disclaimer: I don't own the rights to Life with Derek, I'm merely borrowing the characters for my own amusement.

There was a stranger standing in his kitchen.

Derek paused in the doorway, dropping the hand that had been rubbing the sleep from his eye.

A stranger who appeared to be in the middle of polishing off the last of Derek's cereal by the looks of it.

Suddenly Derek felt much more awake than he had two seconds ago.

"Dude, don't take this the wrong way," he said, taking a step forward and folding his arms, "but who the hell are you?"

The dude in question looked only momentarily surprised by the interruption, then, for reasons Derek couldn't begin to fathom, given the situation, relaxed back into the counter he'd been leaning against. And smiled.

"Oh hey. You must be Derek. I'm Sean, from over in 3E." He gestured with his hand holding the spoon vaguely, to the apartments above.

"Get lost this morning?" Derek said watching as Sean proceeded to use the spoon to scoop up another mouthful of cereal. "Or did you just run out of your own food?"

Sean laughed.

"Actually, I'm waiting for Casey. She said I could help myself to whatever on the way out."

"Did she?" Derek smiled too now. But it was all teeth. "Excuse me a minute, will you, Shane?"

Not waiting for a reply, Derek turned back down the hallway he'd just stumbled from, and went to the closed door of the bedroom next to his own, and knocked. Loudly.

"Just a minute!" came the muffled reply.

"Why is there a strange guy standing in my kitchen eating my cereal?" Derek demanded.

"It's our kitchen."

It wasn't actually, but he'd save that argument for a later time. There were other, more pressing, things to discuss right now.

"Why is there a strange guy standing in our kitchen eating my cereal?"

"Because I told Sean he could grab breakfast on the way out."

There it was again: On the way out.

"You know, I hear talking," Derek growled, "but I still don't hear why there is a strange guy eating my cereal in our kitchen."

"Oh my god, Derek." The door finally swung open. "I will buy you a brand new box of cereal, ok?"

Casey scowled up at him from underneath the pink towel wrapped around her head. It matched the fuzzy pink bathrobe she had tied at the waist and the slippers on her feet.

"I think Shane should buy it."

Casey's scowl deepened with exasperation.

"It's Sean," she corrected. "And you can't ask him to do that," she added with all the primness of Ms. Manners imparting her wisdom, "He's a guest."

Derek laughed without humor.

"He's not my guest."

Casey's eyes narrowed.

"Remember your little friend from Thursday?" she cooed coolly, "She certainly wasn't mine, but you never saw me throwing a hissy fit over her taking one of my almond milk yogurts that morning, did you, Derek?"

"That's different," said Derek stiffly.

"Oh, really," Casey said, arching an eyebrow.

"Yeah," said Derek, "Because I don't give fuck about your stupid girly yogurt right now, Casey. You still haven't answered my question: what is he doing here?"

She gave him a funny look before answering.

"I think it's rather obvious, don't you?"

"I meant," Derek scowled, "in my apartment."

"Our apartment."

"This is my apartment, Casey. Mine! Not ours. You're just staying here until you find your 'suitable arrangements' or whatever, remember? That was the deal. If anyone's a 'guest' here, it's you, and you shouldn't be bringing your own 'guests' around. That was not part of the deal."

She didn't even have the decency to blink at his outburst.

"First of all, Derek, I'm your temporary roommate, not a guest. Secondly, I have just as much a right as you to bring whoever I want here because it is our apartment, for now at least. And thirdly," she squared her shoulders, "you're right. This wasn't part of our deal. But," she went on before he could claim any victory, "it also wasn't part of our deal that I live like a nun either. We all have needs, Derek, not just you."

"Unless you want me to heave on you," he suggested, "let's make a deal you never say those words again."

"What? Needs?" she taunted.

"Casey," he growled.

"Derek," she smirked.

He grit his teeth.

"Get that guy out of my kitchen. Before I do."

"He'll be leaving soon enough," she assured. "Once he finishes that bowl of cereal, of course."

And with that, she pushed past him and flounced to the kitchen.

xxx

Despite her winning exit, Casey felt more like breathing fire than doing a victory dance as she set about pulling things out of the fridge to make a breakfast smoothie.

"Everything ok?" Sean asked. She didn't imagine he sounded a little weary as she slammed the box of spinach on the counter. No doubt, he'd heard the exchange in the hallway. This was a small apartment and they hadn't exactly been whispering.

"Yeah," she lied, flashing him an unconvincing smile. "Sorry about all that. Derek and I aren't … the best company to have around together," she grimaced apologetically.

"No worries, no worries," Sean said, easily resuming to his genial nature. Sliding up behind Casey as she fiddled with the blender, he wrapped his hands around her hips. "So..."

The low, suggestive tone he'd suddenly adopted signaled he was about to bring up something about last night. At any other time, she might've liked to hear it, but she wasn't especially in the mood for it right now while she still had Derek on the brain.

Before Sean could say whatever it was he was going to though, and before Casey could interrupt him, the devil himself reappeared in the kitchen.

Any notions Casey had seconds ago of telling Sean he should probably leave, died on her tongue as Derek glowered at them. Instead, she met his gaze unwavering, daring him to say something.

His jaw tightened but he said nothing.

Sean, however, took the opportunity to.

"Uh, look, man, I'm, er, sorry about the cereal," he apologized sheepishly. "Didn't realize it was, um, special, or yours, or whatever. I'll totally buy you a new one," he offered.

Derek just looked at him.

"Don't worry about him, Sean," Casey supplied, "Derek just gets grumpy when it comes to sharing. He's like a two-year-old that way. And in many other ways," she smirked.

"You know I don't share Case."

Normally, she would've rolled her eyes at such a classic Derek response. She'd heard him say it a thousand times before.

There was something odd about the way he said it this time though. And an edge in the look he gave her.

Sean, however, didn't seem to grasp the slippery slope he was on though, because he said, laughing, "Well, he does seem pretty grumpy. Maybe he just didn't get enough sleep last night." Speaking into Casey's ear, he added, "I know I didn't. Not that I'm complaining…"

Evidently, he didn't say it low enough though, or maybe Derek just got the gist anyhow because he said, as Casey flushed, "You do realize Casey is my step-sister right?"

Sean frowned.

"Yeah…." he trailed off, suddenly looking weary again, "You're not, like, wanting to beat me up or something are you? For fooling around with your sister?"

"Stepsister," Casey corrected automatically.

"No, Shane," said Derek, "I'm just gonna show you the door."

"Derek-"

"No, no, it's ok," said Sean hastily, as Derek advanced, "I should be heading out anyways. I, uh, got stuff to do today, so...Thanks, Casey. I uh, had fun. Maybe we could hang out again, sometime? At my place?" he added with a glance at Derek, as he was all but forced backwards, out of the kitchen and into the hallway while Casey followed.

"Out," said Derek, reaching around to the front door and throwing it open. "Now."

"Text me!" Sean called as it slammed closed in his hopeful face.

There was a moment of silence before Derek rounded on Casey.

"Well, I think you've got a real winner there, Case. Seems like a real genius."

"I didn't choose him for his brains, Derek," was her lofty reply.

"Just went out into the hall and grabbed the first guy you found, eh?"

"Something like that," she sniffed.

"I bet you didn't even - with that guy. You're just pretending you did," he accused, somewhat wildly.

"Why would I do that?" she frowned, truly stumped by the ludicrous notion.

"Payback," he said, "For Thursday."

Casey snorted a laugh.

"I don't care about your girl from Thursday, Derek."

"Why'd you bring her up then?" he demanded.

"Me? You were the one who just -"

"Earlier! When you were talking about yogurt."

"I was making a point-"

"Exactly!"

Casey stared at the finger directed at her chest. Then looked at Derek.

"You're crazy."

"So you don't deny it?" he said victoriously.

"That you're crazy?" she blinked.

"That this is all about making a point about Thursday!"

"And what point would that be?!" she demanded, placing her hands on her hips.

"That you - that I - that Caroline -"

"You know what I think, Derek, I think it's a little late to get all brotherly on me now. Not to mention really weird."

"Brotherly?!" he choked.

"Yeah," nodded Casey, completely serious and more than a little impatient, "You're acting like an overprotective older brother who can't handle the fact that their little sister is sexually active. But you're not my brother, Derek, and you're not older me than. I'm four months older than you, remember?"

She wasn't sure when it happened.

Only that one minute Derek was standing by the door gaping at her, and the next he was right in front of her, wrapping an arm around her waist, hauling her against him and crashing his mouth down to hers.

Her squeak of surprise got lost against his mouth as he kissed her.

If that was what you could call it.

She wasn't sure that you could.

She'd been kissed before, after all, and this was nothing like any of those.

He sipped at her top lip and sucked at her bottom one. He nipped at her mouth, then soothed the bite with his tongue, before sliding it deftly in to meet her own.

His arm was like a band around her body, tethering her to him, pressing them so close, she could feel the heat of his body thru the terry of her robe. She wasn't even aware that the towel on her head was slowly slipping off until it dropped suddenly with a gentle plop into a puddle on the floor. Derek wasted no time. He slide a hand up, into the damp hair at the nape of her neck and tugged, with just the right amount of pull that Casey moaned, angling her neck back more, deepening the kiss further until just quickly as it started, it stopped.

She was still so caught up in the feel of his lips and the taste of his tongue, she swayed forward, blindly seeking at first. Then she felt his arms drop away as he stepped back, and her eyes fluttered open.

"I know I'm not your fucking brother, Casey," Derek rasped. "And it's only three and a half months," he added, as he turned and walked away.

She watched him retreat down the hall and stared as he disappeared into his room and closed the door behind him with a snap.

- GoddessoftheMaan

Just something that's been rattling around in my head for a while. Hope you enjoyed.