Ellen Pompeo, Patrcik Dempsey Ellen Pompeo, Patrcik Dempsey

After two months off the air and the sad death of Teddy's husband, the spring episodes of Grey's Anatomy promise happier times, especially now that Meredith (Ellen Pompeo) and Derek (Patrick Dempsey) finally got custody of baby Zola. We'll even see a not "dark and twisty" Meredith in the special alternate-reality episode. But it's not all bright and shiny: TVGuide.com sat down with executive producer Shonda Rhimes, who told us that Cristina (Sandra Oh), for one, is heading toward dark times. And what's this about George and Izzie returning?

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ABC President Paul Lee announced Tuesday that he has high hopes for Grey's to return for next season. Are you ready to tackle that?
Shonda Rhimes: I feel like we were told that is what's happening. So, we're just making the plans the way we always make the plans. I have a full plan for what's going to happen next season. I have to say a month-and-a-half ago I didn't have a full plan. But one day, I woke up and I did.

The obvious question is if Pompeo decides not to renew her contract, is Lexie (Chyler Leigh) being prepped to be the Grey of Grey's Anatomy?
No. I mean I love the character of Lexi. I think Chyler is amazing. That was never really the vision of the show, like we were seeking a replacement. I wouldn't assume that at all.

Now that Meredith and Derek have Zola back, how will that change the dynamic of their marriage?
They're having so much fun with Zola that it's been amazing to watch. I also love, story-wise and character-wise, the evolution of Meredith's character, this woman who, I remember saying in a bunch of interviews, she will never have kids. Then, really using the shooting to get her to a place where she would think that maybe she would want to have kids, and to now see her as a mother is really beautiful.

I didn't feel like their marriage was messed up. She just felt like if they couldn't get their baby back, it was going to be a problem, but there's a lot of joy there, which is really fun to see for the two of them. They're having a lot of fun together.

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What will we see for Mark (Eric Dane) and Lexie, who clearly still have feelings for each other, which is made especially difficult now that we know Lexie doesn't hate Mark's new girlfriend?
I don't think that's going to change her being able to overcome her feelings though. Mark and Lexie, I love them together. We have heated, heated arguments in the writers' room about the two of them. Some people feel like they shouldn't be together at all, he's too old for her, he's got a baby. I feel like she's got some growing up to do, as does he and maybe they're going to get there.

Following the death of Henry, it seems like Cristina and Owen (Kevin McKidd) are about to hit a rough patch. What can you tease?
The explosion is coming. I think it's going to affect every corner of their lives. Some of the performances that Sandra and Kevin are turning in are, like, people are crying while watching the dailies. It's unbelievably good what they're doing.

Fans are really invested in the Cristina-Owen relationship and would be, ahem, very outspoken should anything happen to them.
I think everyone's really dedicated to them as a couple. I'm not going to say whether or not they're going to break up or not because, honestly, that's kind of not the point in this. But I feel like they're two people who really want to be together, who are fighting to make it work. What that's going to mean is it's going to be fairly painful, even if they make it work. It's going to be a painful journey.

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Turning to the alternate-reality episode, we know that Derek is still married to Addison (Kate Walsh), but who is Meredith with?
There are some very surprising things that happen in the alternate-reality episode. I know that fans have been going crazy with their worries and their fears. It's an alternate reality, which means it doesn't exist. Really, the premise is what would have happened if Meredith's mother had never had Alzheimer's, if Meredith had been raised as a bright and shiny person. So, bright-and-shiny Meredith makes a lot of things in the world very different. I think it's really surprising when you discover what she's been doing with her time and the kind of person she's become.

What about Cristina in the alt-reality?
It's the idea that without Meredith there to be her ally in anything, and if Meredith hadn't been there to cut her out of that wedding dress, who would Christina have been? She's just a fundamentally different person and, I think, a lonely one. 

And Bailey (Chandra Wilson)?
Without Richard to spend the time mentoring her, Mandy Bailey might have stayed Mandy Bailey and never gotten to be the Nazi.

Now that we know Callie and Owen are together in the alternate-reality episode, what will we see for them?
Callie being with Owen is the largest mistake of both of their lives. It's very funny because they so have no business being together. She's so pining for this peds surgeon and she doesn't know why. It's because she never had Mark Sloan there and Erica Hahn (Brooke Smith) never came, because [Callie] was the heart surgeon, so she never had her first experience with a woman.  It's really charming and beautiful. It's more about the fact that they're with the wrong people than it is about them being together. 

Will there be a mention of George and/or Izzie in the episode?
You understand where they went in this new world.

Grey's Anatomy airs Thursdays at 9/8c on ABC.