A/N: So, this is a one-shot, possibly a two shot, and it IS a song fic, to a song called Poetically Pathetic. You should definitely listen to it. Amber Pacific has it on their myspace and purevolume. Also, it might be a two shot because I didn't quite put in all the parts from the song that I wanted to write out. And, I'm not putting any lyrics in, cuz I don't like that too much, plus I WANT you to listen to the song. Basically, the song is about telling the one you love…that you love them. I thought the lyrics fit perfectly for Derek telling Casey, or even vice versa. Anyways, enjoy! And Please review!

Disclaimer: I don't own the show Life With Derek, or Amber Pacific's Poetically Pathetic

Poetically Pathetic—

"What are you staring at?"

Casey's question pulled Derek out of his slight reverie. They were sitting in their usual seats in the living room, him in his brown chair and Casey sprawled out on the couch, her legs propped up and a book in her hand. She was giving him an inquisitive look, confused as to why he had been staring at her.

He shook his head and scratched the back of his neck, trying to look indifferent. He had been daydreaming about her, of course. By now, it didn't freak him out. It had been long enough since he first realized that he was starting to have non-brotherly feelings towards his stepsister.

"Nothing," he answered her eventually. She rolled her eyes at him.

"Wow, you sound so convincing."

"Why do I always have to explain myself to you?"

"I guess you don't, Derek. I was just wondering what was so interesting about my face."

"Nothing that I'm interested in, for sure," he replied before standing up and walking away.

That's such a lie! he thought to himself as walked up the stairs and headed towards his bedroom.

Casey let out an aggravated sigh and then reluctantly followed him up the stairs. She stomped into her own bedroom and practically slammed the door.

"Ugh! Why is he so…!" she started to yell, but then couldn't think of any word to describe how Derek was making her feel.

It wasn't like she didn't notice that he had been acting weird around her, weirder than usual, over the past few weeks. She did notice; a lot. How could she not? He was so transparent and yet completely mysterious all at the same time. She could tell that something was going on with him, something that had to do with her; she just didn't know what it was. She tried to think about what could possibly be the reason behind Derek's sudden change. She had started to notice it after her father's visit when he had unexpectedly come back after having left for the airport. Her dad had affirmed her belief that that Derek had been the one to call him.

To say that Casey had been surprised was an understatement. She couldn't even begin to comprehend why Derek had been so…caring in that moment, but she liked it. She couldn't believe that he had thought to call her father, who he knew she loved so much and didn't see half as much as she wanted to. Since that night, he had started to be…Casey couldn't think of a word to describe the change in Derek. It seemed like she couldn't think at all when she thought about him anymore.

It was strange. She knew he hadn't changed completely. They still fought all the time, mostly about trivial things, but unlike before, there were more moments between them, moments when she had to wonder to herself where the Derek she knew was; the real Derek.

Before, they would fight, and fight, and then fight some more, and sometimes, after all that fighting there might be a moment or two when the two of them would be able to coexist peacefully. Casey liked to think of those short times as their "moments". Like, the time she had helped him at school when he had had the chicken pox. He had been an infuriating boss, especially after all she had gone through for his stupid little business, but then he had miraculously gotten her out of her suspension and he had even bought her very first cell phone for her. She hadn't been expecting that, but she had to admit, at least now, that Derek had a soft side to him. It just didn't show up too often, particularly in front of her.

Now, however, it showed up a lot more. It wasn't that he was nicer or anything. Nope, they just had more of those "moments."

He confused the hell out of her, that much was true but she couldn't pretend like she didn't enjoy his company. Not anymore, at least. Their arguments and short truces were a constant in her life now, and Casey liked consistency. It fit well in her life. She was a perfectionist after all.

Lately though, she could tell that something was different. Very different. Even more different than their extra bonding time. She wasn't quite sure what it was, but she just had an inkling. There were moments when she just wanted to ask him what was up, just stride into his room, much like she always did, and ask him point blank, "What is going on with us?" But the thing was, she was too scared to hear his answer. Even more though, she was scared that he wouldn't answer her and then she'd feel embarrassed…Casey hated feeling embarrassed.

She decided that she was just going to ignore her feelings, her inklings. If something was up, she would wait for Derek to speak up, for him to make the first move.

Casey raised her eyebrows at her own thoughts.

What exactly do I want him to do? Or say?

She still wasn't sure. Except that she was…she was just too nervous to admit what she knew she wanted from him.

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Derek was pacing. He just kept walking around in circles in his room. He wouldn't be surprised if he burned a path onto his somewhat tidy, at the moment, carpet.

She was driving him insane. She being Casey, of course. Ever since he had caught her crying in the kitchen the day her father had come to visit, he had started to notice some things. Well, 'some' wasn't the correct word. He was noticing a lot of things. Things that he should have been aware of from the very beginning, the beginning being the first time he had laid eyes on Casey. He should have realized back then that it would be impossible for him to hate her, or at least be annoyed with her like he tried so hard to be. She had gotten under his skin right when he met her and hadn't left since.

He realized that every single thing he did to annoy or hurt Casey, every single fight he picked and fought with her, every time he got mad at her for something, it wasn't just some sibling thing. He realized now that he had fallen for her the moment he met her. All those things he did were stupid. He was stupid.

When he thought about it, he wondered how it took him so long to realize these things, to realize that the reason he was so hard on her was because somewhere, subconsciously, he liked her. He liked her a lot. He was like a little kid teasing and pulling the pigtails of the girl he liked on the playground. That was his way of letting her know how he felt about her.

Of course, he didn't realize any of this while he was doing it. And apparently Casey hadn't either. He hadn't yet decided if that was a good or bad thing.

How did I not know all of this earlier? he thought.

It was so obvious to him now. He kept having flashbacks in his head, flashbacks that included scenes of him and Casey; him and Casey fighting with bathroom products; him and Casey dressing up as a married couple for a school project; him and Casey teaming up together to get her out of a late science grade; him and Casey arguing about him going on a date with Emily, and one of his personal favorites, him and Casey practically grinding with each other during their Clash of the Bands performance. That was one of the only times before his ignorance had been lifted that he had actually admitted to himself that Casey was a little cooler than he let on. That, and hot.

She was so hot that night. Not to mention when she dressed up as Babe Raider.

He smiled at the thought of her dressed up as his favorite video game heroine. He continued to think of more "moments" between them when he was interrupted by a voice.

"Derek?" asked a quiet Casey as she walked into his room. "What are you doing?" she asked when she saw him pacing. He stopped moving.

"I could ask you the same question." Casey let out a weak laugh.

"Well…" she tried to think of a reason why she had come into his bedroom.

"Yeah? What is it?" he asked, but then winced. He didn't mean to sound so mean. It was hard to change sometimes.

Casey frowned.

"Never mind," she said and then turned around to walk away. Derek just watched her leave his room. Since she hadn't answered his question, he still didn't know why she had come.

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"Why did I just go in there?" Casey asked herself when she was settled back in her bed, hugging one of her pillows.

I already decided that I wasn't going to drag anything out of him, so why did I just go in there? she asked herself, this time not out loud.

"Whatever."

She got up and found her pajamas. She was ready to go to bed. It was a Thursday night and she didn't want to stay up too late on a school night.

Right as she was about to put on her pajama top, her door started to open. She let out a small squeak and hastily put her tank top on. Derek was the only one that didn't knock.

"Jeez! I'm trying to change in here," she said when she saw him standing in her doorway. His mouth was open and formed a little 'o'. Casey just rolled her eyes. She did that a lot around him.

"Oh, calm down. It's not like you saw anything important," she said and then walked to her bed and sat down, grabbing her pillow once more and hugging it to her chest, the only sign she showed that she wasn't as calm about what just happened as she let on.

"Why are you here?" she asked him hurriedly.

"Uh…to talk to you," he answered lamely. Casey lifted her right eyebrow at him.

"Talk. You want to talk?"

Jeez, what is with him?

"Yeah," he said, nodding his head meekly.

"Okay, fine. Let's talk," she said. She moved her pillow and placed it so that it was lying across her lap. Then she just stared up at him. He didn't move from his spot in the doorway.

"Can I come in?" he asked. Casey nodded her head once and made a face that clearly meant, "Duh."

As he walked into her room, slowly, Casey's thoughts ran wild.

Oh man, why is he in here? Are we really going to talk? Is he going to tell me what's been up with him? With us? Is he going to confess something? Do I want him to confess what I think he's going to confess?

He was standing at the foot of her bed now.

"You can sit down," she said, and patted the spot in front of her. He sat down, a bit awkwardly, on the end of her bed.

"So, what did you want to talk about?" she asked timidly. The thoughts in her head turned from a hundred questions to just one mantra, one question that she tried so hard not to let herself think, even when she was thinking about him.

Does he like me? Does he like me? Does he like ME?

"I just wanted to talk to you about stuff."

"Stuff?"

"Yeah. Stuff that's been going on lately."

"What about it?"

"Well…I don't really know how to…start, or explain what I'm trying to…explain," he said clumsily. Casey just gave him a soft smile, hoping that if she looked composed, then maybe he would feel less uncomfortable.

"Just try," she said gently.

Derek didn't know what to say to her. He just knew that he had to tell her, or at least show her in some way how he felt. How he had been feeling for weeks, hell, months. He wanted to enlighten her with all of the memories he had of them, wanted to tell her what he realized they meant.

Oh God, Casey! I'm pretty sure I'm in love with you and I know it might be wrong since were stepsiblings, but it's just how I feel. One day it just hit me, the way I act around you, the way I treat you? It's because I like you. Well, now I love you. How do you feel about that?

That's what he wanted to say to her, but he couldn't. He knew she'd freak out and that is so not what he wanted her to do. He wanted her to see things from his perspective because that was the only way that she would ever be able to feel the same way about him.

The whole time he contemplated what to say to her, Casey just watched him, waited patiently. When she was about to give up on him, deciding that he would never tell her the things she wanted him to, she made to stand up and get off of her bed. She couldn't handle being so close to him if all she was going to do was stare at him while he said absolutely nothing to her.

He grabbed her hand right before to stood up. She was surprised; surprised that he was stopping her, surprised that he was touching her, holding her hand.

He pulled her back onto the bed so that now her pillow was on the floor and she was sitting right next to him. He turned so that he was facing her.

"Casey, I've thought about a million things to say to you, a million ways to let you know what I'm feeling, but it's just so hard for me. I've never felt this way before," he admitted. Casey looked confused.

"How exactly do you feel?" she asked. She had to let him say it.

"I feel like…" he started, but then gave up.

Ah hell, who cares? he thought, right be fore he grabbed her face and pulled her closer to him. He captured her lips with his own and gave her a fierce kiss, a kiss that he'd wanted to give her since the day he met her, a kiss that he didn't know he wanted to give her until a few months back.

He was surprised when she didn't immediately pull away from him. He just held onto her tightly, his right hand moving to the back of her head, loving the feeling of her long, silky hair.

Maybe she feels the same way? he asked himself, but then she pulled away.

Her face was flushed and her lips were extra red and she was breathing heavily.

"Um, what does that mean?" she asked him. Her mind was reeling.

He kissed me! He kissed me!

"It means that everything is going to change now," he answered.

"Change?"

"Yeah. If you want it to."

"Change to what exactly? I need to know."

"It means, basically…that I love you." Her eyes widened at this admission. He laughed at her reaction.

"What?" she asked.

"You heard me. Don't make me say it again."

"I think you need to." He sighed and took both of her hands into his.

"All right. Casey MacDonald, I am in love with you. I think I've been in love with you forever, I just didn't realize it until a little while ago." He didn't take his eyes off of her for a second as he said this. He loved her eyes. They were so different from his own, so light, so blue, so beautiful. He waited for her to say something, but it seemed like she was speechless. He couldn't help it, he smirked. "What? Say something, Case. I know you're not one to keep quiet for too long."

"This is really sudden," she finally said.

"Yeah, maybe, but that doesn't change the fact that that's how I feel. And I'm pretty sure that you feel the same way because if you didn't, we wouldn't have been able to have that amazing kiss that we just shared." Casey rolled her eyes once again.

"I don't know about that. Maybe I'm just a really good kisser."

"Then I guess I'm really lucky," he replied.

"Wow, I can't believe how cocky you still are."

"Hey, all I did was confess my love for you and you still haven't reciprocated your feelings, how am I supposed to act?"

"Wow, that was a big word," she said, impressed.

"I know. And I'm sorry that I didn't read you some poem or sing you a song or anything like I know you'd like. I just couldn't stand it anymore. I had to let you know."

"Yeah, I'm beginning to get that," she said smugly, but she still didn't say anything of significance.

"Casey! You're driving me crazy. Just tell me what you're thinking!" he practically shouted at her. Her eyes widened once more at his eagerness, so she did the only thing that she could think of.

She leaned forward, placed her mouth over his, and kissed him slowly. Then, she let go of his hands and put her hands on his shoulders. He didn't move, so she leaned in even closer to him and moved her arms so that they were wrapped around his neck, deepening the kiss at the same time.

That was all Derek could handle without responding. He grabbed her waist and picked her up. She let out a surprised little cry, but he muffled it with his own kiss. She was now in his lap.

They kissed for about a minute before he pulled away.

"Casey, you're still killing me. Will you just put in words how you feel? For all I know, you're just using me for my body right now." She smirked.

"You are so full of yourself," she said, and then kissed him again.

"Case, I'm serious," he said, once again pulling away.

"Derek, how stupid are you? How could you not know how I feel about you right now?" she asked. He shrugged his shoulders and grinned.

"Fiiine," she relented, knowing that he wasn't going to give up until she herself spoke her feelings out loud.

She placed her hands on either side of his face, keeping her gaze on his dark, chocolate colored eyes. "Derek Venturi, I'm pretty sure that I am in love with you," she said, then kissed him. And he kissed her back.

A half minute passed before he managed to get out a ragged, "Pretty sure?" against her lips. She just continued to kiss him.

"Really sure," she answered. He pulled away.

"Good."

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A/N: So, do you think that's a good ending? I tried to incorporate my favorite Dasey moments, if you didn't notice. There are a lot, and so many more that I didn't put in. I mean, seriously. IT'S SO OBVIOUS! How could they not get together?