He wasn't sure how it had happened. It's not like he made a habit of looking at Stiles' mouth. Sure, he had thought about duct taping it shut on several occasions, but who hadn't, right? So it took him quite by surprise when he found himself fixated on the way the boy's lips were wrapped around the end of his pen.
He was hunched over his desk, a chemistry book and notebook spread out before him, and every now and then he would remove the pen from his mouth and jot something down before biting down on it again. Sometimes he would make a face that indicated he was confused, and sometimes he would get this stupid grin that told Derek he had just figured something out. He'd even laugh to himself as if he was a grand master of all things chemistry and was amused by such simple work.
It was incredibly annoying. And horribly cute.
Derek flipped a page in his book even though he hadn't actually read anything. He was playing guard dog over the human boy while Scott stayed with Lydia, and Isaac with Allison. The new pack that had come into town was vicious, eager to lay claim to the territory by coming after the resident pack. Scott had refused to step down from the fight and as a result their alpha had started targeting humans. Scott's humans -Derek's humans.
The former alpha had offered to look over Lydia and leave Scott with Stiles as it was the obvious choice. But Stiles was studying for the SAT's and was adamant about not being distracted. And as much as Derek didn't like it, even he had to admit that if Scott had been the one to watch over him then there would have been exactly zero studying. And they'd all have had to listen to Stiles bitch about it later.
So here he was, sitting in the corner of Stiles' bedroom, pretending to read a book, wishing he was somewhere else, and sneaking too many glances at Stiles and his stupid pen and his stupid mouth.
He flipped the page again, this time almost tearing it from the book.
Stiles lifted his head and looked over at him. "Dude, easy on the book, it's from the library and I am not paying damage charges on it if you wolf out and tear out all the pages."
Derek shot him a withering look that made Stiles roll his eyes before turning back to his textbook. He glanced at his phone. It was only eight o'clock. How was it only eight? He was sure he had been sitting here for longer than an hour. And how long was Stiles going to study? He wasn't sure how much more of it he could take, not with the way he was biting the end of that pen with his brow furrowed in concentration in a way that was too adorable. Stiles wasn't allowed to be adorable.
Stiles was loud, hyperactive, obnoxious, noisy, stubborn, and talked far too much. He wasn't supposed to be anything else, especially if that something else made Derek like him and want to look at him.
Derek hated wanting to look at people.
It always led to him wanting to talk to them, hold their hand, and kiss them. And it all inevitably led to him being betrayed by them. And while his mind was certainly not taking that course of thought in regards to Stiles (no, he was not think about the warm weight of Stiles' hand in his or the way his lips might feel on his own, absolutely not) he still didn't like wanting to look at him.
But he couldn't seem to stop. He couldn't remember ever being so fascinated by someone chewing on a pen before. It was a gross habit, really, and something Stiles should probably stop doing.
Derek watched helplessly as the brunette sucked on the pen cap while contemplating an indecently long formula. The werewolf had to repress a shiver at the sight of his lips clamped firmly on the plastic.
He never wanted Stiles to stop doing that.
But he definitely needed him to stop. Right now. Immediately.
For a moment he thought about calling Scott and demanding he switch with him, but knew that he would have to explain his reasoning. And there was no reason, not one that he was willing to admit to. Other than the hellish pen sucking Stiles had been perfectly fine since he had arrived. He'd chatted a bit when Derek had climbed through the window but had been too focused on his studying to keep up his usual stream of verbal vomit.
No, he wouldn't call Scott. He would stay right where he was for the entire night and keep the human safe, just as he said he would. Despite his tendency to be utterly annoying, Stiles had proven himself invaluable to the pack on more than one occasion. Derek owed it to him to make sure a psycho alpha didn't come through his window and kill him. Well, at least one that wasn't him.
Stiles bit the pen again.
Derek stood up abruptly, tossing the book onto the chair. "I'm going to get some water."
"What if a werewolf jumps through my window while you're downstairs and I die because you were too busy refreshing yourself?"
Derek raised his brows. "Would you like to accompany me to the kitchen?" he asked in a way that suggested if he were to say yes it would not end well for him.
"No but I could use some water too while you're down there. Grab me a bottle?" Stiles gave him a bright, innocent look that made Derek want to hit him. Or kiss him. No, he reprimanded himself, hit him.
He left the room with an annoyed huff. Luckily the sheriff was on duty so he didn't have to worry about any awkward conversation while he retrieved the bottles of water and tried to get a hold on himself. He wanted to hide out in the kitchen where he was safe from Stiles and his pen, but he knew if he did then Stiles wasn't safe. And then he might not ever see him again. Which at the moment sounded like the best and worst thing in the world. He sighed, running his fingers through his already mussed up hair, and went back upstairs.
Of course it became quickly apparent that giving Stiles a water bottle was one of the worst things he could have done for his own sanity as now the boy had two weapons with which to torture him. He switched between chewing on the pen and taking gulps of water, his lips around the bottle opening, his Adam's apple bobbing as he drank. Derek was alarmed to find his pants feeling tighter than they had before.
This was getting out of control. How could one infuriating human boy turn him on so much? It was completely uncalled for.
Derek closed his eyes and took a few long breaths to try to calm himself down. And then he pulled the chair over by the window so that he could prop his feet up on the sill and not be facing Stiles, who was watching him with interest.
"I think you're taking this job a little too literally," he joked. Derek just waved a dismissive hand at him, not turning to meet his gaze in fear that his body would betray him again if he looked at those lips one more time.
He opened the book again and attempted to read. But the words just sat on the page in front of him, mocking him with their refusal to distract him. He almost hoped a werewolf did try to climb in through the window and attack them. Then at least he would have something to do. Instead he just sat with the book, flipping the page every few minutes without reading anything, and tried to stay calm and collected.
When he heard the subtle sound of Stiles sucking in the pen cap he had to take a deep breath through his nose to steady his overactive hormones. This also proved not to be a good idea as he also inhaled the boy's heady scent -a mix of grass and a spicy musk that was his cologne. Derek felt his pants tighten again and he cursed quietly under his breath.
But not quietly enough.
"Are you alright over there dude?"
"I would be more alright if I were somewhere else," the werewolf retorted, hoping it would shut him up and mask his growing sexual frustration.
"Harsh much? Geez, I'm just studying, I can't be that horrible to be around."
Derek didn't say anything, just stared resolutely at the book in his lap. He heard Stiles sigh.
"Look, I know I'm not your favourite person, and you'd much rather be off doing wolf stuff, whatever that is, but I appreciate you looking after me." Stiles' tone of voice was surprisingly sincere and Derek couldn't help but turn to look at him, shocked by his honesty.
"You're not..." Derek started, suddenly terrified that Stiles might think he didn't like him. That wasn't it at all. He liked him too much. "I don't hate you," he finished.
Stiles gave a small smile that made Derek's heart leap in his chest and all he wanted to do was go across the room and sweep the boy up in a hug and hold on to him forever. It was a weird feeling for Derek Hale. He was not usually fond of hugging, just on principle.
"Thanks," Stiles said and Derek could hear the unsteady rhythm of both their hearts like drums in his ears. He didn't know what he was saying thank you for, or why his heartbeat had sped up, but it melted him from the inside. He felt his expression soften against his will.
"You're welcome." It was barely a whisper, but he knew Stiles had heard. The brunette was looking at him with an intensity he had never seen on him before, sitting in the edge of his chair like he was debating getting up. Derek didn't take his eyes off of him, unable to back down from whatever was happening between them despite his brain yelling at him to run away.
Stiles tapped his pen against his lips, clearly debating on something and Derek's eyes focused on it against his will. That pen -it was killing him.
And it was only because he was watching the movement of the pen that he saw the faintest of grins pass across the boy's lips, a quick quirk of his mouth that declared some sort of victory over what he was thinking about and made Derek have to bite his tongue to keep from licking his own lips.
And then Stiles was on his feet and moving toward him. Derek gripped the book in his hands, his fingers tightening around the pages and causing them to wrinkle. He didn't care and Stiles didn't yell at him for ruining a library book. Instead the brunette came to stand next to him, looking down at him with those big brown eyes and Derek found himself caught in them.
Stiles leaned down and pried the book from his hands and the brush of their fingertips set Derek's skin on fire. This was ridiculous, this could not be happening. This was not Derek Hale's life, it couldn't be. Whatever was happening it had to be a dream. He'd wake up any minute now.
But he didn't wake up and Stiles chucked the book on the floor, not taking his eyes off the werewolf, a smug expression on his face that was usually accompanied by a sarcastic remark that would make Derek want to hit him. But there was no sarcasm, no snark, just Stiles looking at him as his body grew hotter, his erection clearly and embarrassingly apparent.
He watched as Stiles' tongue darted out to lick his lips and Derek realized that the human was teasing him. Teasing.
A low growl escaped the werewolf's throat and he pulled Stiles down onto his lap with no resistance. And then he was kissing him, a hungry press of mouths, a heated battle of tongues battling for dominance. Blood pounded in Derek's ears and he almost lost it when he felt Stiles groan into him. He gripped the human tighter, pressing their chests together, breathing in his scent, unable to believe that this was real.
When they finally broke apart they were panting, drinking in air, and looking at each other with a mix of shock and desire.
"How long have you...?" Derek started but trailed off, unsure of what he was supposed to say.
"Too long," Stiles replied, leaning forward to lick at the werewolf's lips, nipping at his jaw line and the hollow under his ear. Derek moaned, tipping his head back and letting the brunette suck on the sensitive spot of flesh.
"Stiles," he breathed, his voice catching in his throat. The boy's only response was to hold on to him tighter and hum against his neck, sending shivers down Derek's spine.
"My dad won't be home for hours," he murmured, kissing along the werewolf's neck and wiggling his hips against him. Derek let out a gasp as he felt himself grow even harder.
"Don't you have to study?" he asked in a vain attempt to be responsible. That was why he was here after all and not Scott. Stiles had some kind of test... he couldn't remember.
Stiles laughed. "As if I have to study to pass the SATs. You are a bit dense aren't you?"
Derek let out a low growl but couldn't bring himself to be angry at him for being so sneaky, not when he was getting everything he wanted, had been dreaming about. So he picked up Stiles like he weighed nothing and tossed him onto the bed.
Stiles looked up at him with half lidded eyes, that devious grin back on his face as if he knew just how good he looked sprawled out across the blankets. And he did look good -downright delicious. Surely it had to be illegal to look that good.
Derek crawled onto the bed after him, desperate to tough him again, and pinned him down by the wrists, delighting in the excitement that was humming through the human's body. He was practically vibrating with it.
"You have no idea how jealous I have been of that stupid pen all night," he murmured, nipping at Stiles' neck and making the boy groan and buck his hips upward.
"Well now these lips are all yours," he replied, his voice breathy, and when Derek pulled away to look at him he was smiling and he found himself actually smiling back, a tentative gesture that transformed his entire face.
"Don't let me fuck this up," he said to Stiles, stroking his thumb across the boy's palm affectionately.
Stiles leaned up to kiss him, dragging his teeth against the werewolf's bottom lip. "The only thing you're going to be fucking is me."
And when Derek met his eyes he knew he was lost.