A/N: I was cleaning out my files when I chanced upon this little fic. I wrote this years ago before I graduated college and I think I had big plans for it at the time, but when I re-read it a few nights ago I figured that it could stand up on its own.

Updates will be done weekly, reviews are definitely welcome and of course, Life With Derek's not mine.

Enjoy.

Derek and Casey: 1/3

Derek Venturi was a person easily amused by the silliest things. He could be stuck alone at the mall and be there for hours, just watching people – how they moved, how they walked, how they talked – and he'd be content.

A couple of years back he had been particularly amused by his father when he had first gotten around to dating Nora. To say that his father acted goofily was an understatement; his father had been flat out ridiculous, and he didn't even care. He had been that much in love. It had been refreshing to see him break out into dance moves while doing house chores and breaking into random songs while he cooked that Derek and his siblings didn't have the heart to mock him for it.

And his father had acted especially silly right around the time before the wedding. He had suffered through some pretty weird mood swings right after he proposed – extremely giddy one night and highly agitated the next. But, once again, the Venturi kids took no offense to whatever things their father had said to them, chalking up his weird behavior to frazzled nerves.

When the McDonalds moved in, the amusement level in Derek's life rose exponentially. Except for the cramped space in his home, Derek really didn't mind them moving in. All in all they had brought more life into their house than anyone could actually say. He had always wanted a younger sibling to play sports with (no offense to Ed, but he just didn't cut it when it comes to hockey), which he found in the form of Lizzie. Nora did a very good job of playing mom to all of them. And even if she didn't, he probably still wouldn't complain, considering how happy she's made his dad.

Then there was Casey. Derek just had to smile at the thought. Casey was like this huge experiment that he just had to try out. Although he did have a sister in Marti's form, he never had a sister of his own age. At first his mind couldn't wrap around the concept of living with a girl that was his own age. Wasn't that like instantly having a twin sister?

Very quickly he realized that he and Casey were nothing alike, and there would be no chance in hell that anyone could ever mistake them for siblings, much less twins. She had been weird and he just couldn't resist prodding her. Yes, Derek Venturi was now mature enough to admit that he had thoroughly enjoyed annoying the hell out of Casey McDonalds. Just as long as she didn't have to hear it of course, else he'd probably get a mouthful.

What was great about Casey was that whenever Derek pushed her buttons, she would push right back. She didn't always know how to push back, but at least now she knows how to retaliate instead of letting everyone walk all over her. He would like to think that he had something to do with the growth of that backbone of hers. She certainly didn't have one before they moved in.

But over the course of the years, their outright banter battles had died down to a simmer, practically civil conversations as compared to what Edwin and Lizzie were going through. He still couldn't believe it when his father had called their younger siblings almost as bad as he and Casey has been a couple of years ago. Surely, they weren't this noisy or this annoying back then. But then again maybe it's just the way it was. Maybe puberty shouldn't happen in such cramped spaces.

And really, he was one to talk, being in his particular state and all.

After almost three years of living together, he and Casey had settled into a somewhat peaceful existence. Sure, they still bantered and sparred verbally, but he thought that it was only for formality's sake. The bantering was a comfortable, familiar place and both parties knew the terrain. People expected them to banter, so they did.

What people probably didn't expect was him watching her at the dinner table or while they were all watching television in their living room more often than he would like to care to admit. He had also grown a certain fondness of making her smile, which, from whatever angle he looked at it, was a bad thing.

He didn't want to be all Flowers in the Attic with Casey; it's just wrong. Then again, he figured, if a whole series of books had been written about the repercussions of having children grow up in limited spaces, and then maybe there is something behind his situation. After all, he and Casey didn't exactly grow up together and they weren't really related. She was a great girl, he was a great guy. They were just two great people thrown into this mix and how the hell could their parents not have seen this coming?

Still, he had decided that it was indeed wrong and extremely selfish of him to go after Casey. Besides, it would've probably only freak her out, not to mention possibly ruin their family. So, he resolved to keep it in his pants and go on with his life.

The plan was going great, extremely great. Up until a month ago, that is.

A month ago their Christmas break officially started and school was out. As with all mini-vacations, the first few days of those were spent with the kids sleeping. But that particular Thursday morning, for some unknown reason, he woke up extremely early. He groggily went down the stairs, taking in the lack of light in his vicinity. God, how long ago was it since he last woke up before the sun was up? He padded his way to the kitchen, totally not surprised at the fact that nobody was up yet.

"Derek, you're up early," somebody greeted, making him jump. Bleary eyed, he realized that it was indeed his stepsister who greeted him, and, unlike him, she was already physically composed even though she was still in her pajamas.

"Yeah, well," he said, stifling a yawn and opening up the fridge to get a glass of milk.

He didn't finish that sentence but he did sit down opposite her on the dining table. He couldn't really call the silence as awkward, but since it just hung in the air like that, it wasn't totally comfortable either.

He wanted to open his mouth to start up a conversation but since that funny feeling that he gets whenever she's around is already fluttering around his stomach, he decided to forgo it. That pesk of a feeling had been known to go into overdrive whenever they were alone in a room together, so it was probably for the best not to risk it.

So he contented himself at watching her under the guise of playing with his glass of milk. She was staring out the window, where the sky was still a dusky purple-tinged color. It was a good deal lighter than it had been a few minutes ago, but still nowhere the shade he would consider as real daylight.

He had his glass up to his lips when suddenly she turned towards him, a weird look on her face. He almost dropped his glass, his mind going in all directions, thinking that he had been caught, when he realized that she was grinning.

"What?" he asked.

"Snow!" she squeaked. "It's snowing!" And without so much as a warning, she bolted out of her chair and headed for the front door.

Shaking his head, he followed her out of the kitchen and was actually surprised to see that her pink fluffy coat was still on the coat rack. He grabbed his leather jacket along with her pink one and followed her onto their lawn, which now looked as if someone had sprinkled confectioner's sugar over it.

"Hey!" he called, putting on his jacket. She was in the middle of the lawn, looking straight up at the powdered snowflakes that fell. That Casey would still be this excited over snow in Canada was beyond him. "You're going to catch a cold with what you're doing!" As he didn't really have the chance to put on decent shoes, he crossed their lawn in his thong slippers, scanning their surroundings. It was of no surprise that nobody in their street was up. Porch lights were still on, bedroom lights were still off, which clearly meant that the whole of his street was still fast asleep.

So why was he out here freezing his toes off again?

A soft laugh emitted from Casey's lips, drawing his attention towards her once more. He saw her wipe at something on her face, probably a snowflake that landed on her nose or something. It had been a long time since he had seen her this free; then and there she looked very much like Marti when she gets a present of some sort.

She was a few feet away from him, mid-laugh when she turned around to his face him. There was such mirth in those eyes that he couldn't believe that it, all of it, came from something as mundane as snow.

And that's the moment he caved. He had never been one for reining in one's emotions, for controlling impulses; it was a wonder he held out for as long as he did. (After all, what Derek wanted, Derek got.)

He crossed the distance between in them in five freezing strides, his eyes trained on her form all the way. She was still smiling up at him, that giddy, childlike goofy smile even though they were only a couple of inches apart – closer than they've ever been without fighting or wrestling over something.

He gave in to the temptation and let his lips form a soft smile. Still, he looked directly into her eyes, not shying away as he had done for the past few weeks, and willing her to see. Gently, he straightened out her fluffy mass of a jacket and settled it over her shoulders, his hand not leaving their spots as they clutched at the white fur lining on her chest. Her smile wavered then, as if she realized just how close they really were standing to each other. Her brows furrowed at him but still she didn't do or say anything.

"Casey," he started, his breath misting over the space between them. "I want you." Okay, there. He blurted it out. It's not like he had a well-formed speech inside his head anyway so that probably was the best it could've gone.

Her eyes widened at his words, her gaze fleeting at every other direction but his, as if waiting for somebody to jump at them. Still, she didn't take a step back or shrug off his hands though, which Derek took as a good sign.

His eyes flitted over her lips, her very full lips, which he sincerely wanted to feel against his own that particular moment. But then, he thought, knowing Casey, she'd probably slap him for it and run back inside the house screaming her head off. Finally she noticed where his gaze rested and, consciously or otherwise, ran that pink tongue of hers over those luscious lips, grazing ever so gently that he wanted to groan.

He leaned in and was pleasantly startled at the fact that she still has yet to move away. With shoes on, they were almost of the same height, but their thong slippers made him a good deal taller than she was, so much so that he was towering over her form. He could feel her tense up underneath that mass of a coat, that unconscious act bringing him back to his senses. Instead of making contact with her lips as he had fully intended, he settled for planting a soft kiss on her temple and moving away.

He stepped back to watch her reaction, which, ironically enough, was just as amusing to him as any other acts of hers. Her face morphed from a look of stunned surprise and when she finally looked at him, she opened her mouth to say something to him, but looked like she thought the better of it. She closed her mouth, stared at him for a few seconds and finally shook her head. And then she went off to do what he had hoped she wouldn't – she bolted back into the house at speeds he didn't particularly know she possessed, leaving him in the middle of their porch with snow dusting his body.

Well, he thought, at least the screaming bit was left out.

After that incident Casey had locked herself inside her room for the whole morning, giving their parents a nice little surprise to see their eldest son as the first one up that specific morning. From then on Derek hadn't gotten her to say anything to him or even look at him for that matter. He baited and baited and baited, but still she wouldn't budge, and just flat out ignored him. The sheer amount of will power she was showing kind of surprised him actually. If she had been this determined to ignore him back then, he probably would've missed half of his life's worth of amusement, since he probably would've backed down after a few weeks of this kind of snubbing.

He had, however, managed to get her to break a couple of glasses, a total number of three porcelain plates, and the hallway vase, which, fortunately for her, was of no particular value to anyone. She was so jumpy around him that every time he entered the same room she was in, she was very likely to break something.

After a few days of this weird situation, their parents had been concerned enough to intervene. His father and Nora had sat him down last week to ask him to apologize to Casey, for whatever it was he did, saying that it didn't matter who had done what first, it was just best to get it over and done with. This cold shoulder he was receiving wasn't worth anything, Nora had said. And they really couldn't afford to lose any more dishes, his father had added conspiratorially before leaving his room.

Now he was seriously considering taking his father's advice and just apologizing for the whole thing, even if he did mean it, all of it. Obviously she didn't believe him anyway and this way he could still get out of the semi-mess he had placed himself in scott-free.

He was just about to talk to her this particular lunch period, actually, and had already started scanning the lunchroom for any signs of her. So determined was she to avoid him that she took all measures to not see him anywhere in school ever since it resumed a couple of weeks ago. Obviously she wasn't going to let this go easily, which made it harder for him to make any kind of apology seem sincere.

Just imagine his surprise to see her right there, seated at his table, waiting for him, lunch tray filled with her usual apple and peanut butter and jelly sandwich. Warily, he scanned the chair opposite hers; he wasn't particularly sure if they'd passed the whole booby trap stage just yet. Deeming it safe, he proceeded to sit down in front of her, placing his tray of juice and chili fries on the table.

He stared at her for a few seconds and she stared right back. Okay, maybe this was the perfect time to dish out the apologies. He was just about to open his mouth when she beat him to it.

"Are you messing with me?" she asked, her eyes full of seriousness.

The question caught him off guard and he just sat there, staring at her as if she'd grown a pair of horns on her head. "What?"

"I said," she began, enunciating every word clearly. "Are you messing with me?"

Quickly he scanned his head for anything he could have possibly done that constitutes as 'messing' with her. Snakes, traps, money? No, as far as he knew, he hadn't done anything lately.

"No," he said.

"Then what is your deal telling me," Casey started, but appeared to have had some kind of difficulty finishing her sentence. "That?"

He furrowed his eyebrows at his stepsister and discreetly scanned their surroundings. Okay, she wasn't making any sense. Was this some kind of trick? "What are you talking about?"

Her coloring reddened in an instant, as if someone had thrown her into a boiling pot of water. She shifted in her seat, a telltale sign that she was uncomfortable. "Christmas break," she began in a harsh whisper, looking around to check if anybody was listening. "That thing that you said to me that morning,"

Derek's eyes widened in understanding. "Oh," he let out. So she thought that he hadn't meant it. She thought that it was just one of his jokes designed to mess with her head. "About that,"

"Did you mean it?" she asked, cutting him off.

His head tilted a bit to his right at her question. Here she was, offering him a perfect escape route. He could just say one simple 'no, I didn't mean it,' and it'd all be over with. Sure, there was the chance of her being significantly furious at him, but that part he could handle. He was well used to dealing with a furious Casey.

He had decided. That was the way to go. Lying had always provided him good lee ways in his life and whoever had coined the expression that honesty was the best policy was nuts.

"Yes," he said, with as much confidence he could muster.

Wait, what?

Her eyes grew wide, obviously not expecting this answer. Well, he knew how she felt; he wasn't expecting this answer either. "What?" she asked, echoing his thoughts.

So there it was, out in the open. He could try lying again, but he figured that for some weird cosmic reason, this was the right path to plough through. "Yes," he repeated.

"Derek," Casey started, edging forward in her seat and bearing her weight on her arms resting on the table. "I'm warning you, if you think that this is a jo—"

"It's not a joke Casey," he said, interrupting her mid-rant. "I totally meant it. I want you, okay?"

If he thought that she had been red before, she was basically carmine right now. Again, she glanced at the people beside them, apparently waiting for them to do something. Derek looked at them too and only found a bunch of senior high school students who were too into their own affairs to care about what was happening at other people's tables.

She did that thing where she opened her mouth and closed it a couple of times and Derek had to fight the urge to let out a chuckle. Yeah, he figured, laughing in her face right now probably wouldn't be the wisest of ideas. He snaked his hand across the table to grasp hers. When she realized what he'd done, she violently pulled back both of her hands off the table and used them to cover her arms. Her eyes were furtively skimming around them, looking for anyone who might be listening as her breathing pattern became erratic. A little bit more of this and she'd probably pass out with hyperventilation.

"Look," he started. Knowing her, she'd probably digest this for the whole of afternoon before she could speak again. He needed to take control of the situation here. "It is what it is, okay? I'm not going to go after you or anything. Even I'm not that stupid," here Casey's left eyebrow quirked at him and he had to glare at her in return. "It wasn't something you were supposed to hear but you did anyways. Now I could sit here and lie to your face, but what'd be the point?"

She cast her eyes downwards, processing her words and thankfully her breathing rate had slowed down a little.

"I'm not going to jump you at home, here at school, or anywhere else for that matter, so loosen up a little, okay?" he asked. "Just take it as a guy you don't like liking you,"

After a few minutes of unmoving silence, Casey finally nodded, both her coloring and breathing now back to normal. "But we can't talk about this anymore,"

"Of course not," he agreed. "Oh, and another thing," he added, as an afterthought when she started to stand up to leave. "Could we like go back to that bantering bit?"

She raised her eyebrows at him.

"Yeah," he replied, now more comfortable at their situation for some reason. "Dad talked to me a week ago after he noticed the weirdness and he said that you really should stop breaking the dishes,"

She blushed a bit more at the last part but still nodded anyway. "I guess we go back to normal then,"

He nodded in assent and watched her move to another table. He ate his lunch alone, not minding the fact that he was eating alone. He was just thankful that the Casey situation was now taken care of.

-tbc-