(Derek walks out of the shower, and screams upon seeing a woman on his bed.)
Derek: Oh! Oh, God!
Nancy: Well hey there stranger.
Derek: Nancy, you don't call first? (Meredith enters.)
Meredith: Hey, I...
Derek: Meredith... Meredith. Wait let me explain! Meredith!
Nancy: I take it that was the slutty intern you cheated on Addison with?
Derek: She's not slutty. What are you doing here?
Nancy: You bailed on Thanksgiving, then Christmas, you're living in a trailer, and you're getting a divorce, and then there's the slutty intern.
Derek: I really don't like you.
Nancy: You love me.

Derek: Dr. Stevens, Meredith, this is my sister Nancy.
Meredith: Sister? You're one of Derek's sisters?
Nancy: Well I knew you didn't think I was the wife, seeing as how you already ran her off.
Derek: Nancy is visiting from Connecticut. She's on her way home... now. Straight back home.
Meredith: Well it was nice to meet you.
Nancy: Okay...
Izzie: McDreamy's sister is McBitchy...

Meredith: So your sister really doesn't like me, huh?
Derek: Sorry. It's just... she's from the East Coast.
Meredith: Well I...
Derek: You know, I should have called.
Meredith: But you didn't.
Derek: I want us to work it's just... It's complicated. I think I need a little time to...
Meredith: Take some space.
Derek: Yeah. To clear my head.
Meredith: Yeah. Okay. Okay.
Derek: Okay.

To make it - really make it - as a surgeon, it takes major commitment. We have to be willing to pick up that scalpel and make a cut that may or may not do more damage than good. It's all about being committed, because if we're not? We have no business picking up that scalpel in the first place.

There are times when even the best of us have trouble with commitment, and we may be surprised at the commitments we're willing to let slip out of our grasp. Commitments are complicated. We may surprise ourselves by the commitments we're willing to make, true commitment, takes effort, and sacrifice. Which is why sometimes, we have to learn the hard way, to choose our commitments very carefully.