If our experiences in life were physical scars, our beloved interns would be covered with them. But even if they're only scarred in a figurative sense, their outlooks on life continue to transform before our eyes.

Chief Webber brings a new doctor - and potential chief successor - to the hospital by the name of Colin Marlow. He's a renowned surgeon (obviously, if he's going to compete for Richard's job) but there's something a little more significant about him than that. He's one of Cristina Yang’s former professors. And her ex-lover.

Any chance she had of concealing this evaporates when he gives her a hug (and more) as he's introduced to the rest of our group.

In typical fashion, Yang tries to blow the whole thing off with Burke, but during a surgery, Marlow nonchalantly drops this piece of knowledge - he and Cristina not only dated for three years, but he proposed to her more than once, only to be rebuffed because she didn’t believe in marriage.

When Preston confronts her about this, Cristina tells him pretty matter-of-factly that she doesn’t really care about the whole marriage thing but that she’s going through with it mostly to make him happy. It hurts him to hear this (as you might imagine). Burke worries she’ll just decide to end their relationship in similar fashion. After another argument, Cristina winds up spending the night at Meredith’s house.

If you thought that was weird, we're just getting started. Izzie works with an elderly man who was shot during the Korean War. By a guy on his side. On purpose.

The doctors must operate to remove a bullet that's been lodged in the man for nearly half a century. When they present it to him after the operation, he breaks down, decimated by its tiny size. He expected it to be bigger, more befitting of the burden he's carried all his life. He urges Izzie not to let anything so awful happen to her that her good soul is changed.

By now, the attendings are all acutely aware that this Colin Marlow guy is a frontrunner for chief - and waste no time in kissing up to him... and accusing each other of kissing up to him and neglecting what's important. Richard, of course, is subjected to their bickering yet again, and thinks he's probably pretty smart for bringing in some new blood.

Despite having taken up residence in Meredith's place, Alex spends most of his spare time with Jane Doe, who undergoes surgery on her eye. There are complications with the baby, but Addison handles them accordingly. At the end, Alex implies he has a hot date during a run-in with Izzie, when he's really just going to see Jane D. She's still badly hurt, but it's clear from the way he acts that Dr. Karev feels a real connection to her.

Emotions run high as Derek treats an old friend, Helen, for a brain tumor. She's losing the will to go on after so many surgeries, but McDreamy tries to convince her to have hope and be willing to try again if this time isn’t successful, but she’s made her decision: this surgery is her last.

Despite heart complications during the surgery, Derek guides her through it, removing the tumor for good. Finally, she can live her life.

Now for the most scarred Seattle Grace intern at all. First of all, she's determined to change her outlook on life after her near-death experience. But will she be able to? Susan Grey convinces her to have dinner with her and Thatcher. Meredith agrees. She and Derek have them over for dinner.

It's awkward. Very awkward.

Just when we think Meredith’s about to lose it, though, Izzie blows a fuse and Thatcher heads down to the basement to fix it. He did own that house at one point, after all. Thatcher collect his thoughts in the laundry room to stall, while Meredith and her stepmother manage to have an actual talk. In the basement, Derek confides in Thatcher that Meredith is a handful, but getting close to her in spite of that is worth it.

Finally, George learns a secret about Callie: Let's just say that Izzie isn't the only heiress in town.

That's right, Callie is from a rich family. George, of course, tells just about everybody. Izzie later makes a comment about Callie’s cash and Dr. Torres is livid. Callie tells George that she thinks he has feelings for Izzie and vice versa. Rather than denying it, however, George replies that there's no way a hot blonde like that would be into him.

Not good.

Callie thus throws George out and he goes to Meredith’s house to blow off steam. He and Izzie get drunk off Knob Creek and sit around laughing and talking about the mess their lives have become. George tells Izzie what Callie said and she laughs so hard she gets tears in her eyes.

That's when things change. He has his hand on the back of her head and they stop laughing, just gazing into each other sites.

The next thing we know, it’s morning, George is in Izzie’s bed and they’re naked. Izzie realizes what happened the night and the look on her face is something akin to abject terror.