talk to, no one he would be able to show enough restraint not to attack, no one who's neck he wouldn't gladly rip into with his teeth. But then another car pulled up, and something smelled different about this one. Something drew his attention, fluttering little thing with broken wings, and held it. Someone in that car-
He saw the sheriff dash out of it, everyone knew the sheriff. He was a popular man, young and competent and good at his job. Not very tactful, but a good man. Then from the backseat of the car came a small boy. The scent hit him before he got a look at his face. Had he not wanted to stay as close as possible to the pieces of his heart scattered on the ground, he would have shot to his feet in an instant. Warmth and compassion and love rolled off of the boy. There were scents of a more explicit nature as well but he wasn't even remotely prepared to think sexual thoughts about a little boy. Most importantly, he smelled of comfort and of home. He had heard about this in bits and pieces, this was the mate smell. This was his true fated companion. This was the one he was meant to spend his days with, the one he was meant to make a home and family with, this was the one he would always want to run with.
So when that little slip of a thing came up and threw his arms around him, Derek knew he had been right. This fragile human child, weak and vulnerable and so dear to him, was his. Belonged to him, belonged with him. One day they should logically belong to each other, but if Derek could unintentionally kill his entire family then surely he wasn't fit to look after this precious boy, this embodiment of the other half of his very soul.
So he held the child as tightly as he could, and tried desperately to press his scent into him. Frantically tried to ink his ownership into the boy's skin, to make a big enough and strong enough impression of himself on the boy. Work his presence into the boy. Make sure it was clear the boy was taken, was claimed, was protected. He could tell the boy's father was about to call him away, and he pressed a swift kiss to the child's hairline and whispered into his ear "The wolf always watches. The wolf will keep you safe." And as the child beamed at him and ran to his father, he felt like maybe he had something left after all.
