A/N: Soooooooo sorry for the extremely long wait! I just feel like I'm always busy. I had some trouble writing this one too…I knew what I ultimately wanted to happen, I just didn't know how I wanted to get there. But, anyway, here's the final chapter! Finally!

Huge thank you to everyone who reviewed! It means a lot to me that you guys stuck with me.

Disclaimer: I don't own Life With Derek.

Casey didn't know what to think.

Her stepbrother, who she used to hate and with whom she had recently been sharing kisses with, had just expressed his not-so-brotherly feelings to her.

But she still liked Sam. She had a date with Sam on Friday. He was her boyfriend. Derek was her step-brother.

It could never work between her and Derek. They argued, they fought; he infuriated her. Until recently, they hadn't been able to be in the same room without arguing. Before the kissing lessons.

And so on the following Friday afternoon, Casey found herself out with Sam once again. It was possibly one of the most potentially fun dates they'd gone on together, a trip to the annual carnival, and yet she couldn't seem to get her step-brother's deep brown eyes and mischievous smirk out of her head. He had an annoying habit of appearing inside her head at the most inconvenient times and refusing to leave.

"Wait here," Sam instructed her. "I'll go win you one of those big teddy bears."

Casey watched her boyfriend as he shot balls at a pyramid of stacked bottles, a determined look on his face. She loved how he could be so romantic and so sweet. She couldn't imagine Derek doing something like this.

"Here you go, sweetie," Sam announced as he approached her once again, a huge brown teddy bear in his arms.

"Aw, thanks," Casey said, kissing him briefly.

It was things like these that she'd always dreamed her boyfriend would do.

So why was she still not satisfied?

After Sam drove her home that evening and kissed her on the porch, she went upstairs for a refreshing bubble bath. She wanted to clear her mind and escape from her problems for awhile.

But the sight that greeted her when she reached the top of the stairs made her stomach drop and her breath catch in her throat. It was Derek, crossing the hall to his room after a shower, clad in nothing but a towel around his waist. Water dripped from his hair onto his exposed chest. His eyes caught hers, and she found herself unable to look away.

When he reached his bedroom, the connection was broken. He closed the door without looking back.

oooooooooooooooooooooooooooooooo

"Sam, I have to tell you something. It's not working out between us. You see, when we first went out, I'd never kissed anyone before, so Derek offered to teach me. We've been kissing behind your back ever since, but now I think I've fallen in love with him…" Casey kicked her dresser in frustration. "No, that's not right." She tried again. "Sam, you're sweet, but I'm leaving you for my step-brother. Argh! Why can't this be easier?"

She sighed and flopped down on her bed. She supposed she'd just have to wing it.

oooooooooooooooooooooooooooooooo

Derek was rather dismayed when he found out that Casey would be tagging along to his hockey game that Saturday. He didn't want her there. He'd bared his feelings to her, feelings she didn't reciprocate, and now he just wanted to avoid her for the rest of his life.

Oh well, he thought bitterly, she'll just go fawn over Sam anyway.

The ride there was an awkward jumble of George and Nora trying to engage everyone in song while Casey and Derek managed to sit as far away from each other as possible and ignore each other.

When they arrived, George and Nora took Edwin and Lizzie to go find seats, and Derek went to the huddle of players preparing for the game, irritated to see Sam heading past him in Casey's direction. He watched from afar as they took Marti to buy a drink from the vending machine. He imagined they were a family, the three of them. They'd be ecstatically happy, like on a sitcom. Derek would never be part of the equation. He supposed maybe he wasn't really the marrying type anyway. Everyone expected him to be a player forever. Someone like him wasn't meant to settle down.

"Hey, Derek!" Great. Now Sam was beckoning him over. Reluctantly, he trudged toward them.

"I was just telling Casey how we're going to cream the other team today. Then we'll be in the finals. Right?" Sam looked to Derek.

"Yeah, sure." He avoided Casey's probing eyes.

"So, Casey," Sam started, "Want to go out for lunch to celebrate when we win?"

"Casey loves Derek!" Marti piped up.

"Marti!" Casey looked from her to Derek to Sam, an alarmed look on her face. Sam looked at Casey, question and confusion etched in his features.

"It's true!" Marti exclaimed. "I saw them kissing!"

"Casey, what—" Sam let go of her hand.

"Marti," Casey looked shocked, "how did you—"

Before Marti could respond, Derek picked her up and clamped his hand over her mouth. "She's joking. It's nothing. Right, Casey? Ha ha." He put on a cheesy grin.

"I—no." Casey sighed. "Sam, listen, I—"

"No!" Sam interjected. "Casey, I thought I could trust you! I thought you were different! But you're not. You're like every other girl in the entire fucking world who falls for Derek Venturi. And you guys live in the same house. I can't imagine what you must have been doing when I wasn't around. 'Oh, don't worry about Sam. He won't find out.'"

"Sam, this isn't how I wanted this to happen."

"So you were just going to carry on doing it, because you knew I'd never find out."

"No, I just—"

"Whatever. Save it for someone who cares. I've got a hockey game to get to. We're through." With that, Sam stalked off toward the rink.

When Derek looked back, he barely got a glimpse of Casey's face as she turned and ran out the door crying.

For a moment Derek stood frozen, torn between running after Casey and beating Sam to a bloody pulp.

Turning decisively, he walked over to his family to drop Marti off before making his way toward Sam.

Sam, who was in the middle of angrily putting on his hockey gear, noticed Derek approaching. "I don't want to talk to you either," Sam stated. "You betrayed me as much as she did." He turned so that his back was to Derek.

Derek walked around to the other side of him, but Sam promptly turned around again.

"She did it for you, man," Derek said, exasperated. When Sam still didn't turn around, Derek turned on his heel and walked away from the rink, toward the door.

"Derek, where are you going?" He glanced back to see his coach looking annoyed and the rest of his family wearing confused expressions.

"Come on!" the coach yelled. "We have a game to win!" Derek looked from him, to Sam, to his parents and siblings, to the rest of his teammates.

Shaking his head, he pushed the door open and stepped out into the rain.

He found Casey in the playground a couple blocks away, absentmindedly swinging back and forth slightly on a swing. Her clothes were soaked through and her head was tilted down. Wordlessly, Derek sank down into the swing next to her. Casey made no indication that she knew he was there, but somehow Derek could sense that she was aware of his presence.

Suddenly, after several minutes of silence, Casey spoke.

"What do you do when you know something is wrong, but it somehow feels right?"

Derek looked over at her, her hair darkened from the rain and her eyes smudged with mascara. She looked so vulnerable, and yet Derek knew she was stronger than she appeared.

"Honestly," Derek replied after a moment, "I wish I knew the answer to that question."

At that, Casey leaned toward Derek, and, before he could register what was happening, she crashed her lips against his. One of his hands reached up to cup her face and the other wrapped around her back to hold her against him. He could feel her trembling, her hands tangled in his hair and her lips doing wonders to his own. This wasn't like all the other kisses they'd shared; it was new and exciting, a preview of what was to come in their newfound relationship.

Finally they broke apart, breathless and with swollen lips. Derek slipped his hand into Casey's, entangling them together.

"Shouldn't you be at the hockey game?" Casey asked, rubbing her thumb against to top of his hand.

Derek shrugged. "They'll do fine without me."

Casey laughed and tipped her face up to the sky, watching the rain fall. When she looked down again, a joyful expression on her face, Derek couldn't help but lean forward and kiss her once more.

oooooooooooooooooooooooooooooo

"So what does this mean for us?" Casey asked later as the two of them walked home, hands entwined.

"What do you want it to mean?" Derek responded.

"Are we…a couple?"

"Do you want us to be?"

"Do you?"

"I asked first."

Casey hesitated, studying Derek's expression. "I'd like that."

"Me too," Derek said, squeezing her hand. Casey smiled.

"So, I've been wondering," Casey said, grinning at him, "that whole kissing lessons thing…it was all because you liked me?"

"Now, let's not go inflating your ego even more." Derek grinned back.

"Look who's talking! You have an ego the size of Canada!"

"But you love me for it."

"Do I?"

"You do."

And so their relationship began, an unlikely romance which had blossomed between step-siblings. Of course, they still bickered; it was to be expected from two very opinionated and stubborn teenagers. However, this passion was also explored in other ways…a passion which burned brightly for months to come.

A/N: So, did you like it? Was it worth the wait? The story is finally complete. From now on I'll probably mainly be posting one-shots. So be watching for my next story.

Reviews are still greatly appreciated! Thanks again to everyone who has kept with me!