Author's Note: Because my friend kept spamming me with pictures of black kittens with blue eyes and saying they were the kitten version of Derek...Tiny mentions of Scott/Isaac. Like, blink and you'll miss it.

If anybody asked, Derek did care, thank you very much for asking.

It was just that caring was harder for him than it was for most people, because caring meant that he was emotionally invested in an outcome of something, and that was difficult for him to accept. So he tried to care very little. Lock his heart away so that no one could find it and nobody could hurt him.

It was a life philosophy that suited him quite well, everything considered. There were exceptions, and those exceptions went by the name of Stiles, but other than that, he was content with his life as it was.

Until that one day when something tiny and frail showed up on his doorstep out of nowhere, and turned things sideways.

He opened the door that morning, expecting it to be like any other morning in Beacon Hills, when all of a sudden, he noticed a tiny black furry lump shaking and resting against the doorpost. He leaned down and poked a finger at it, unsure of what this was or what it was doing at his house. The lump let out a tiny squeak and grabbed his finger between its two front paws.

Oh. It was a kitten. And he didn't know very much about kittens at all, but he did know that kittens needed to be fed like any other creature, and he could tell that it needed to get inside and warmed up. So he gently scooped his palm under it and cradled it in his hands as he carried it back inside.

What did cats eat, anyway? They ate meat, right? He wondered idly if any of the pack members had left behind a tuna salad sandwich the last time they were over, as he ransacked the refrigerator. Bingo. There were some chicken cutlets stored at the back, and a quick smell test indicated that they were still good. He poured some water into a bowl and sat back and watched it eat.

It would have to go, once he got it fed and warmed up. He wasn't a cat person, not at all, and he really didn't feel like a kitten around werewolves would be the best thing. So, really, it was all in the kitten's best interest. Not just some selfish thing of his own making. Really. He would insist to that fact, even if put on the stand on trial.

It was at that very moment of decision-making that Stiles burst in through the back door. "Hey, Derek," Stiles said. "Whatcha – oh my God, you got a kitten."

"No, I -" Derek started to protest, but Stiles was already cradling the kitten in his arms like he had lived with a cat every day of his life. He could hear the thing purring from across the room, loud and clear. Of course the cat would like Stiles. Of course it would.

The cat's eyes blinked open and stared contentedly up at Stiles. It batted a paw tentatively at his chin. "Who's a good boy? Or girl, I can't tell," Stiles said, scratching his index finger under the cat's chin. "You're so cute." He looked up at Derek. "How did you manage to find a cat that looks like your soul?"

"My what?"

"Your soul. Because, you know, your soul is black, and so is this adorable little kitty cat's fur, and yes, yes, you are my good little kitty," Stiles said, his voice rising in pitch as he held onto the cat. "It's so fitting. And its eyes are even blue. Like yours. So it's like I have Derek, and mini-Derek. Derek's shadow. Shadow. That's a perfect name for you." He glanced down, focused on trying to figure out something. "Okay, it's a boy. Definitely a boy."

"Because you really expected my soul to be a girl cat," Derek said, taking a sip of water and setting the glass down on the table. "Stiles, put down the cat."

"No." Stiles stood defiantly with Shadow and cradled him closer. Shadow closed his eyes and batted a paw over his face as he drifted off to sleep.

"I'm not keeping the cat. I was letting it warm up and eat a little breakfast, and then I was going to find a nice place to let him roam wild. Like cats should."

Stiles was aghast. "No. Shadow is staying right where he is." He stepped closer to Derek, and whispered in a harsh, brisk whisper, "And if you let him stay right where he is, I'll let you have my ass whenever you want it."

"Whenever I want it?" Derek asked, a quixotic expression streaming across his face. They'd been together for a while now, and things were good between them – really good, by Derek's standards, even – but was Stiles serious when he proposed this? "Are you seriously offering me sexual favors to keep a kitten?"

"No, I'm saying that if you keep the kitten for a month, that you get to have me, whenever you want to have me."

"So if I'm hard and horny and lonely, except for that thing scampering around -"

"You won't be for long, is what I'm saying."

Derek looked Stiles up and down, taking in all of him – it was almost an appraisal of some sort. Maybe it wouldn't be the worst thing to keep this kitten. He had never been particularly a cat person, by any stretch of the concept, but maybe, he could learn to live with it. For a month. And then it could go back out into the world and roam free, and he would have done his service to Stiles, and he could tick the box off on "have you ever done a charitable thing for a tiny, defenseless creature?" "Deal."

Stiles reached up and planted a kiss on his lips. "Thank you, Derek," he said, and then he sashayed his hips – almost infuriatingly, as if he was trying to torment him into taking advantage of the deal not even an hour out. "Shadow and I appreciate the gesture."

"Yeah, don't mention it." If Stiles continued speaking for the cat like that, however, all bets would be off.

Derek sat on the couch a week or so later, staring at his phone, almost as if he was willing it to ring. He felt a little pounce on his shoulder. Looking over, he saw that Shadow had jumped onto his shoulder, and was curling into his neck. Damn cat had already learned how to take after Stiles, and it had only been a few days. Was he sure that it wasn't his shadow instead?

He picked up his phone. A deal was a deal, and he knew that Stiles probably was over at Scott's, probably playing video games – or whatever it was that the two of them did. Talk about their boyfriends, Isaac and Derek? He puffed out his chest at that thought, and hoped that he would be compared favorably, if that was the case. Not that self-confidence was something that he abounded in, but he knew how Stiles saw him – saw their relationship, as a whole, even – and thought that the odds that Stiles would brag about him were higher than they were not.

He called Stiles, and listened to the phone ring on the other end – one ring, two rings – and Stiles picked up. "Yo, this is Stiles," he said. "What's up?"

"A deal's a deal," Derek said, intoning his voice very seriously, trying to communicate how grave the situation was with just four words. "So, if you and your 'yo' want to get over here..."

"I'm on my way," he said, and Derek heard something crash in the background. He winced at the sharp sound, and cast the phone away from his ear. "Oops, I dropped the game controller. Crap. I think I broke something. I'll be there shortly. Just wait."

Derek clicked off from the phone call and looked over at Shadow. "He's crazy, isn't he?" Derek said. "And I'm the one talking to a cat, and half-expecting an answer, so I guess I'm one to talk."

Shadow just threw his head back and meowed in reply, showing off his tiny little kitten teeth as he did so.

"Right. Okay."

He meowed again and walked across Derek's shoulder, leaving tiny little claw impressions along the way, digging into his skin. He turned and butted his head against Derek's shoulder – once, twice. The fur on top of his head was super-soft, not like a werewolf's fur, which was more coarse and patchy than the soft silkiness that he felt against his skin. He could appreciate the difference, even if it was one he wouldn't have ever thought of before.

Maybe it was kind of cute after all.

Last time he had thought that, he had gotten a smooth-talking, rambling boyfriend out of the deal.

Maybe that wouldn't be such a bad deal to make the second time around. Just this time, it was in a smaller, more compact form that meowed, liked to shower him with affection even when he wasn't sure about it, and ate chicken like it was never going to see food again.

Besides the meowing thing, that didn't sound too different than Stiles, anyway.

Stiles stumbled through the door exactly sixteen minutes later – not that Derek was keeping track. Much. "Sorry, it's just that Scott and I were having a Super Smash Brothers marathon, and I told him you might be calling, and he was totally cool with that because Isaac might be calling him too – I wouldn't be surprised if he was calling Isaac right now because I left, anyway, and I dropped the game controller when you called, and -"

Derek sealed his lips over Stiles's, as if to silence the stream of babble that was coming forth. He pulled Stiles close, and ran his hands all over Stiles's back, drawing him closer to him with every motion of his hands. "Don't worry about it," Derek said. "You're here. That's what I care about."

"And how's my little Shadow?" Stiles said, scooping Shadow up into his arms and nuzzling his nose against the soft fur. "Giving Derek a hard time for me when I'm not here, I hope."

"That cat takes more after you than it does me. I don't think he's my shadow," Derek said. "He's all mini-Stiles."

"Dude, if I was a cat, then we would be fighting like cats and dogs, and the sex wouldn't be near as fantastic, and why did you call me over here anyway? Because if it's not for sex -"

"You were the one who outlined the terms of the deal of me keeping this cat."

"That I did, yeah – oh." The realization of what Derek meant washed over Stiles, and he puckered his lips into a finely-tuned pout. "It is for sex."

"What did you think it was about?" Derek's eyes flashed indignantly.

"I wasn't sure if you had bought a new backgammon board and wanted to break it in with me," Stiles said, biting back the impish smile that hid at the corner of his lips. "Or, you know, you could have -"

Derek's lips were on his in an instant, taking away the ability for him to speak, or form coherent sentences, or any of that. "Stop talking," Derek said, whispering against his lips. He grabbed at the fabric of Stiles's shirt, and Shadow squirmed out of Stiles's grasp and jumped onto the floor, as Derek cast off the shirt. Shadow peeked up from the tent of fabric that formed around him, blue eyes staring unblinking out from the void.

"Okay." Stiles said, and he backed up, feeling Derek's arm resting against his back, preventing him from moving too far back. He looked at Derek, and Derek's eyes were clouded over with – he peered, trying to decipher the emotions that bubbled under the surface. No one could ever proclaim him to be the most perceptive person in Beacon Hills, but he thought that he was beginning to figure out some of the outermost layers of what made Derek tick. But it appeared to be lust, this time. Lust mixed with something else that added to the piquancy of the lust.

Derek dipped his lips to graze at the edge of Stiles's collarbone, running sloppy kisses in a scatter on the bone, and Stiles threw his neck back in a near-perfect arch. Derek's hands ran along the sides of his torso, clasping his body in his own grasp. He took Stiles in his hands and dipped him low to the bed, brushing the back of his spine against the sheets in calculated swishing movements – back and forth, back and forth, until finally, he laid him down in a crown of pillows.

Derek slid back over him, removing his shirt as he did so, and looked at him, and it took Stiles a moment to recognize the look. It wasn't really one he had ever seen on Derek before, but it almost perfectly mimicked Shadow's facial expressions, complete with the tiny little imperceptible head tilt. He hummed something under his breath and languidly stretched out over top of Stiles, brushing the tips of his fingers against Stiles's hand. "One word about the cat, and this all ends here," Derek said.

"Was – wasn't going to say anything," Stiles said, sucking in a deep breath at what was before him. It felt like Derek covered every inch of him, blanketing him in his warmth. He tilted his head upward and brushed his lips against Derek's jaw, and Derek moved his jaw into Stiles's touch, as if to silently beg for more.

They stayed like that, Derek practically pinning Stiles to the bed – for a few moments, until Stiles felt something digging into his thigh. Derek could feel it too, for he rolled off of Stiles, almost reluctantly, and pulled down his pants.

Stiles hitched himself up on the pillow and found that his legs spread of their own volition, which was helpful when Derek climbed back in-between them. A small bottle of lube was clenched in one hand. Before Derek popped the lid on the lube, he unfastened Stiles's pants, and Stiles helped to shrug them down his legs. He didn't need them, not when Derek was sitting there naked and wanting him.

Derek liberally coated three fingers of his right hand in lube, and he moved closer to Stiles. He sealed his lips over Stiles's, exuding warmth, as he jacked the fingers inside Stiles's hole. After a time, yes, they didn't have to do as much prep – and sometimes he liked to do it himself, so to speak – but there was something about being able to see the look in Stiles's eyes when he did it, that was like nothing else.

He cared about Stiles. That much was a foregone conclusion, a goddamn certainty in his life where there had never been much certainty. And sometimes, he found really strange ways to show his – well, normal people would probably term it as "affection," but for him laid closer to "lack of disdain."

He carefully slid inside Stiles, lube gliding and easing the pace just right – he knew what Stiles had told him in the past, and his body signals were doing the work for him. This was "yes, yes, please, God, Derek, yes" - which was totally an area that he could help with. He continued to engulf himself further in Stiles's touch, and buried his face in his neck. A few nips here and there would help to hide the emotions that he felt, and then everyone would know that Stiles was his. Not that there were any questions about that, he hoped.

He felt something feather-light on the bed behind him, but he didn't want to tear his eyes away from Stiles for a second. Maybe it was just a hallucination – and then Stiles, who had been silent except for ragged gasps of breath every time Derek's balls slammed against his skin, said with a laugh, "oh my God, Shadow, that tickles!"

He looked behind him, for just a second, and saw that Shadow's tail was rubbing against Stiles's foot. So he took his fingers and found that ticklish spot right under Stiles's rib cage – the one that he had found out about purely by accident, but used to his advantage whenever possible. He ran his fingers over the spot, and Stiles continued to laugh. "Are you two conspiring against me?" he asked, between shudders of laughter.

"No," Derek stated simply, and kissed the side of his neck, balls slamming into him again. Stiles jerked his foot up this time, and Shadow went scattering off the bed, looking for a more secure place to sleep – or wait until the rocking stopped.

Shadow's escape must have foretold Derek's own orgasm, as he came with a grunt – maybe the cat didn't want to be a direct witness to this. Did cats get scarred by viewing sex? That would be something to investigate at a later time – but his thoughts were overpowered by the feeling of Stiles beneath him, writhing in his own pleasure.

So this is what caring about someone was like, he thought, as he cradled Stiles's chin in his hand and kissed him again, riding off the post-orgasmic high with a taste of Stiles crashing beneath him.

Dare he say it, it felt good.

Stiles woke up one morning, tangled in a happy pile of Derek's limbs – and nothing else. Derek's calves rubbed against his thighs, a foot hooked around back of him, pulling him close even in his sleep. He heard a faint rumbling from somewhere nearby – it didn't sound like a stomach, but – he peeked one eye open, and saw Shadow staring back at him from his perch on Derek's side. Shadow's gaze met his full-on, and the cat didn't blink. It was kind of unnerving, in a way, but also really, really adorable. "Hi there," he whispered, crooking his finger under the cat's chin and scratching there. The rumbling – purring, he amended – deepened at his movements.

It had been almost a month since he had come over that morning and saw a tiny kitten in Derek's kitchen. Almost a month of constant, unending, passionate sex – on Derek's terms, but really, on his, because without him, there would never have been anything to start.

It was fantastic. Maybe he could convince him to take it beyond a month. Keep the kitten, keep the sex. He could never be satiated.

Derek stirred and looked up. "Oh," he said, looking at the cat, and then at Stiles. His eyes darted back and forth between the two, and his eyes dilated. "You're awake."

Stiles yawned and nuzzled at the back of Derek's neck. "Yeah," he said, "and Shadow and I have been playing the staring game. He's winning."

"And here I thought you were the defending world champion," Derek said. "Considering you can't take your eyes off me when I'm on top of you."

"He's knocked me off my throne," Stiles said, almost in a mournful tone. They laid there for a few moments, taking in each other's breathing and heartbeats, and feeling Shadow against Derek's skin. And then Stiles broke the silence. "Are you going to keep him? Because if you're not, I can ask my father if he wants a kitten, but I think he might be allergic, and -"

"Don't worry about it," Derek said, cutting him off. "It's taken care of."

"Taken care of? You don't mean -"

"You'll see what I mean." Derek planted a kiss on Stiles's lips and looked at him. "Don't look at me like that. The cat's going to be just fine."

"Okay." Stiles couldn't help but feel a little dubious at that remark, but he let it slide. For now.

A little while later, they got up, and Stiles caught a glance at Shadow's food and water bowls out of the corner of his eye for the first time in a while. It wasn't just two mismatched bowls from Derek's cupboards anymore. It was black – how fitting, really – with white letters spelling out SHADOW in a bold font. Inside, he could see scraps of chicken. Next to it was a smaller, matching bowl, filled almost to the brim with water.

He couldn't help but smile at the sight.

"You're keeping him," he said, walking up behind Derek and embracing him. He planted a kiss to the side of his neck. "I saw the bowls. Very cute, by the way."

"The guy at the pet store said they were good bowls," Derek said. "And I wanted everyone to know that they were his, so that no one tries to eat his food if there's nothing in the fridge."

"You care," Stiles said with a laugh. "Oh my God, you actually care about this cat. I'm so not used to hearing you say things like that."

He could practically feel the heat of Derek's glare in response. "Because I don't usually care, okay? You know that. But I make exceptions. First for you, now for this cat, and I don't plan to make anymore any time soon. Unless -"

"Unless what?"

"Unless one day, you and I have kids of our own."

The words hung suspended in the air, and Stiles hummed in a breath of air as he pressed his lips to Derek's neck and worked his tongue over the veins. "I would hope so," was his only reply. "One day."

Shadow leaped up on the counter and nuzzled against Derek's hand. At Derek turning over his hand to him, he climbed into it and promptly fell asleep, and Stiles closed his eyes where he was standing, and Derek couldn't help but smile at the feeling. What a tableau the three of them made.