Derek stared at the wall separating his room from Casey's and wished with every fibre of his being that he could read minds. This situation with Casey had spun so far out of control that there weren't words for it anymore. If he were to look at it logically, nothing serious had happened, only a few close calls and charged moments. But there was zero room for logic at this point because he was starting to think he felt something for her. An attraction to her was one thing, and it was easy to explain, but it was moments like that morning when they were hanging out watching movies and she'd had her feet on him that he'd liked. Moments like when he was talking to Nora and Casey'd leaned up against him, and yeah, he'd gotten a little thrill out of it, but it was just being close to her that had got to him the most. He could think of only one other person in his life that had affected him like that, and he'd nearly moved across the country for her.

Derek pulled a pillow over his face and debated if smothering himself and just ending it all would be the better option.

The worst part of it was that he wasn't sure that Casey wasn't just playing him. She'd been a lot more proactive in tempting him in this game than vice versa, so maybe this was just another tactic? He sighed and threw the pillow aside. No, probably not. He was reasonably sure that the way she'd been acting lately wasn't a part of the game, especially after what Danielle had told him, and how Casey had acted last night in the bar. He just wasn't confident enough to do something about it. No, the best thing to do was to ignore whatever ludicrous feelings he thought he had and pretend everything was normal.

Yeah, good luck with that, his inner voice taunted.

Casey was already dressed and eating breakfast when she heard Derek moving around upstairs, presumably going in for a shower. She hadn't slept much the night before and was up at the crack of dawn, early enough to see Lisa off for her morning run. She'd also finished packing and had her bags ready to be loaded into the car despite the fact they weren't leaving until the next morning. And, as usual, she was trying and failing to not think about Derek and their situation. She'd nearly come to accept that she wanted him, game or no game, but the logical part of her mind was staunchly refusing to accept it was anything more than physical. Because there was absolutely no way she could possibly feel anything else for the smug, arrogant, man-slut she called a step-brother.

Nope. No way.


She sighed and dumped her dishes in the sink before trudging up the stairs. It was sheer bad luck that her timing coincided with Derek coming out of the bathroom, shirtless and rubbing his damp hair with a towel. He caught sight of her and after a second's hesitation smirked and flexed his muscles.

"Morning Princess…Like what you see?"

Casey bit back a smile and couldn't help but give him an exaggerated once-over, like he'd done to her the other day after the underwear incident. Hockey had been very kind to him, she had to admit. He'd filled out quite a bit over the years and it struck her like a bat to the head that Derek wasn't a boy anymore, he was a man. She opened her mouth to give some smart, sarcastic reply, but instead said: "What if I do?"

She wasn't sure who was more surprised by that comment between the two of them. Sure, she'd nearly talked herself into taking action last night, but realistically that was the last thing she would have expected to come out of her mouth under any circumstance. And in most circumstances Derek would have smirked and fired back some lame comment about how irresistible he was, but now he looked more serious than she'd ever seen him. He took half a step toward her and her breath caught in her throat. She pressed her hand to his chest to stop him, afraid of him coming any closer. He came closer anyway, and she didn't move her hand. In fact she was having a hard damn time stopping her fingers from roaming across the broad expanse of his chest.

He reached up to comb back a few strands of her hair and she couldn't help but lean into his hand just a little. "Casey," he said quietly. "What are we doing?" She was afraid to meet his eyes but forced herself to look up. "I don't know, Derek." Her heart was pumping like a jackhammer, and so was his by the feel of it under her hand. "I know what we should be doing," he said quietly. "But I also know what I want to do." Then he brushed his thumb over her lips and she nearly lost it.

"And what's that?" she murmured, too stunned to move. He said nothing but continued to trace her mouth with this thumb. She could feel the tension rolling off of him and realized they had officially crossed that line, the one she'd refused to acknowledge the existence of until this game had started but was now willing to admit might have been there for a long time before. As if it had a mind of its own, her hand moved from his chest and trailed down his abdomen to hook a finger in the waistband of his pants. She tugged ever so slightly and brought him another step closer. They were thigh to thigh now, chest to chest. It was the ultimate game of chicken and neither one wanted to give in first. Good god, she had never wanted anything more in her life than for him to kiss her in that moment. But then the door banged open at the bottom of the stairs and Lisa came stomping in, and Casey nearly wept with relief (frustration?) as the moment was broken. Derek dropped his hand and stepped back, his dark eyes never leaving hers. She wordlessly turned and went into her room, closing the door soundly behind her.

Derek stared at Casey's bedroom door for a moment as the need and the want raged in him. What the fuck had just happened?

"Morning!" Lisa said cheerfully as she came up the steps. He shot her a look so full of loathing that she actually recoiled. "Jesus, what crawled up your ass?" He could have happily throttled her right then – if not for her coming in and interrupting the moment, he and Casey would be –

He cut the thought off and stormed into his own room, slamming the door behind him. He wanted to yell or to hit something, or… no, what he really wanted to was to go into Casey's room and finish what they'd started out in the hall. But of course he couldn't. He threw himself onto his bed, and his fingers itched to reach for his phone to call somebody, anybody who could set him straight. He was not allowed to want his step-sister so badly, especially one he'd considered his greatest foe for so many years. He considered calling Sam but the thought of trying to get the words out made his throat close up. Sam wouldn't really understand…no one would. He tried to distract himself with video games, then he completely cleaned his room, shoveled half the neighbourhood, and finally got around to packing. It was as he was unceremoniously shoving things into his bag that there was a tentative knock on his door. He glanced over and his jaw tightened. "Hey."

Casey didn't make a move to actually cross the threshold but stood in the frame with her arms crossed so tightly her fingers probably met on the other side. "Hey. Um." She took a deep breath and focused on the mess in his suitcase. "We need to talk." Four of the most hated words in the English language, yet all he could think was: No shit, Sherlock. Derek Venturi was not a talker, especially when it came to feelings, but there was no getting around it this time."Yep."

She inched forward a couple of steps and cast a quick glance across the hall at Lisa's closed door. The indecision was written all over her face but she pushed his door shut. "So?" he said, and she finally looked at him. "Why do I have to start?"

He shrugged petulantly. "You came to me, remember?"

"Yeah, well, I guess I'm just braver than you." It might have been considered a dig once upon a time, but in this situation he took the comment at face value and sighed. "Yeah, I guess you are." That seemed to boost her confidence some and she came over to the bed and started taking the mountain of clothes out of his bag to fold them. "This has to stop," she said finally, after she'd made a neat pile out of his shirts. He'd been expecting it, of course, but his heart still constricted and he couldn't help but be difficult about it. "What does, exactly?"

"Oh, don't even," she huffed, but waved a finger between the two of them. "This. The game. Us. You know what I'm talking about." He wanted to feign ignorance or tell her she was crazy, but instead his shoulders sagged and he gave a jerky nod. "Yeah, no kidding." There, he'd acknowledged it, and his saying it out loud seemed to burst whatever dam Casey had set up to hold herself together.

"I mean, it's crazy, right? I don't even understand how it happened!"

The memory of that night in the kitchen when he'd wanted to see that tattoo of hers flashed in his mind. That was the start of the attraction for him, but he didn't tell her that. "It must just be because of the bet, you know?" he said quietly. He desperately wanted to believe that, but deep down he knew there was more to it. Just because a girl was hot did not mean he developed feelings for her. She hesitated, then shrugged. "I guess, which is why I'm calling it off. I just…things need to be normal again, you know?" He opened his mouth to say, yes, you're right, I completely agree, but instead he heard himself say: "how can they?"

"What?" she said warily. He started pacing. "Casey, how can things possibly go back to normal after this? Do you know how many times over the last few weeks that I've wanted you? I can't erase that."

"I know!" she said angrily. "I know that, okay? I can't get you out of my head, Derek, and it's driving me nuts! That's not going to stop just because the stupid game does!" Derek stopped to stare at her. She looked furious and embarrassed and ready to bolt. Finally he threw up his hands. "Oh, fuck it," he said, and kissed her.

A huge part of him hoped that he would feel nothing, that by kissing her he could get her out of his system. He was sorely disappointed. He felt…well, there weren't words to describe it, and when Casey wrapped her arms around his neck and deepened the kiss, heat coursed through him so fast he thought he would burst. He wanted to lift her up and have her legs wrap around his waist and to take her to bed, and because of that he very reluctantly put his hands on her hips and pulled back. She was pink-cheeked and breathing heavily and stared up at him, clearly shocked. "I guess it's a draw?" she said finally. "Guess so," he replied lamely. She fumbled with the door and left without another word, and he sank down onto his bed. Oh, this was bad.