‘Grey’s Anatomy’ Executive Producer: “A Bomb Has Hit” Meredith, Callie and Amelia

Exec producer Debbie Allen talks with THR about how everyone will respond to Callie's new girlfriend — also known as the doctor who killed Derek — arriving at the hospital. Courtesy of ABC

Exec producer Debbie Allen talks with THR about how everyone will respond to Callie's new girlfriend — also known as the doctor who killed Derek — arriving at the hospital.

[Warning: This story contains spoilers from Grey's Anatomy's "Guess Who's Coming to Dinner" episode.]

Just when everyone had seemingly moved on from Derek's (Patrick Dempsey) death, Callie's new girlfriend Penny (Samantha Sloyan) arrived at Meredith's dinner party and brought the ghost of McDreamy with her.

During Thursday's episode, Meredith (Ellen Pompeo), Amelia (Caterina Scorsone) and pretty much all the major players at Grey Sloan Memorial were blindsided during a dinner party when Meredith revealed that Callie's (Sara Ramirez) new girlfriend is the doctor who failed to stand up to her superiors and order the test that could have saved Derek's life.

Worse: Callie had no idea and is now caught in the middle between dear friend Meredith and her new girlfriend — who she's been raving about pretty much since season twelve started.

Further complicating the matter, it puts a rift between Meredith and Amelia, who is upset that her sister-in-law allowed her to buddy up to Penny.

THR caught up with Grey's Anatomy exec producer Debbie Allen, who also directed this episode, to get the scoop on what to expect after the most uncomfortable dinner party, ever.

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Was it always the plan to have Penny return? Why bring her back now?

She was a doctor who needed to be guided. When Derek died, Meredith tried to teach her something at the time to make her stronger so she wouldn’t make that mistake again. The whole point was that Derek could have possibly survived if she had done that other test. She didn’t push hard enough.

Why did Penny choose this hospital? Did she know that she was going to be coming to this hospital where Meredith worked and where Derek spent his entire career?

I don’t know if that was her intent. Her hospital went under; it wasn't a good one. Grey Sloan is a great teaching hospital, which is why we have so many great interns and residents. I think Penny is going to become a better doctor and this is the opportunity that came to her. It’s such a big hospital; I don’t know if she ever thought she would see Meredith but I don’t know if she came looking for Meredith. She got in a relationship with Callie, that’s how she got over here. Their relationship is very loving and warm, and we’ve heard about it a lot.

How long might Penny be sticking around?

There’s a lot coming that is so interesting and very new to Grey’s — just in terms of relationships and chemistry. Penny is going to be around a bit.

What’s the story you’re looking to tell with this arc and bringing Penny back? It creates a lot of conflict for a lot of people.

It’s really about personal growth and expression. In tonight's episode, Meredith says things about Derek’s death that she has never said before. I think Meredith is going to learn a lot through this story. But what I take away from it is Meredith’s growth as a human being and getting to a place of real forgiveness. It’s a big thing. There are a lot of relationships on the rocks right now: Jackson and April, Stephanie and Jo. Arizona doesn’t quite have a relationship. This is a lot about where people are going. Where are Amelia and Owen going?

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How will Penny’s arrival impact Meredith and Amelia? That’s the biggest relationship that’s on the rocks right now.

Absolutely. It is just amazing what happens; the gloves really come off.

We’ve seen Meredith wasn't completely upfront when Penny first arrived at dinner — will that be something that Amelia holds against her, especially after being so friendly?

Meredith can’t deal with it and is just trying to get through the night. You see what happens in this episode: Meredith says, "Get her out of my room before I kill her!" She is talking about Amelia, not about Penny. Amelia is so caught up in how she feels, she’s not even thinking about what Meredith has gone through. It’s family time. The people closest to you are the ones who can hurt you, misunderstand you or make it difficult. The people you don’t care about, you can just walk away from it.

Where do they go from here?

It’s going to be a real challenge for them. They don't end this episode on good terms. Penny’s going to be at the hospital. What is that going to be like? Amelia is just done with Penny — and she was so nice to her without knowing who she was — but now she knows something else. It’s a real reversal of fortune for everyone. Talk about being blindsided. Meredith and Amelia are blindsided. Everyone else’s problems kind of go away. When Meredith says who Penny really is and walks away, it shuts everything down. Everyone’s problems become smaller. It’s like a bomb has hit. Wounds, missing limbs, broken hearts and spirits … all pale in comparison. 

We know at the end of the episode, Meredith says, "Don’t get reassigned, come in but don’t be late." How will Meredith and Amelia juggle with having Penny at the hospital? How will their reactions to her differ?

It’s going to be really tough. Amelia doesn’t want to see her.

How will Penny come between Callie and Meredith’s friendship?

Well first of all you have to get Callie to just figure out what’s happening between her and Penny. At the end of the episode, Callie doesn’t even give her the address to where she is. Callie doesn’t know how to react. Callie feels that maybe Penny should have told her more.

Does that threaten her relationship with Penny?

Absolutely.

Will Callie be apologetic to Meredith? What can you say about their dynamic moving forward?

Their dynamic is going to be really intense. Callie has to figure out what her relationship with Penny is because she was really blindsided about her role in Derek's death. It's not like Penny could have told her. What could she really do? This was beyond her.

What about Arizona? Will Arizona lean on Callie? Will it prompt Arizona to start dating?

Arizona will just find her own space. Callie has expressed how she feels about this person. That it’s very cute and they complete each other’s sentences. Arizona was a little put off by that.

What did you think of the episode? Sound off in the comments, below. Grey's Anatomy airs Thursdays at 8 p.m. on ABC.

Grey's Anatomy

Lesley Goldberg