Obsession

A/N: It's been a year now since I posted my first Sterek fic and it's been too long since I last posted any Sterek at all... So here we go. I was inspired and that's where this came from. A big thanks to Gen for putting up with my constant and random messages regarding this one shot. Hope you enjoy... and also, hopefully I can get working on some more of my Sterek fics soon.

Warning: Spoilers for Season 3

Disclaimer: The characters don't belong to me, I'm just playing around with them.

At first, it's nothing. Then it's a constant itch at the back of his mind that has him pacing the loft floor, stalking back and forth through the shadows with his hands clenching and unclenching again and again. The temptation to strike out has him so on edge that when he pivots to retrace his steps yet again and finds himself face to face with Isaac, it's only the young werewolf's quick thinking and reflexes that saves him from having his chest slashed open.

Isaac's eyes widen, but he doesn't seem worried. If anything, there's a tiny amount of amusement in the lines of his face. It isn't that he doesn't think of Derek as a threat. He just knows Derek is distracted and that gives Isaac the advantage. For now.

"She got you good," Isaac says when he straightens and gives Derek the once over. Derek doesn't care. He only has one thing on his mind.

"Where is he?" he demands, hands forming fists and nails digging into his flesh in the hopes of keeping just the tiniest amount of self-control. He holds himself as still as possible and his muscles twitch as he fights the urge to carry out the threat that somehow settles in his words.

"Safe," Isaac says, and he takes a step back, amusement disappearing from his features. He can sense how bad it's gotten and he knows this isn't good. It isn't just a joke anymore. Somewhere, buried deep inside of Derek's thoughts, he knows the same thing.

"Where?" Derek forces out through gritted teeth, and he can't control the way his eyes take on a dangerous glow, or the way the normal softness in his voice is replaced by a low growl.

Isaac immediately blocks Derek's path to the doorway, arms spreading out just enough to visibly deny Derek access, even though Derek makes no movements to head that way. Didn't mean he hadn't thought about it.

"You know I can't tell you that," Isaac tries to reason, and Derek can hear the way his heart speeds up, and smell the fear as Isaac realises he isn't going to be enough to stop Derek when the time comes.

Maybe they should have gone for the chains after all.

Derek just breathes heavily in response and feels his control wavering. He feels himself slipping, giving in when he should keep fighting.

"Derek!" Isaac snaps, and Derek pulls his gaze away from the door to look at the young werewolf instead.

Swallowing hard, Derek closes his eyes tight. "It's getting worse."

"I noticed..."

And damn it, where is his uncle? What is he playing at?

Derek only has so much self-restraint left and that is almost all gone. The witch's curse had hit him hard, so hard it had literally knocked him off his feet and sent him flying backwards. She had well and truly whammied him. Whammied...

"Uh, guys... I think she whammied him... I think Derek's been whammied!" Soft hands, tapping his face with increasing strength until he finally opens his eyes to find himself staring at amber orbs and pale skin and freckles and wet hair that had been flattened down due to the heavy rain.

"Stiles," Derek breathes out, and he almost loses it there and then.

Heart racing fast. Warmth spreading throughout him. After effects of the spell...

"Woah, easy there, Buddy... don't wanna strain yourself."

"I'm fine."

"Really? You're fine? You just got thrown back and whammied by a high-freaking-priestess but you're fine."

"Stop. Talking."

Isaac's voice washes over him, but the words lose all meaning and all he can hear is the fear and the doubt. There's a small part of him that wonders if the curse wouldn't have affected him as badly if he'd only had to deal with the crippling obsession, if he hadn't had to control the wolf too... if the witch hadn't chosen to come to town during the full moon.

"Derek? Are you... Guys! Uh, guys?!"

"Stiles... run."

"Find Peter," Derek forces out, only partly aware of the order slipping past his lips – the other part of him already contemplating how best to tear Isaac apart. "Find my uncle..."

Isaac's face drains of all colour. "I'm not supposed to leave you alone."

"Isaac," Derek growls out in warning, and he hopes it's enough. His nails are already lengthening into claws and he can't keep a hold on himself any longer. His restraint snaps. And that's it.

He lurches forward, but Isaac is already moving. The younger werewolf reaches the door only just in time to slam it closed in Derek's face. Metal clicks into place, and no matter how much Derek slams into it, it holds for now. But only the smallest part of him feels relieved, the rest of him is frustrated. He's a caged animal, but he only desires freedom for one reason and one reason alone.

"Why Stiles?"

"Hey, I'm right here, you know?"

"If I had to guess, I would say it's like the effect between a baby bird and its mother."

"Stiles was the first person Derek saw..."

"And so Stiles became the object of the obsession."

"How do we fix it?" Low, almost a growl. The ache in Derek's chest fast becoming unbearable.

"We don't. We either let it run its course, or she breaks it."

"And in the meantime?"

"I suggest we keep the two of you apart. As far apart as we can."

It feels like a punishment. Instead of waning, the curse just gets stronger. The hunger builds in Derek and he's restless to the point of considering the large open windows of the loft as an escape point... a way to break free and leave in search of Stiles. The loft had been designed to keep others out, but a few changes later and now it keeps him in, the door locking from both sides.

He doesn't need to, but he locks his side just in case and leans against the heavy metal, leans into it and breathes in deep. How weak is he that he can't even control himself? How weak is he that a witch's spell is all it took for him to go tumbling over the edge?

"Stiles!"

"Derek, stop! Stop!"

"Get him out of here, now!"

His teeth grit together and he turns so his back is against the door, his head crashing backwards into the metal, but the dull pain does little to distract him. He's never felt so consumed in his life. His skin crawls and his blood burns, and it isn't long before he finds himself thinking of other ways to escape. The door isn't the only way in, or out. The fall from the windows could kill him, even with his healing abilities, but the desperation creeping in has him considering it as an option anyway.

He closes his eyes and focuses on his breathing instead. Counting each inhale and each exhale, using it to try and steady his erratic heart rate. It does nothing. His heart still races on and he slams his head back once more. He's about to do it again when he hears the metallic clank of the outside lock falling away and he pauses instead to simply listen.

"Isaac?" he questions the silence that follows. "Isaac, you have to find Peter. You have to help him break it..."

But the response that follows isn't what he expects.

"Derek... It's me." The door handle moves but the door doesn't budge, still locked tight from Derek's side. "Open the door, Derek."

"Stiles?" he says the name like it's both a question and a prayer, breathes it in like it's oxygen. "Stiles, what are you doing here?"

"Saving your ass. Now open the door, Derek."

He wants to. Almost finds himself turning around to do just that, but he has enough left about him to keep his hands away from the lock. "Where's Scott?"

Silence...

"Stiles, where's Scott?"

"I ditched him just outside of town, okay?"

Derek curses and bites down the insult before it can make its way out. "You have to leave. Now."

"I'm not going anywhere."

"Stiles, I could kill you!"

"Or you could let me in..." There's an edge of panic to Stiles' voice there that Derek picks up on, his tone urgent. "Like, right now..."

It's when Derek hears the rush of footsteps and Scott's voice that he understands why.

"I'm not afraid of you, Derek. Now let me in."

And he knows, he knows that if he just holds off for a little longer, that Scott would be there to drag Stiles away, and at least some of the temptation would leave with him. He knows. He knows... and yet he still unlocks the door. His hands still wrap around the metal and tug at it until it's free, and the door swings open in response.

Stiles comes tumbling in and slams it back into place immediately, just as Scott slams against the door from the outside, but the young wolf's cries are drowned out by the sound of Stiles' heartbeat in Derek's ears. It almost cripples Derek. The sound, the sight, the scent... all of it Stiles. The one person who shouldn't be there. The one person that was supposed to stay away until they found a cure.

Derek inches forward, his gaze roaming over Stiles and drinking him in. It's only when Stiles turns around, his face a breath away from Derek's, that Derek realises how close he's gotten, and watches as Stiles' eyes widen as he realises it too. There's fear in those amber eyes, but there's resolution too, and when Derek crowds him, Stiles pushes himself as far back against the door as he can go in response... which isn't far at all.

"You shouldn't be here," Derek says, and it should be a warning, but it's low and husky instead. Hungry. His fingers move up until they come to the ripped collar of Stiles' shirt – the flesh beneath it tainted red from the dried on blood that had long since stopped flowing from the scratch marks marring Stiles' neck.

Some of that same blood still sits beneath Derek's nails. But that was before... when they hadn't been alone and when Stiles had tried to run. Now, it's just them and Stiles isn't going anywhere.

"Listen to me, Derek," Stiles says, words slow and careful, Adam's apple bobbing in his throat, drawing Derek's attention to the movement of it... to the way Stiles' neck is right there and the way his skin glistens from the beads of sweat dripping down it. "You don't want to hurt me..."

Derek doesn't answer. His hand just hovers over Stiles and it's like the air is filled with electricity. It isn't restraint that holds him back now... it's knowing he has all the time in the world and no one to disturb him this time.

"Yeah, that's right," Stiles continues, confidence lining his words despite the quiver that sits beneath them, "you want me, Derek... and I'm right here. I'm right here..."

Gaze flickering up to meet Stiles', Derek pushes closer. But he stays silent. There's nothing to say. Except, Stiles doesn't seem to think that way.

"You see, I figured it out... When Scott was first bitten, he refused to accept it... He was so afraid he couldn't control it that he wouldn't control it. And maybe I'm just reaching, maybe I'm wrong... but this Sabrina the teenage witch, she doesn't just create stuff from thin air. The pteranodons, the giant man-eating tree... she just took what was already there and embellished it. She breathed life into them..."

But the words just wash over Derek. He's too busy focusing on Stiles' lips and the way they move when he speaks. He's too busy losing himself that Stiles' next words are like a jolt that brings back only the briefest moments of clarity.

"You like me, but you're too freaking scared to admit it. You're too afraid to admit that there's something there, that you feel something... and that's why you can't control it. Because you won't accept it."

"Stiles..."

"I'm right here, Derek. I'm right here, and I'm not going anywhere. I'm not afraid of you."

Derek's barely aware of the way his fingers wind their way into Stiles' shirt or the way his gaze lowers, unable to look Stiles in the eyes, even as he can't tear his attention away from the steady thumping of Stiles' heart. He's barely aware of how his own breathing slows to match Stiles' or of the fingers on his neck, pushing his head back up until he finds himself looking into Stiles' face once more.

He wants to push away, wants to tell Stiles' to run, but the way Stiles' tongue flickers out to wet his lips and the way he swallows thickly and his own gaze dart's down to Derek's mouth for the briefest of moments... Derek can't say anything. He can't do anything but act on instinct.

He surges forward until he can no longer just see and smell Stiles, but feel and taste him too. Soft lips, frozen only momentarily by surprise, begin to push back. Nails scrape across his skin before fingers grip tight at his shirt, and that just makes Derek push harder and closer. His own hand moves up, fingers weaving their way into the mass of hair Stiles had grown out over the summer.

It's when he hears the light gasp for air that he realises where his other hand has wandered, slipping beneath Stiles' shirt to slide up his back... warm skin against cold. The contact causes Stiles to press forward and Derek mimics his movement until he can feel Stiles' chest against his, deepening the kiss and driving further into it, fire spreading through his veins at the overload on his senses.

"D-Derek," Stiles tries to say, breathy and raw, but it doesn't sound like a protest.

"Stop talking," is all Derek says in reply before claiming Stiles' mouth and breath again. No more talking. No more running. No more being afraid. And judging by the way Stiles' body reacts, Derek knows he agrees. Judging by the way Stiles doesn't pull back but instead grasps on even tighter, Derek knows he's not the only one whose mind has been assaulted by a constant itch it couldn't scratch... until then.

Thank you for reading!