Grey's Anatomy did not kill off Alex Karev.

Based on the show's history of writing off veteran characters, this came as a big surprise on Thursday night when the series revealed the fate of Alex Chambers' beloved doctor.

And yet... it wasn't even close to the biggest surprise of the evening.

About two months after Chambers announced his departure from the show, Grey's Anatomy aired an installment that informed viewers he had left Seattle...

... FOR IZZIE!

In four separate letters to wife Jo, Meredith Grey (Ellen Pompeo), Miranda Bailey (Chandra Wilson) and Richard Webber (James Pickens Jr.), Karev explained — amid flashbacks from across the past 16 seasons — the reason for his sudden exit:

He’s moved to Kansas! To be with his ex-wife, Izzie Stevens! And their 5-year-old twins.

Wait... what?!?!?!?!?

First in his letter to Meredith, Alex thanked his “person” for all she’s done for him, adding in shocking detail:

Mer, this is not the way I wanted to do this, but you know me.

Any chance to take the easy way out. You know as well as I do, you’d yell or give me guilt or crap or whatever you do that seems to always set me straight. You were always the one to set me straight.

When that didn’t work you’d flop in my bed and say the one perfect thing that would make sense. The thing is, I can’t come back. I can’t face you. I deserve the guilt and to be called an ass.

I don’t want to be set straight. I don’t want you to say the right thing. Because the one perfect thing isn’t in Seattle. Not anymore. I swear it’s not about you or work or Jo, it’s about me.

I left and I’m with Izzie.

Izzie, of course, was written off the show years ago after Heigl expressed dissatisfaction with how her character was being portrayed.

She left under not-so-great terms and the series has rarely mentioned her ever since.

Izzie and Karev, however, were one of the drama's first great couples.

On the episode, Alex explained that he had called Izzie during Meredith’s insurance fraud trial to not only get a letter in support of Grey but to “hear her voice.”

“She said, ‘Yeah I have kids. Twins.’ It turns out they’re my kids, Mer. Izzie and my kids.”

Izzie dealt with Stage 4 metastatic melanoma in season 5.

During her chemotherapy, Stevens and Karev made embryos and got married.

However, after her tumor was successfully removed in season 6, Izzie peaced out Seattle -- while Karev stayed behind.

As for Jo?

“You deserve more than a letter,” wrote Karev, adding:

This right here, this cowardness, it’s officially the worst thing I’ve ever done. It’s about me, it’s not about you. You deserve so much better than this.

I love you, Jo. I love that you are brilliant and brave and no matter what you go through you never let it hold you back. It makes you stronger, kinder. You made me kinder. You love me for exactly for who I was and I loved you. I love you.

Maybe it’s not fair to say that but it’s true. But this is also true. I’m in love with Izzie.

He added:

I imagined this whole life for her where she was happy and had a bunch of kids. I never imagined me in that picture but suddenly I am … There was a part of me that always wondered, always wanted to know, always felt like we left thing unresolved …

I reached out to her and we started talking and it scared the crap out of me.

He went on to say that he simply couldn't leave once he learned about his children.

Alex then told Jo he had signed divorce papers and left her his share in Grey Sloan Memorial.

“You deserve everything good in this life,” he told Jo. “I hope you find somebody so much better than me. Thank you I’m sorry.”

Finally, this is what Karev wrote to Baily:

You were mean and impatient and knew everything and liked everyone else but me, even when you pretended you didn’t.

Or you were convinced they had ‘it,’ that something that would make them great some day.

Hell, you named your kid after O’Malley and Mer named harked after you and you, you just seemed like all my other teachers before you who took one look at me, decided I was garbage and that was all I’d ever be.

But here’s the thing, unlike everyone else, you let me grow the hell up. You gave me crap when I deserved it. you pushed my buttons and my limits when I needed it.

Yeah it’s a teaching hospital and all that. But you did more than that. And you know it.

And sure it’d be pretty great if I just stayed there forever and repaid you for everything you did for me, but you and I both know I can’t. I never could. You helped me grow the hell up and you took a bullet out of my stomach.

You protected Jo from herself and if I started the whole list of everything I learned from you, I would never stop writing. Just know this, it took me a long time to say it, but I’m a good Peds surgeon. I’m an OK guy. I’m still trying. But I’m a really good damn surgeon …

I know who I am. I became the guy you trusted at the hospital to keep your secrets and now, I’m a surgeon. A friend. A father of two incredible kids with Izzie Stevens …

I love you Dr. Bailey.

Wow, right?

Did anyone see this coming?!?

"There’s no good time to say goodbye to a show and character that’s defined so much of my life for the past 15 years,” Chambers said in a statement lat month, concluding:

“For some time now, however, I have hoped to diversify my acting roles and career choices.

"And, as I turn 50 and am blessed with my remarkable, supportive wife and five wonderful children, now is that time."