'Grey's Anatomy' Boss on Making TV History, Going All In With MerLuca and That Unexpected Arrival (Exclusive)

Warning: Spoiler alert! Do not proceed if you have not watched Thursday's 332nd episode of Grey's Anatomy, which officially makes it the longest-running primetime medical drama, surpassing ER.

Grey's Anatomy became the longest-running primetime TV medical drama Thursday by celebrating with a party, both on and off screen.

Abandoning tradition, ABC's crown jewel marked its milestone 332nd hour -- officially surpassing ER for the honor -- with a get-together that brought together the current ensemble, led by OGs Ellen Pompeo, Justin Chambers, Chandra Wilson and James Pickens Jr., to commemorate Catherine's (Debbie Allen) new lease on life following her successful cancer surgery. Unlike the majority (if not all) of Grey's' previous episodes, this one didn't feature any medicine or medical case, a decision showrunner Krista Vernoff, whose history with the show dates back to the groundbreaking 2005 pilot, said was intentional.

"It's pretty extraordinary, and a little surreal. ER is such a television legacy, and was such an extraordinary program. If ER didn't exist, Grey's wouldn't exist. So, we owe a tremendous debt of gratitude to ER, and to [executive producer] John Wells, and we are so grateful," Vernoff, who spent five seasons working alongside Wells on Shameless, told ET on Thursday of Grey's making history. "This is exciting and monumental and a little crazy, and we're all just sort of walking around here looking at each other like, 'What?'" (George Clooney, who played pediatrician Doug Ross on ER for the first five seasons, joked in February, "That's got to stop. We gotta go back and do more!")

And unlike the Grey's landmark 300th episode in its 14th season, which paid tributes to past cast members who have since departed, like Sandra Oh, T.R. Knight and Patrick Dempsey, hour 332 looked ahead at what's still to come for the doctors of Grey Sloan Memorial Hospital. Because, as Vernoff said, "To celebrate how far we've come, and how far we have yet to go."

Following Thursday's historic Grey's TV moment, Vernoff jumped on the phone with ET to reflect on the lasting legacy of the ABC series and looks ahead at what's still to come, including Meredith and DeLuca's full-fledged romance, the unexpected arrival of DeLuca's father and what's next.

ET: Congratulations on making TV history! How did ER shape Grey's Anatomy into what it's become?

Krista Vernoff: ER broke the mold for medical shows, and it was incredible, and it was dramatic, and it was just groundbreaking television for its time. And when we were in the writers' room in the early years of Grey's Anatomy, our conversations were often, how do we do it differently than ER? Like, we didn't want to be an ER copycat. How do we be in the hospital world and do it differently than ER? In the early years of the show we rarely brought in patients through the emergency room. They usually came in through surgical rounds.

We leaned, tonally, into romantic comedy, which I think was a part of [creator] Shonda [Rhimes]' pitch from the very beginning. As I recall, when she pitched the show, she said, "We have the drama and excitement of ER, but a tone that's all our own, with romance and humor in equal parts." We always, in television, build on each other's legacies. There was MASH, and then there was China Beach, and there were multiple shows in between, and there was ER, which really broke new ground. And Grey's Anatomy is... We all stand on each other's shoulders.

In approaching this particular episode, what did you want to accomplish or achieve with this hour that differentiated it from a typical episode of Grey's?

With the 300th episode, we looked backward. It was a very nostalgic episode. It paid tribute to the whole length of the series. With this episode, we made the decision to look forward, and to celebrate how far we've come, and how far we have yet to go. And so, Bailey's speech to Catherine of "We don't know what the future holds, but no one ever knows what the future holds." People still love us, we're still here, and that's cause for celebration," was really the theme. We threw a party to celebrate this milestone. And we wanted to do something different than we had ever done before.

There was a lot of brainstorming, and what we came up with was we had never done an episode with no medicine. I think this episode is probably a little bewildering to watch after 15 seasons of Grey's Anatomy. You keep waiting for the medical crisis that never comes. That's how we decided to break new ground with this episode, while also emotionally laying the groundwork for the stories moving forward.

The episode did a good job of sprinkling in red herrings, especially with the arrival of Alex's mom, Helen Karev (guest star Lindsay Wagner). I thought something was actually wrong until it was revealed that, actually no, she was right about the fire.

Thank you. And I have to say, Andy Reaser, who has been on the show for many years now, wrote this episode, and he did an amazing job with the question of, who started the fire and all the fire hazards and [having] a little bit of mystery -- a little bit of mislead. He did it beautifully. And Chandra Wilson, who directed it.

Speaking of looking ahead, it appears as though you're fully embracing the idea of Meredith and DeLuca. Is this the end of the love triangle with Link?

The love triangle with Link is over.

Was it a surprise to you that we would be talking about Meredith and DeLuca in this way?

It was a surprise. I think it was a surprise to Meredith, and that is what's so joyful in watching it, is how life surprises us all the time. Every idea that we have about our life and what's going to happen next, we're always wrong, and life comes in and surprises us. And DeLuca has come in and surprised Meredith. She's bewildered and delighted by this turn of events. And I think you see that all over her face. But the amount of smiling that we're seeing from Meredith is really a joy.

Where does this leave Link? Is there another story involving him that has yet to be explored that you can tease?

There is. Link has some of his... Some of the most exciting and delightful stuff I've seen this season is coming from Link in the coming episodes, but I don't want to tease what it is.

I asked Giacomo Gianniotti recently whether he believed Meredith and DeLuca were endgame. What is your take?

For sure. The one thing I know for sure is that I'm not going to comment on Meredith's endgame at this stage, and the reason for that is that there's no end in sight to this show. We are still delivering ABC's highest rating in the demographic. We are still their No. 1 drama in the age 18-to-49 demographic, 15 seasons in. So, I'm not building to the end of the series. I am looking forward, much as Bailey and Catherine's conversation mirrored. We don't know what life is going to bring us, and we are looking forward. And so, I'm not commenting on endgame because for me there's no end in sight.

At the end of the episode, we met DeLuca's dad, Vicenzo (guest star Lorenzo Caccialanza), for the very first time, who called Andrew by his given Italian name, Andrea. How is the unexpected arrival of his dad going to shake things up?

Dad brings drama. If Dad's wardrobe suggested anything, and the arrival, and the Italian that nobody understands -- including Meredith. Like, Meredith speaks a tiny little bit of Italian, Meredith took three years of Italian in undergrad. She didn't understand that conversation that they were having any more than any of the rest of us did, so when [DeLuca's] dad stepped out of that limo, everybody but people who are fluent in Italian were completely shocked. Dad brings drama, for sure, and that's all I'm going to say.

I do remember DeLuca mentioning that his dad was a renowned but corrupt surgeon in Italy who was mentally unstable, and he's not exactly what he was before. Is that what you're exploring in terms of his arrival?

DeLuca's father has a history of mental illness and it's a complicated relationship for DeLuca. And yes, those are some of the themes we're looking at moving forward.

Amelia and Owen really went through a roller-coaster this episode. Amelia breaks up with Owen, and now they find themselves in a place where they may be co-parenting Leo. Is Leo the saving grace to their relationship? What are you setting up here?

I don't want to tease what's happening moving forward, but I do want to say that I think that story was really beautifully told, and I think that we felt so much joy in the return of Leo to Owen and Amelia, and simultaneously this heartbreak of "Wow, they just broke up, like, what happens now?" And I think that Amelia had a real moment of clarity at the party when Meredith pointed out that Teddy has been a thing in Owen's life and will always be a thing in Owen's life. And she realized that it wasn't a love triangle so much as a circle that is making her dizzy, and she's stepped out of the circle. It will be really interesting to see what happens now that Leo's back.

Is Betty/Britney's story over? Are you satisfied with how that story wrapped up?

Peyton Kennedy is an incredible young actress, and so, I don't know. I love her, and I love the character. I'll always call her Betty, because I think it's her preferred name. I love her, and I guess my hope for her is that she gets clean and sober, and finds some happiness back with her parents, who I do not think are bad people. But who knows?

And Teddy and Koracick. When did you get the idea to put them together? I'm really enjoying their dynamic and I didn't expect to.

The idea emerged in the writers' room earlier this season, and you float test balloons with actors and their chemistry when you begin to build a thing. You put them in a scene or two together and see how it plays. And from the minute we put them next to each other at the table read we were like, Oh, that's happening. Koracick brings out a lightness in Teddy that is just a joy to see. He makes her laugh, and she deserves to laugh. I think she does the same for him. We've learned so much about his history as a character, and his personal pain, and it's really fun to see them bringing joy to each other.

Again, congrats on the milestone. It really doesn't seem like the show's going to ever really end.

It seems like it could go on forever and I think that's our hope.

Grey's Anatomy airs Thursdays at 8 p.m. ET/PT on ABC.

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