A/N: This idea just sort of came to mind. Nothing more than brother/sister love. I don't know if Derek's mom is married, but she is in this story.

Disclaimer: Don't own National Treasure or Life with Derek

Casey was done talking with her mom. All she wanted to do now was curl up on the couch and watch a movie, just to get her mind off the events of what had happened during the day. She took out the Oreos and peanut butter and began to search for some movie to watch. She found several movies she thought would be good, such as Spiderman, Pearl Harbor, and Titanic, yeah they weren't her normal types of movies to watch, but she still liked them, she then realized an underlying theme in them, the guy not getting the girl, something she was not in the mood to see right now. She then spotted another movie she enjoyed, National Treasure, yes made more towards those who were Lizzie and Edwin's age, but it was still good. She pulled the disk out of the case and popped it in. She was ready to watch her movie, relax and forget about the day and just as she was settling in, Derek came storming into the house.

"Hey." He said sort of angrily as he stole one of her cookies and plopped down into his chair.

"Could you please go be angry somewhere else?" she shot back.

"Uh, let me think, no." he responded.

"Please go away, Derek."

"No, so whatcha watchin'?" he asked, turning his attention away from his anger and towards the TV.

"None of your business. Now go away."

"Whatever." He said as he got up. He was in no mood to deal with her attitude right now. He had just gotten into the biggest fight with his girlfriend, probably the biggest he's ever gotten into with a girl, and it had really gotten to him.

"You can watch it if you really want." He heard Casey say as he reached the bottom of the steps.

"What so you can bug me?" he said, sounding agitated.

"I'm serious, Derek." She replied and she really did sound earnest, like she really wanted him there. He decided that it wouldn't hurt anything so he went over and hopped into his chair, besides the movie might take his mind off things.

"So what are we watching?" he asked, this time sounding a bit nicer.

"National Treasure, the only thing that doesn't deal with broken love." She said sighing.

"Good." He replied laughing, he then stopped when he thought about it.

"Wait, what's with you and not for a broken love movie? I thought you liked those sorts of movies where the guy and the girl have a fall out and then something happens?" he questioned.

"Nothing, just not in the mood for it." She replied, but Derek caught something in her tone.

"Is that really the reason?" he asked pointedly.

"Derek, your mom remarried right?" she asked after a minute or so of thinking. The question actually shocked him a little.

"Um, yeah, why?"

"How did you feel about it?" whoa, she was getting a little too personal for him.

"I wasn't happy about it, if that's what you're getting at."

"Ok, so it's alright you think to be angry at a person if they get remarried or are planning on it?"

"What's going on, Case?" he asked. He knew something was up and he didn't want her beating around the bush about it.

"Promise no teasing?" she asked looking at him. She was being serious and also Derek saw something in her face so he knew he couldn't tease her, especially if he had an idea of what she was getting at.

"Promise."

"Well, I kind of found out that my dad's getting married again. Let's just say I'm not too happy about it." She said honestly as she put some peanut butter on an Oreo.

"Eh, that's alright. Hey this is a good part." He said focusing his attention on the movie. He liked Casey, she was a good girl, but one there was the fact that she was his sister, correction, step-sister, and plus, he wasn't really into talking about things like this.

The two watched the movie for a while and as they did so, Derek kept taking glances over at her. Each time he did he never one full smile come, even when the weirdly funny parts or lines came up, he didn't want that, especially if it hadn't been him to cause her being upset. It was then that a thought came to mind. He remembered when he'd been upset about his mom, Marti had known something was wrong and her job was to fix it, so she had tickled him. He'd laughed the hardest he'd laughed in a while and it had helped him feel better.

Derek took one more glance over and put his plan into action. He hopped out of his chair and onto the couch where he then preceded to dig his fingers into her ribs.

"Derek, what are you doing?" she asked between gasps for air and laughter.

"What I know will help." He said smiling. He then sat heavily back against the couch when he felt she was good.

"I ought to kill you, Derek." She said as she too sat heavily against the back. She wasn't angry when she said; she was smiling. It actually made her laugh more when she realized who had made her feel better. He only smiled.

"Thanks Derek." She said before letting out a yawn. Derek pulled a blanket out from behind him that was on the couch and handed it to her.

"Here, it's cold." He said matter a factly. She smiled a grateful smile at him as she took it and wrapped it around herself. The two then turned their attention towards the movie and after a minute a thought popped into Derek's head.

"Oh, Casey?"

"Hmm?"

"You mention this to anyone and you will pay." He said.

"Alright." She said, just shaking her head. Derek was so hard to figure at times, but he was a good guy. They then left it at that and watched the movie. Casey fell asleep a little before the movie was over, with her head lying on Derek's shoulder. He didn't bother to move her, because to be honest he was tired himself. He fell asleep not long after Casey and that's how they were found the next morning. Nora and George had quickly gotten the camera and taken a picture of them. Casey was asleep on Derek and Derek had his arm around her and the blanket over both of them. They looked so peaceful.

THE END