A/N: Hey! I'm back with the third and final part of this trilogy. This chapter is very similar to the last chapter. Just gives some more background and Casey's point of view. Oh, and because I wanted some dialogue, I added a flashback. Enjoy!

Disclaimer: Um yeah. Don't own Life with Derek. Go figure.

"Yes, Casey. I think you should marry Noel." Those words answered a question that had been on Casey's mind for nearly 8 years.

Casey McDonald was in love with her stepbrother, Derek Venturi. No one could have predicted that Casey would ever fall for the obnoxious teenaged boy she was forced to live with when her mom married his father, most of all, Casey. She disliked him from the moment she laid her eyes on him and his infamous smirk. They were total opposites. She was organized, thoughtful, and took school seriously. He was messy, selfish, and couldn't care about school any less.

At least, that was what Casey thought about Derek at first. After living with Derek for a little over a year, Casey realized that Derek had more to him than what he showed on the outside. Sometimes, he actually showed signs of caring about others. He would even swallow his pride and do a thing or two for Casey that was in her best interest.

This was obvious at the beginning of their junior year. Turned out that Max had been cheating on Casey with his ex-girlfriend, Amy. The news had been all over the school and Casey had been humiliated and even more devastated. Casey remembered the day where Derek showed he truly cared about. It was that day she started to develop her feelings for Derek.

(Flashback)

Casey walked into Smelly Nellie's after a particularly bad day. It'd been 3 weeks since she broke up with Max after finding out he was cheating on her, and people were still coming up to her asking odd questions about the break up. The questions had gotten weirder and weirder with every passing day. That day, 3 people had come up to her, one asking if it was true that Max had been engaged to Amy for 2 weeks behind Casey's back. Casey decided she'd go to Smelly Nellie's to just relax.

Casey sat down at a table. Derek was working at that time and came over to her.

"Hey. You look kinda down. What's up?" Derek asked her, walking up to her table and sitting down across from her.

Casey sighed and folded her hands on her lap. "Just, you know. Today wasn't a very good day."

"Well, we can change that! We can start with me waiting on you! You always love that." Derek said standing up.

Casey laughed and for the first time that day, her eyes lit up a little. "That is true. I find it quite enjoyable when you have to listen to me."

"Yeah, you might. You don't know how much it pains me to actually listen to you. It goes against my nature to do the exact opposite."

"And I find it entertaining to watch you struggle."

"Oh, well look at that. Ms. Goody-Two-Shoes likes to watch people in pain. Not very nice is it?"

"Hey, I never said I was an angel. Most people just assume that."

"Pshh, yeah? Well I know better. I know how you think in there McDonald."

"Oh do you, Venturi?"

"Yes I do." Casey smiled at Derek while he smirked back.

Derek cleared his throat. "So Ms. McDonald, what would you like today?"

Casey picked up the menu and pretended to decide what to order. "What would you recommend?"

"You want me to recommend you something?"

Casey laughed. "I know it's kind of risky but-" then she stopped mid sentence. Her eyes were focused on something behind Derek.

He turned around to see Max and Amy sitting at a table, holding hands.

Derek inwardly cringed and turned back to face Casey. The laughter that was in her eyes moments ago was gone, replaced with dull emptiness.

"Um… I'll just have a glass of water please." Casey said without any emotion.

"Casey, just ignore them-"

Casey cut him off. "Derek, please. I don't want to talk about it."

Derek sighed and left the table. When he returned to give Casey her glass, he saw Amy and Max both looking in Casey's direction. He then heard Amy say with a sneer, "Are you stalking us or something? Max chose me over you, all right? Leave us alone! It's bad enough you're always looking at us at school, now you're following us outside of school? You're so pathetic!"

Casey's eyes were obviously tearing up. She got up and went to walk towards the door. Derek quickly put down the glass of water and literally chased after Casey. He grabbed her arm and stopped her.

Casey looked up at Derek with pleading eyes. "Please. Derek, please. Let me go. I want to go. Derek, I NEED to go!"

Derek just looked at her for a second. He walked towards Max and Amy, pulling Casey along with him, though she was obviously resisting. "De-REK!" Casey cried.

Derek ignored her. "Ok, look here lady, Casey is NOT pathetic. What's pathetic is being so desperate that you're willing to be with a guy who already has a girl. What, no other guy can stand you? Or are you just so easy that other guys don't bother?" Amy gasped. Max turned to Derek.

"Watch what you say about my girl! What's your problem man? I don't understand why people think you're cool! You're so… lame! "

"Wow. That was a great insult. Did you come up with that on your own?"

Max gritted his teeth. "Why do you care? Everyone knows you hate Casey anyways."

"Derek, please. Let's go!" Casey whispered.

"No." Derek said. "You think I hate her? Then you are even more stupid than you look! And that is saying something! Casey McDonald is one of the people I care about the most. You mess with her, you mess with me! No one can hurt her and get away with it." Casey stopped trying to pull away from Derek and looked up at his face. Had she heard right? He cared about her? She was one of the people he cared most about? Since when?

"I don't think you're someone to talk Derek." Max sneered. "Everyone knows you're a player too. Since when do you preach about being faithful? As if cheating is something you'd never do!"

"Please. If I had one of the most beautiful, smartest, caring woman as my girlfriend, I would not cheat on her!" Derek said forcefully. Casey's eyes started filling with tears again. This time not because of hurtful words, but words that made her heart flutter.

Max snorted. "Are you implying that Casey is all that? Because if you are, you are wrong! Casey's not all that great; she seems much better from afar than up close. Not a very good girlfriend if you ask me. I mean, she's not even THAT pretty. Everyone knows she's picky with her boyfriends. I went out with her just to say I got to her, more than anything actually. "

Before Casey even registered those hateful words, Derek lunged forwards and punched Max straight in the face.

"Derek!" Casey gasped.

Amy let out a shrill scream. People started gathering around Derek and Max, who were now on the floor. Derek was on top of Max, repeatedly punching him in various parts of the body. The manager of Smelly Nellie finally came and broke up the crowd.

"What's going on here!" he yelled. "Derek! Get off right now!" he attempted to pull Derek off, but to no avail. Casey had just stood there dumbly for a few seconds before she finally came to her senses.

"Derek!" She cried. "Get off of him! Derek please!" She went up to him and gently grabbed hold of his arm. Derek suddenly stopped punching Max and got up.

"Derek! What is wrong with you! You are FIRED!" the manager yelled. "Now get out of here before I call the cops!"

"Derek, let's go." Casey whispered while pushing Derek out the door. When she glanced back, she saw Max with a bloody nose and scratches all over his body. Most of the crowd had disappeared. The manager was helping Max up while Amy crying like a banshee. When Casey shut the door behind her, she couldn't help but grin and think he finally got what he deserved.

(End Flashback)

After that incident, no one ever asked her personal questions anymore, in fear that her stepbrother would beat the living daylights out of them. In fact, it took 2 months for any guy to approach her.

Casey had been really affected by what Derek had said. His compliments and how he jumped to her defense gave her an over whelming happy feeling. She had been very confused and she finally realized that she had feelings for her stepbrother. She was hoping, waiting, for any sign that showed he cared for her the same way. But anything that he did could be seen two ways. One could see it as him returning her feelings, or that he was just showing some brotherly love. Casey did not want to make the mistake and misinterpret his actions and end up making a fool of herself and setting up a very awkward situation for them both. So Casey never made a move.

In the middle of her junior year, Noel, the boy she had co-starred with in her first school play, asked her out. Turned out he had a crush on her since the play they did together. Casey, hoping going out with Noel would make Derek jealous, said yes.

At first she was just using him. But after a while, she realized that she and Noel actually had a lot in common. She actually enjoyed his company. Before long, she started developing feelings for him. She actually saw him as her boyfriend, not just a tool to make Derek jealous.

Even though, she actually cared for Noel, she still had the overpowering feelings for Derek. At the end of her senior year, she realized it was time for change. Her relationship with Noel had run its course, and it was a good time to end it, especially since Noel was going to a college in the states. Casey told him that she still cared for him, but that she just wanted to be friends since they'd be starting college soon and long distance relationships don't work out. Noel agreed and they broke up amicably.

That summer seemed like the best time to let Derek know about her feelings. But all summer long, she was too afraid to let him know. There was at least a dozen times where she could've sworn that he was going to admit his feelings for her, but he never did. Before she knew it, they were both going off to college. Casey was dejected. She figured that if Derek truly had feelings for her, he would've told her sometime that summer. Since it never happened, she figured there was nothing to tell.

When Casey got to her school, she ran into Noel. Apparently, he decided that a college closer to home would be better. Casey believed it was fate. What were the odds that the pair of them would end up at the same college, walk down the same hall at the same time, both too absorbed in a book to notice where they're walking, and literally run into each other? Casey didn't think the odds were too high. So that's why she said yes when he asked her out.

They became official again, and their relationship was greater than before. Once again, Casey was truly happy with Noel. But there was still that piece of her heart that got tugged on every time she thought of Derek.

That's why when Noel asked her to marry him, she didn't answer. She knew that she had to have her answer. It was obvious that her feelings for Derek were not going away anytime soon. She had to figure it all out before she fully committed her life to Noel.

The night before she left to meet up with the family, she wrote Derek a letter that explained her feelings. She planned on giving it to him during the vacation, but again, she proved to be a total failure. She chickened out every time she thought of giving it him.

The night before everyone headed home, Casey heard a noise downstairs. When she went to go investigate what it was, she saw Derek. This was her chance. She had to find out how he felt about her. After talking a bit, she figured out a way for him to reveal his feelings. She told him that Noel purposed to her.

There were two options; one, he'd tell her that she should marry Noel, and it'd mean that he didn't see her as anything but his lame stepsister. She'd go home and marry Noel and live a life she always dreamed of. Then there was option number 2. The option she wished from the deepest depths of her heart that would come true. That Derek would tell Casey he wouldn't allow her to marry Noel because he loved her more than life itself. They would become a couple and get married. They would then live a life that was filled with so much love and joy that Casey never thought was possible. Of course, option number 2 had some kinks to work out before they live happily ever after, but she still wished for it, no matter what the obstacles were.

When Derek told her she should marry him, her world came crashing down. She had honestly not been expecting that. She had thought that Derek truly had feelings for her. But he insisted that she marry another man. Casey knew the answer to the question that had been haunting her for nearly a decade. He didn't love her.

When Derek asked her those questions about Noel, she had answered honestly. But what Derek didn't know was more to it than the answers she had given.

Yes, Noel made Casey happy, made her feel safe, made her laugh. They did have things in common, she did see herself with him in the future and she really did love him.

But what Derek didn't know was that there was a person who made her even happier, made her feel even safer, made her laugh harder. There was a person who she saw her lead a better life with, a person who she had more in common with, and a person who she loved much more than she loved Noel. That person was Derek Venturi. And he didn't feel the same way.

Once Casey entered the room she was sharing with Lizzie, she went digging into her purse. After looking through her purse for a few seconds, she found it. The letter.

She gave it a long hard look. She brought it to her heart before whispering into the night, "I guess it was never meant to be."

Trying to control her sobs as not to wake up Lizzie, Casey ripped the letter into hundreds of little pieces before opening the window and letting the pieces fly into the night.

Casey slowly crawled into bed. As her sobs subsided, darkness started to cloud her vision. She could've sworn she heard some shuffling of feet in front of the door. She then indistinctly heard the front door open and shut. She vaguely wondered if Derek was leaving for good again before sleep completely claimed her.

A/N: Awww… hey there peeps! Sorry this took forever to finish.

Ok, I know I said this was going to be shorter, but because I stuck that flashback in there, it got longer. This chapter was already insanely long (for my taste at least) so that's why it kinda rushed, especially at the end.

So again, please let me know if there's any typos, or if something was worded oddly or it doesn't make any sense. I think there were a few of those in here….

I WILL be writing a sequel. Just because I love writing so much, and because I know you all want a Dasey ending (including me)!

Thanks to everyone who reviewed! Now that you've read this chapter, review again! Lol. Anyways, hope you enjoyed! Look out for my sequel! (though it might take a while….)