A/N: So, this is the first story I've ever written for the LWD fandom. The idea hit me and now I can't stop thinking about it. I hope you enjoy it. Please review so I know whether or not it's worth it to continue it.

No, I don't own. Although whenever I watch the show I fangirl squee and wish I could have a Michael Seater. swoons

Best Imitation of You

Pairing: Dasey – Derek/Casey

Summary: "I'll bet that you can't be like me as well as I can be like you." Derek and Casey make a bet in the hopes of teaching the other a lesson. They end up learning some other things in the process.

--

Chapter One – How Things Are

It started out as an innocent – no. Scratch that.

It started out as a typical Derek-Casey encounter.

"Unbelievable! You selfish jerk!"

"Can I help you?"

Casey held up the empty container of milk, a furious look of rage contorting her face. Derek sat on the kitchen counter, calmly spooning up mouthfuls of his morning cereal.

"Yeah, Der-ek. You can share some of the milk that you've unjustly hogged to yourself."

Taking another bite, Derek laughed. "You want some recycled milk from this bowl?" He held the bowl out to her, inviting her to take it.

"No," Casey seethed. "I want the other milk. The milk you've poured into a glass. The last of the milk!"

Feigning a look of horror, Derek pulled said glass flush to his side, grasping it protectively with his right hand and balancing his bowl in the palm of his left. "Oh no, Casey. I couldn't do that. I need my morning glass of milk. Calcium helps make bones strong, you know. And, after all, I am a growing boy who needs all the calcium he can get."

Growling angrily, Casey flung the empty carton at Derek's head and lunged for the glass. Unfortunately, Derek's hockey-toned reflexes were too fast. Easily ducking out of the way, Derek held up his right foot to block Casey as he quickly picked up the glass and chugged the rest of the milk away.

"DER-EK!"

--

After two and a half years of living under the same roof, not much had changed between Casey McDonald and Derek Venturi. George and Nora would like to say that they've matured nicely and have developed into well adjusted to-be adults. Edwin and Lizzie would like to say that they've become closer as step-siblings and even as friends. Even Marti would be able to point out these horrendous lies.

No matter the mistakes the two teens have experienced together, the laugh out loud memories shared, or – don't dare to mention – the selfless sacrifices they've made for the other, the cold hard facts proved that with all these points shoved aside, Casey and Derek were not meant to live in co-habitable harmony.

The teasing, the fighting, the rivalry, the pranks, the shouting, the yelling, oh all the yelling that Nora would wish would cease. And the endless bickering that George prayed would please, oh please find its end. Edwin and Lizzie were thankful that Casey and Derek had each other to torture, leaving the two younger siblings out of their elders' 

schemes, yet still tired of all the commotion the two created. Marti simply thought Casey and Derek's interactions were downright hilarious.

But for Casey and Derek? It was continuous, non-stop war. And neither of them were the type to surrender easily.

--

To say the least, the car ride to school was tense and filled with static.

"Enjoy your breakfast bar, McDonald?"

Casey shot a glare in her stepbrother's direction. "Shut up and keep driving."

"Such hostility at such an early time. You might want to get that checked out. You know, in case there's some infection in your brain due to high levels of annoyingness." Derek chuckled at his own joke as he slid into an empty parking spot.

Casey hastily flung open the car door, clutching her books tightly to her chest. "You don't even want to see my fully hostile – UGH!"

Derek's laughter loudly echoed throughout the car. Blushing furiously, Casey unbuckled the seatbelt that had flung her back into her seat and stepped out.

"Klutzilla strikes ag-"

SLAM

--

Sometimes Paul wonders why he didn't take that chance and pursue his dreams of shining on a Broadway stage. What are dreams for, anyway, if you don't chase after them? But no, he just had to listen to his mother. Ever practical. Ever reasonable. Ever convincing him to take a chance with child psychology. Being a guidance counselor? It had its dramatics, it had its stage. Wasn't that good enough for Paul?

'No, mother,' sometimes he would say to himself. 'No. I am dropping out of college, packing up the hatchback and driving down to New York City to offer my many wonderful talents to the world of the stage.' But every time he got up the courage, there his sweet mama would sit and stare at him with such pride and adoration.

And so here he sat. Stuck. Every day. Listening to the problems of adolescents.

At least Casey McDonald's problems were amusing.

"It's like a never ending cycle. It must be his life goal to constantly irritate my every nerve, push all my buttons, and bug the ever living crap out of me. It's everything. All the time! No matter what."

Paul took a long draw from his coffee. It was only third period and already Casey was in his office spilling her daily Derek-related trials and tribulations.

"And even when I try to ignore it, it doesn't even matter because he just finds a new way to get right back under my skin. Like an annoying tick that just! Won't! Die!"

Casey angrily slammed her fist into her book with each enunciated word, her brow bunched and her face set in a scowl.

Sighing, Paul carefully picked the words he needed to say. "Casey, don't you think that maybe Derek's actions wouldn't be so irritating if you wouldn't, how do I say? Give him such reactionary reactions?"

Frowning, Casey gaped before stuttering, "Are, are you saying that I'm-I'm-I'm overreacting?"

"Well…yes."



"Unbelievable," Casey grumbled as she stood up and gathered her things. "I've got to go to class now. Thanks for listening."

"Casey, you know my door's always o-"

SLAM

--

It was the lunchmeat that had her concerned. Really, though, what was in those patties? It usually took about six packets of ketchup to mask the odor that made Emily's stomach turn die down enough to be edible. Wincing, Emily pushed her tray away. It was no use. She'd rather go hungry than have lunchmeat with her ketchup.

Just as she debated whether or not to purchase an item from the vending machine, Casey plopped down next to her with her own tray of lunchmeat. Emily watched with disgusted awe as Casey angrily cut up her lunchmeat and savagely shoved it piece by piece into her mouth. After five minutes of Cavewoman-Casey, Emily cleared her throat.

"Ah em."

Casey responded with an exasperated sigh, launching just a little bit of chewed up lunchmeat in the process.

"Derek?"

"Emily, you have no idea!"

"Well, I might have a slight idea, since you mention it almost every day."

Slamming her fork-clenching-fist on the table, Casey directed a glare in the direction of the bane of her existence. Derek sat with Sam, Ralph and a few of his hockey teammates a few tables over. Every so often the table would laugh lightly as the boys told stories and recited jokes.

"There has to be a way to get Derek to learn his lesson."

Emily carefully placed a hand on Casey's arm, bringing her friend's gaze back to her.

"Casey," she began, patting the other girl in a concerned manner. "Dear, dear Casey. Don't you think you've tried this route already?"

"But!"

"Maybe Derek is just going through a phase."

"A two year phase?"

"Or maybe this is how he shows his step-brotherly affection. Like they say, 'How do you know if someone cares if they don't tease you?'"

Casey raised her eyebrow. "Or maybe Derek is – "

"Hey McDonald! Here's some milk to make up for this morning!"

At that moment, a carton of two percent sailed across the three tables between Derek and Casey, arching up over the heads of watching students, and gliding gracefully down to land perfectly.

Right onto Emily's ketchup covered lunchmeat. Which instantly splattered all over Casey's shirt and hair, sprinkling only lightly on a ducking Emily's face.

" – a big fat JERK who's out to get me!"



--

As Casey scrubbed frantically at the red stains on her shirt in the girls' bathroom, her mind began immediate plottings of retaliation.

Get back at Derek. Get back at Derek. Get back at Derek.

Honestly, sometimes Casey thought that giving Derek a taste of his own medicine would hopefully make him see the light. Like, if Casey talked and acted and abused Derek in the same way Derek did everyday and to everyone else – especially her – then maybe, just maybe Derek would learn his lesson.

And that's when it hit her.

Staring at her face in the mirror, Casey smiled wide and said to herself, "You, Casey McDonald, are an absolute genius!"

A genius with ketchup in her hair, she thought grimly as she hastily tried to wipe away the last of the condiments covering her.

--

Unlocking the door with one hand and pushing the door open with one foot, Derek stepped into the threshold of an empty home. What a way to start a Friday night. No Dad. No Nora. No Edwin, Lizzie or Marti.

Too bad the worst of them all was following him through the door.

Not that Derek was completely revolted by Casey's presence. It was the 'holier than thou' attitude, her know-it-all ways, her keener instincts that all consistently reminded him of his numerous flaws – flaws that he considered more endearing than endangering.

Trying his best to ignore the girl behind him, Derek strolled into the entrance way, threw his backpack to the floor and made a beeline for the kitchen. It was officially snack time, and Derek had a perfect date with a delectable bowl of chocolate pudding – ooh la la!

Hearing a yelp back by the door, Derek turned his head in time to watch Casey stumble over his perfectly placed backpack. Papers flew and books fell as Casey's arms rushed to steady her balance by grabbing for the wall.

"Der-ek! Don't just leave your stuff in the middle of the entrance! Why can't you put things where they belong?"

"Yes, Wendy," he sighed, sarcasm leaking into every word. "Wherever would I be without your words of wisdom?" Derek continued walking into the kitchen and pulled open the door to the fridge. "I'm afraid I'd be nothing but a – " He grabbed the Tupperware container of pudding and shut the fridge with his hip. "Lost boy."

Popping off the top, Derek immediately stuck his mouth into the bowl and sucked in three spoonfuls-worth of pudding. Casey arrived into the kitchen in time to watch as Derek slurped up half of the bowl's contents.

"Ew. That is utterly disgusting. Don't you know how to use a spoon?"

Derek came up for air, licking away most of the chocolate that covered his lips. "And don't you know how to let other people live their own lives without micromanaging or controlling their every move?"

"Well, at least I'm considerate enough to offer my opinions and advice so that people can live their lives with more thought and organization."

"And at least I'm living life the way I want to. With lots of fun. Messy, chocolaty fun."

To prove his point, Derek licked up the last of the pudding.

"Delicious. Moment wouldn't have been the same if I had used a stupid spoon."



"Someday, your non-spoon-using antics are going to screw you over. You can't always take the fun route, you know. Some things require effort and work." Casey waggled her fingers in Derek's face, pushing past him to grab a glass of water.

"Yeah, well, when I get there I'll find a way to make the moment an as-pleasant-as-pudding one as I can. And if I can't," Derek paused to toss the empty Tupperware bowl into the sink. "I'll just blame it on you and your super ultra skills of sucking the fun out of everything."

He smiled a Cheshire cat grin at her as she sipped her water, shooting an unimpressed glower at him.

"Dishwasher, Derek."

"Shut up Casey."

Throwing her empty hand into the air, Casey let out a frustrated cry. "Who am I kidding? Derek Venturi could never be a rule-abiding, straight forward human being with thoughts and concerns for people other than himself." Casey took a step closer to Derek, jabbing a finger into his chest. "You couldn't be as unselfish or as successful as I am."

"I'm successful!"

"I'm not talking about getting dates or hitting pucks, Derek. I'm talking about things that matter."

"Like what? Grades?"

"Yeah, Derek! Grades, teachers, essays, tests, our parents, our impressions on our siblings, our daily actions. All these things matter more than how many times in a row you can burp!"

"Twenty-seven, thank you very much. And I think you're cracked."

"What?"

"You heard me." Derek took a step closer to Casey, bringing their faces inches apart. He stuck out his own finger and pointed it straight at her nose. "And you know what? I don't think you could be as care-free or as life loving as I am."

"Because it's that difficult to be a slacker with no moral code of conduct."

"And because it's so difficult to suck up to teachers and parents and walk around telling other people what you think they should do to better themselves and the world around them."

Derek and Casey both dropped their fingers to cross their arms.

"You know what McDonald? I think I smell a bet."

"Sure it's not your lack of personal hygiene?"

"I'm ignoring that. Instead, I'm going to challenge you."

"This ought to be good."

"I'll bet that you can't be like me as well as I can be like you."

"For how long?"

"Three days."

"Ten."

"A week."



"Done."

The two teenagers smirked as they began planning all the ways they were going to beat the other.

"Derek?"

"What, ready to give up already?"

"You've got chocolate all around your mouth."

--

to be continued…