Wow what an episode! George and Lexie, Izzie and Alex and of course Meredith and McDreamy!

Derek: Hey Rose! Rose: You know my name! Derek: I had to ask around but now I know. Rose: Oh, good for you. Good night. Derek: Hang on, I should have recognized you form the OR today. We worked together for three hours. Rose: I've worked on 36 of your surgeries and today was the first time we made eye contact. Like I said, a hospital is no better than high school. Good night, Dr. Shepherd.

Before we were doctors, we were med students, which meant we spent a lot of time studying chemistry. Organic chemistry, biochemistry, we learned it all. But when you are talking about human chemistry only one thing matters: either you've got it or you don't. (Meredith narrating).

Most Grey's Anatomy die-hards love Izzie Stevens and George O'Malley together, thinking they are "cute" and so perfectly matched, and then there are those who just don't...

There's a new head of heart surgery at Seattle Grace and she's got some of the staff's blood pumping...and she's also about to catch the heart of one of Seattle Grey's biggest heart-throbs. Who could it be?

Callie Torres is mad, she's mad as hell about the enforced breakdown of her marriage. She loved being married to George, and although she had her doubts about the validity of his friendship with Izzie, she put all her suspicions aside for the sake of her marriage, and now she finds out she was right all along.

Izzie gets the answer she has been waiting for as George confesses his love for her. But when push comes to shove, will George have the courage to tell Callie he's been having an affair with Izzie and end their marriage once and for all?

Will Derek be able to walk away from his relationship with Meredith just like Burke walked away from Christina when he realised he was getting less than he deserved?

On the first day back from her honeymoon with Cristina, Meredith comes face to face with a half-sister she never knew existed, who has joined the group of first year interns at Seattle Grace. On top of that her half-sister is the "the girl from the bar" that Derek was referring to. With Meredith's emotional withdrawal from their relationship could Leslie Grey be the next intern to sleep with an attending?

Another season of Grey's has drawn to a close and a new waiting period begins. While it appears the question marks hanging over some relationships have been answered, some questions still remain...