Derek:

He honestly felt bad about calling Casey a name. He felt bad for laughing at her, too, when she fell; his first instinct had been to run down and help her up, but that would have caused even more problems. He felt bad for a lot of things, but he couldn't make himself stop.

He was either doing or saying things that would get her attention and all riled up or he was saying mean and hurtful things to avoid saying what was really on his mind. The moment he'd seen her at the rehearsal dinner he had a realization: he could not be in love with his step-sibling. So, he did everything he could to not care about Casey McDonald.

Except he did. Care, that is. When Sam mentioned that Casey was cute, he wanted to punch his best friend and tell him that Casey was beautiful and he didn't deserve her… not that Derek really did these days, or to begin with if he was being fair.

He felt bad for a lot of things, and he felt even worse with Sam there giving him the guilt trip. Still, even with the guilt it was easier to make fun of her and ignore her at school. He pranked her at home, anything to get her to hate him, and now that he started he couldn't make himself stop. It was the only interaction that he could have that would be acceptable by their parent's standards. Everytime he wanted to kiss her, he found a way to irritate her instead.

It was a sick cycle.

He shouldn't even feel bad for all that he's done to Casey, because that just reminds him that he has feelings for this girl and that's a reminder he can't have… so then he does something else and she's yelling his name in the way only she can…

Derek tuned Sam out, deciding that by ignoring his friend he could ignore the guilt.

8888

That night at dinner, when Lizzie sat down and said that Casey wouldn't be down because she didn't feel like eating. She seemed only slightly concerned, mostly believing her sister to be dramatic. Derek felt a pang in his chest and cursed the day he had ever met Casey at that party. He'd never really felt guilt before her. "Did something happen?" Nora asked the table at large and Derek slumped a little in his chair. "Derek?"

He internally sighed and let out a snicker. "Yeah, she took a nasty fall down the stairs."

"Oh my gosh, is she okay?" Nora started to rise from her chair but the object of their conversation spoke up from the stairs.

"You are such a massive jerk, Derek." She'd been crying and he refused to look at her.

"Uh, it's my fault you can't walk and talk at the same time?" The retort just flew out of his mouth, with more snark than he wished. He did look up at her then and he wished he could just take her in his arms, hold her, and find a way to make everything okay.

It just couldn't be done. He argued with her, instead(and really every time was a reminder of that night they first met) but when she stared at him, sadly, no anger in her eyes he wondered if maybe she'd given up.

He knew it was his fault, but he couldn't stop. "You insulted me when I was going down the stairs, and then I fell. Now I'm the laughing stock of the school and you think that's funny?" She didn't even bother to wait for his reply before turning and storming up the stairs.

Derek exchanged a look with Edwin. "Emotional," they agreed, in unison. He felt another pang of guilt as Nora quietly excused herself to go speak with Casey.

When he met up with Sam that weekend at the park, he assumed Casey had something lame to be at and hadn't thought twice about inviting Sam over. It's not that he thought he could hide that Casey was his step-sister forever, but he could put it off a while longer. Especially when Sam thought she was 'cute'.

What he wasn't expecting, though, was for Casey to be home all sweaty from a work out, standing in their kitchen with a sliver of stomach slightly exposed. He swallowed hard when he got a look at her and, thankfully, she was turned toward the fridge and didn't see him. "Klutzilla, who let you into my house?" He asked, shocked.

Derek watched as Casey's back tightened, "I live here." She snapped, turning. She caught sight of Sam and smiled, a little. Sam smiled back and Derek glowered. "Unfortunately," she continued.

"I thought you said you didn't know her," Sam asked, confused. He just shrugged.

"Oh yeah, I forgot. Sam, Klutzilla. Klutzilla, Sam." Derek moved toward the fridge and couldn't resist bumping Casey's shoulder with his own as he opened the door. He wanted her to stop looking at Sam. The cool air of the fridge felt good and he listened to her introduce herself, properly.

"It's Casey, actually. My mom married Derek's dad." He wasn't supposed to feel good about her unwillingness to say step-sister.

"Your dad got married?" Sam asked, surprised.

"Recent accident," Derek grunted into the fridge. That's what it felt like sometimes; an accident. There was a reason he'd been keeping Sam and Ralph (especially Ralph) away from the house.

"That was some fall yesterday," Sam said and Derek let the fridge door fall with a close. He looked over and his best friend was making doe eyes at his gi… step-sister.

Casey turned pink and Derek felt a flare of triumph; that wasn't the way to win Casey over.

"You alright?" He was still smiling and Casey had started to smile, too. Derek felt sick.

"Yeah, I'm okay. I'm not usually like that; I just got distracted by some lame comment." She shot Derek a look as he went to stand beside his best friend. He was glaring back hoping it spelled 'back off' in big bold letters.

"That was a quality insult," he said feigning indignance.

"Anyway," she continued, completely ignoring him. When did that happen? "It was nice meeting you, Sam. I'd shake your hand but…" she shrugged a little and Derek felt the need to interrupt.

"You're all sweaty and gross," he supplied, helpfully. Casey rolled her eyes and started backing out of the kitchen.

She was paying attention to him again. "Derek, you're such a…" but she didn't get a chance to say because she tripped backward over the project that Marti had been painting and the young girl started crying that Klutzilla broke her house. Sam moved to help Casey up and Derek, unable to not be an ass, started laughing. It was fake, but no one would know.

"Classic," Sam muttered watching Casey who had taken off to the stairs.

"Totally," he agreed, pretending to ignore the fact that Sam was talking about him and not Casey's fall. He didn't like the way Sam was staring after where Casey had gone.

Marti was still crying about her house that she'd worked on all day and her voice was starting to get high pitched; "Aw, don't worry, Smarti. I'll help you make another one, tomorrow." He ignored Sam who was now staring at him and when he asked why he hadn't mentioned the step-family he just shrugged. "She's an embarrassment, obviously."

Dinner that night ended in a mini food fight caused by Derek inserting his foot into his mouth… again. Not long after Lizzie was knocking on his open door. He looked up from his computer, suspiciously and gave her the go ahead to come in. She did so, slowly, and looked all around her.

"How are you?" She asked, politely.

Derek raised a brow eyeing his step-sister (this one, he could acknowledge). "What do you want?"

"It's about Casey… do you think you could stop being mean to her?"

That really wasn't something he was able to do without acting on things he shouldn't do. "I really don't see that happening." He turned back to the computer, indicating the end of the conversation, but the kid kept going.

"But she actually needs your help," Derek looked up from his computer. She needed him? The idea sent an ache of longing throughout his body and he felt, for a second, in pain.

He managed a nonchalant, "What?"

"Well, you're cool, right?" She didn't wait for confirmation. He was going to assume it was because it was obvious. "Maybe you could get the other kids at school to leave her alone?"

Derek leaned back in his chair and considered Lizzie. "Well, even if I could help, which I wouldn't, she wouldn't accept my help, which I'm not offering. He'd probably find a way to help her out, without directly helping her but it would ruin his rep for anyone to find out.

Lizzie grew more insistent, "But you have to!" For such a small person, she was kind of scary.

"You're new here, so I'll forgive you for talking to me like that." Don't show fear. Don't show fear. Don't show fear.

"You don't have to forgive me, just help Casey."

"Why do you care so much?" He snapped. He cared, sure, but he made sure to make it look like he didn't. Casey was the one moping around, making it obvious there was something wrong. His dad and Nora chalked it up to the move, but he knew better.

Then again, they couldn't hear when she cried at night.

"Because she's my sister." Lizzie snapped back and Derek scoffed.

"That's all you've got. Sorry, kid."

"She's your sister, too." Lizzie said and without another word, turned and left the room. Derek sat, stunned. Casey would never be his sister. That's how everyone will see it, though and reality was suddenly staring him in the face.

Casey:

The brunette was sitting at her desk writing poetry, trying to distract herself from how embarrassing and miserable everything had been lately. Mostly trying to pretend she wanted nothing to do with Derek.

She'd been played; she had been in love and had believed to be loved in return, but this all proved she didn't know a damn thing. It's not that she expected her and Derek to be together, because that obviously wasn't going to happen. She just never expected to be confronted with the reality that Derek never wanted her to begin with. That he could so easily toss her aside like just like all those other girls. That he could move on so quickly and be such an ass to her; that was what she had a hard time coming to terms with.

There was a knock on her door and she let out a frustrated huff. "If that's my mom, George, Lizzie, or Marti go away." The knocking continued and she went to yank open the door in her frustration. "What?" She snapped, not expecting who was on the other side of the door.

"You forgot me," he leaned on her doorway. "And Edwin, but that one happens a lot."

"What do you want?" Even to her, her voice sounded very tired.

"I want to help you fix your rep at school." He actually sounded sincere, but he had that night at the party and Casey was immediately suspicious.

"Why do you care?"

"Well, it's bound to get out that you're my step-sister." She must have imagined the hesitation in front of that word. "If you look bad, I look bad." Of course he would make this about him. Casey rolled her eyes.

"Touching," She snapped, "but seeing as you're the one who caused my problem in the first place, forgive me when I say get out." She yelled the last two words and slammed the door closed in his face. He knocked again, and because she's a glutton for punishment, Casey answered. "What?" She snapped again.

"You think I caused your problem?" He snorted, "I think you're massively uncoordinated."

"Do you want proof? I am a very graceful person-Derek, I am a dancer. You were the common denominator in each scenario; you said something rude in both cases, making me fall. You were the one who gave me the nickname that everyone now uses at school."

"Wait a minute," he looked suddenly pained and surprised. "I just had a horrible thought." Casey raised her brows, expectantly. "Another person." He looked like he hadn't meant to say it, but it was out in the open now.

Her eyebrows went higher, "Who?"

"You don't… you don't like Sam, do you?" Derek asked, moving in close. Casey's eyes searched his face, carefully. Was he seriously asking that when he knew better?

"What?" She asked, pushing him away. His close proximity was making it hard to focus.

Derek looked smug, "Oh my god, you do." Casey felt her eyes starting to water. He was really suggesting that she was crushing on Sam even though she'd admitted her love to him. Just because he could move on that quickly, didn't mean she could.

"You are so wrong," Casey laughed, pushing him away as he got closer. "Like I would ever like, like one of your lame friends." She felt a little bad because Sam seemed like a nice guy; he picked terrible company, but then again she wasn't much better.

Standing here, arguing with Derek, she felt a little better than she had in the previous week. For a minute, sparring with him like this, she could pretend nothing had changed and the tension she felt in the air wasn't because he couldn't stand the sight of her. This is when they were at their worst, but it was also the only thing she had anymore. Maybe, she could pretend, that he didn't hate her and that he was just doing this because it was the only thing he had, too.

Derek closed the distance between them and pointed a finger, "Well, I think you do. You'd better get over it… for the sake of everyone's safety around you." She caught something flashing in his eyes. He leaned in and breathed in her ear, "Don't crush on my friends, Case."

Casey, feeling bold, which always happened when they were like this, spoke up. "If I didn't know any better," she murmured, "I'd think you were jealous." She eyed him carefully and he seemed surprised.

She raised a brow at him and he muttered, "I just don't want my friends hanging out with a keener like you." And then he turned. It may have sounded like he had the last word, but she knew she'd won that round.

Derek:

By Monday morning he was still trying to think of a way to fix things with Casey. He'd excused her clumsiness as a crush on Sam. He hoped it wasn't true but knew regardless Casey would have denied it. What had got to him was her comment on this summer. It wasn't direct, but it was enough and he had thought they had an unspoken agreement not to bring it up.

Of course he was jealous. Sam was into her, he knew, and she hadn't exactly derailed Sam's attempt at flirting. Could she not see how much he was hurting without her? He truly loved her… not that he'd been exactly showing it, but that was the point.

He knew for sure he had to do something when he saw Casey at her locker, talking to some girl who seemed quite upset, and he caught sight of Emily heading toward her locker, but when she saw Casey, she turned the opposite direction. Emily was supposed to be her friend and she needed someone right now. He waited until Emily was about to pass him by, before stopping her. "Emily, right?"

Her face lit up, "Yeah." She offered him a brilliant smile.

"Why aren't you hanging out with your new friend?" He asked as his eyebrows came up. Emily's face fell.

"I was just heading to our locker."

"Well, it's the other way." He said, nodding in the right direction.

Emily nodded, reluctantly. "Right." She turned around and Derek stopped to listen to some girl, mostly so he could watch what was happening. Emily offered to walk with Casey just as some girl made a jab at Casey. It was clever but really, he was the only one who could make fun of her. Still, Emily agreed to stay by her side.

She said something and Casey's face brightened, "Aww, you're awesome." He heard Casey respond, turning with a smile. He felt his heart skip at that smile and he smiled a little to himself. The girl on his right assumed it was something she said and touched a hand to his arm. As she turned, though, she bumped into Corey.

"Hey, one lawsuit wasn't enough?" He snapped and Derek bristled.

"Butt out, Corey." Emily to the rescue.

"You leave my butt out of this," he snapped back. Derek turned completely, no longer pretending to pay attention to the girl talking to him.

"It's okay, Em." He recognized the feisty look in Casey's eyes. She was getting her fight back, or so he hoped. "You can't just sue every time someone bumps into you. And I showed that summons to my lawyer." She took a large legal looking envelope out of her backpack. "And he gave me some legal advice. He watched as she tore the envelope in half and threw it in Corey's face. It was nice seeing this side of Casey again, not the show she put on for the rest of the world.

Corey looked pissed. "Alert the stair monitors," He spoke up, loudly, glancing around to see who was paying attention. "Klutzilla is back with a vengeance." Casey's face fell a little, but she stood her ground and he was proud of her.

"Corey," Derek was walking without even realizing it. Suddenly, though, his arm was cutting in front of Casey and around the other teen. "Walk with me," he commanded, walking them in the opposite direction.

Once they'd turned a corner, Derek stopped. "So, Corey, how's the injury?"

Corey rubbed a hand on his cheek, "Well, it hurts when I sit." Derek resisted the urge to roll his eyes. Casey's face had hit Corey's ass. It's not like he'd fallen on it.

"Yeah, well, I need you to do me a favor."

"Sure, uh, what it is it?" He pretended not to be surprised, like him and Derek had always been best buds.

"Cut Casey some slack." he saw the surprise, "You see, she's my… step-sister." The word tasted foul. He would have rather said a million other things but they wouldn't have been appropriate.

"No," Corey said, shaking his head.

"'Fraid so."

"Well, don't sweat it, man. I won't tell anyone." Derek felt another stab in his stomach. Guilt, again. He had made it so bad already that people would go out of their way to ensure that no one knew he shared a house with Casey; that anyone would be embarrassed to be standing here admitting what he was admitting.

"No, no. It's cool. Tell everyone, okay?"

Corey nodded and tapped his nose like he was in on some kind of secret before turning to leave. Derek rolled his eyes behind the other kid's back. He went to catch up with Casey and Emily. "Maybe I should just tell people the effect bullying can have." Casey was saying and Derek groaned internally. She was so not helping herself.

Emily caught his eyes and was practically begging for help. Luckily it arrived in the form of Sam. Casey would never listen to him, but Sam was nice. He nudged his best friend toward Casey, "She wants to lecture the students on bullying."

"Hey," Sam said and Case turned, surprised.

"Hi." She said, and smiled prettily. He remembered when that smile was aimed at him.

"What's up?"

"I'm going to make an announcement." She grinned and Sam smiled back.

"Don't bother. Here," and he offered her his arm. Casey blushed and accepted and Sam started walking. "I'll walk you to class." Derek wanted to punch him when Casey looked surprised but smiled and accepted.

"Okay, thanks."

And a part of him was glad that she looked happy.