Disclaimer: I own nothing.

Yesterday my stepsister went on her first date since she moved in with me. And when she told me about it I was happy for her. Really I was. The way her last relationship ended was, well, horrible, so it was a big step for her.

She was so excited about the whole thing too. Excited and nervous. She must have spent the entire afternoon just trying on clothes. And doing her hair. And generally fussy about everything in a way that you just can't help smiling at. It was good to see her like that again.

And, of course, the outfit she settled on was perfect. She looked beautiful. There was no other word for it. Not that she realized it. That's another thing that's funny about her. She's not really aware of how pretty she actually is.

When the guy arrived at our door she was all smiles. Glowing really. It was a blind date so she'd never met him before. He was just her type too—tall, muscular, well-dressed. I talked him for a few minutes and he seemed like an okay guy. Likeable.

But then he helped her put on her coat. His hand lingered on her arm a certain way and I saw her eyes dance flirtatiously. And it hit me that this guy could become her new boyfriend. Somebody that she could end up with . . . And at that moment I felt a sharp pain. As if I had suddenly been punched in the stomach. My blood ran cold and I said goodbye to her and wished her luck as if in a daze.

When the door closed and the sound of her heels in the hallway faded, all the heat rushed back into my body. I felt . . . angry. Thinking about her out with him. Thinking about them talking and laughing and having fun. It was like I couldn't focus on anything else. All I could do was sit there. Sit there, think of her, and burn.

Although that evening felt like an eternity, she actually got back pretty early. Apparently it hadn't gone that well. He was not her type after all. She laughed as she told me about their dinner conversation and how he'd been totally completely wrong for her. She said that she was glad that she was getting out there again though and headed to sleep smiling.

But I couldn't sleep. In fact, I don't think I slept at all last night. Because when she came home it had been, well, such a relief. And when she mentioned getting out there again it was like my world came crashing down. Because I realized something.

I realized that I was painfully, horribly, miserably in love with my sister. And if she ever found out she would be horrified. And that . . . that's something I couldn't take.

"I thought that you said she was your stepsister."

Just because we're not related by blood doesn't mean that she's any less my sister. Our family thinks of it that way, she thinks of it that way, I think of it that way . . . Well, almost.

"So from the day your parents got married she automatically became your sister?"

No, of course not. I know it doesn't work that way—I'm not being naïve about this. When she first moved in I'll admit I didn't see her that way. She was hot; we were not really related; I was attracted to her. But in time I came to see her that way. By the time I moved to New York I almost thought of her has my own flesh and blood.

So feeling this way, thinking about her like, wishing for something that can never happen—it's sick. The whole thing is sick.

"Sick?"

Well, it's incest! I have an incestuous desire for my sister!

"Calm down, Mr. Venturi. There's no need to shout."

I'm sorry. It's just that she's good and light and pure. And thinking about her that way, well, I'm . . . It would shock her. And I could never drag her down with me by telling her.

"That's interesting that you say that."

Yeah, the whole thing is scintillating. You people must really get off when someone openly admits that they're fantasizing about a family member. But just tell me already. Can you help me?

"I'm sorry, Mr. Venturi, but our fifty minutes are up."

Author's Note: This one is going to be darker than my previous stories. It's written in response to the claim that Derek and Casey seemed more like brother and sister in Season 3 (which I don't necessarily agree with) and the possibility that the show might end on a non-Dasey note. I know where I'm going with it, but it definitely won't be updated for at least a couple weeks.