Caterina Scorsone talks with THR about the shocking twist and why it makes the Shonda Rhimes drama less about a love story and more about "human resilience."

[Warning: This story contains spoilers from the April 23 episode of Grey's Anatomy.]

ABC's Grey's Anatomy stunned viewers Thursday when the long-running Shonda Rhimes medical drama shockingly killed off one of its most beloved characters.

During the episode, fittingly titled "How to Save a Life," Derek Shepherd (Patrick Dempsey) was killed off after his car was struck by a truck and he ended up in a hospital that wasn't trained well enough to save him, forcing Meredith to pull the plug on her husband's life.

The fan favorite's exit came as star Dempsey — one of its last remaining original stars — still had a year left on his contract. The twist also comes amid a season that has seen Grey's focus on Meredith's (Ellen Pompeo) independence after Cristina's (Sandra Oh) move and as her husband Derek went to work for the president in D.C.

Read more 'Grey's Anatomy' Shocker: Star Patrick Dempsey Exits

Derek's death leaves Meredith as a single mother of two, just as the beleaguered couple — who have survived a fatal plane crash, a near drowning and so much more — were discussing expanding their family beyond children Zola and Bailey. Further, it leaves Derek's youngest sister, Amelia (Caterina Scorsone) — who returned to Seattle this season full-time to replace her big brother as head of neuro — to cope with the death of a brother who had been there with her when their father was gunned down during a robbery.

The Hollywood Reporter spoke with Scorsone on Wednesday about how the cast learned of Dempsey's exit and how Derek's death fundamentally changes Grey's Anatomy.

Read more 'Grey's Anatomy's' Shonda Rhimes Explains Patrick Dempsey's Departure

When and how did you learn of Patrick's departure?

Shonda gathered the whole family of us together and sat us down and let us know what was going on. We were all together. We were probably as shocked as the audience will be Thursday night. It was also kind of exciting, in a way, because he's been such a huge part of the show and it has been defining in a lot of ways and now we're moving toward all of these other stories that are now opening up. It's a little bit exciting.

How long ago was that and was Patrick there?

That day and that time feel a little like personal family stuff.

I couldn't imagine killing off a character like Derek; you always think that on this show, Meredith and Derek were "MFEO."

Oh my God. Even reading it…

What did you, as a cast, do after Shonda told you? Did you have a conversation? What was the mood after that initial meeting?

What's so nice about Shondaland is that it is such a family that I think we all processed it together in a really beautiful way as any family would. We were losing this hugely integral part of our group, of our family, and we really get to be there for each other as we processed that shift and move into this new chapter of, "OK, what does our family feel like now? Who are we now?" We were all there for each other and there's an excitement brewing about what this next chapter is going to be.

See more 'Grey's Anatomy's' Famous Departures

Were you surprised by how Derek was killed off? What's the feeling like on set losing such an important part of the Grey's family?

I'm always surprised by every turn we make in Shondaland; it's always shocking. They did a beautiful job with the episode. We knew it was going to happen but didn't know how. I got the script and read it and it's a really compelling episode. I was really carried away. [The writers] really did a beautiful job. I felt all of the emotions that had been earned over 11 seasons of loving this character. I thought the episode and the way they did it packed the kind of emotional punch that we deserve after living and loving this character for so long.

What was Patrick's last day on set like? Did he have any parting words before he left?

I was not there on his last day.

Have you heard what that final moment was like with him from any co-stars?

I actually do not know.

What was your last conversation like with Patrick?

That's private "brother-sister" stuff.

How do you think Derek's death fundamentally changes the show?

It is a fundamental change. I don't know how it will be interpreted by the writers or audience, but I think it really grounds the show in that it's about human resilience. All of these characters have been through so much change and growth — and so many of these characters have suffered huge losses and huge triumphs and have persevered and overcome. It finally drives home the point that [Grey's Anatomy] is not just about a love story; this is about human resilience.

How will Derek's death affect Amelia? Could this prompt her fall back into addiction, since she's lost her father and now brother?

It's going to be a huge blow. She definitely will be impacted. It's a devastating blow to Amelia. He is arguably the most important person that's ever been a part of her life. They were very close when they were young — even before they lost their father — and then that completely bonded them in this trauma bond forever. Plus they share so many passions with surgery. He's been both a brother and father figure to her in so many ways and an idol in terms of her career. She's had such a history of loss, especially with the men in her life that she has loved. This is going to be a huge, devastating blow to Amelia. We will have to see how she handles it; it will not be boring.

See more The Couples of Shondaland: 'Grey's Anatomy,' 'Private Practice,' 'Scandal'

Might Derek's death bring Amelia closer to Owen (Kevin McKidd)?

I can imagine that Amelia may be pulled in two directions about it. On the one hand, Owen is this incredible person in her life who she's been able to share some of her darkest traumas with and who she's found support and understanding in. That could draw them together. And at the same time, losing yet another important male in her life would probably scare the heck out of her, in terms of allowing herself to be vulnerable again. It's such a rich question. I'm excited to find out what the long game is there.

How might Meredith respond to Derek's death?

He's the love of her life. He's the father of her children. She will be changed forever. As Amelia will be changed forever. Someone couldn't go through something like this and lose someone this significant in their life without being fundamentally altered for the rest of their lives. It's going to unfold; you don't react to a loss like that all at once. We'll see how she handles it and copes with it.

Will Meredith blame herself? Derek came back from D.C. because another woman answered his cell phone, which set up this whole storyline.

I don't know how she'll react internally to that stuff.

Amelia and Meredith were the two people closest to Derek — and the last interaction they had wasn't a good one (about not hurting Owen). Might they lean on one another in the wake of Derek's death?

They have a really interesting journey after Derek dies. Yes, they are both impacted in profound ways and they react in different ways. We will definitely explore their relationship with one another through their grief and through this loss of this fundamentally important linchpin in their lives.

See more When Leads Vanish: TV Shows That Have Killed Off Major Characters

What can you say about their different reactions to his death? There's shock, but might someone act out? Shut down? There's so much that can happen at this point.

One of the things that has been handled really beautifully is the writers have shown us, with all the different characters, really interesting and varied ways of reacting to and processing Derek's death. One of the great things about that is it illustrates how personal grief is and how every person is going to grieve and react differently. That's one of the beautiful things about where the story goes from there: seeing all of these people who love each other so profoundly and delicately and intricately and in all of these layered relationships and seeing all of them react to such a huge loss.

How will the rest of Grey Sloan Memorial respond? Whose reaction might surprise viewers the most?

That's a tough one to call. There are a lot of really diverse reactions. I don't know whose will surprise viewers the most. Grief is surprising. A lot of people who have encountered grief are often shocked that it didn't look the way they thought it would look. And you see that as this group of people moves through this. There are some surprising reactions, for sure.

Meredith is now a widowed mother of two. How will Amelia help out with the family?

Amelia will help [in] whatever way Meredith needs. Connection is so profoundly important to Amelia. She has been lonely so many times and for so much of her life for various reasons — because of loss, trauma, tragedy and isolation due to drug use — and one of the things that has helped her grow were the connections she made when she was on Private Practice with Addison and all of her friends there and she started learning how to make relationships and create family. When she was invited into Derek and Meredith's life, that was a huge deal for her. To be invited to help take care of the children with them in Seattle was a huge deal for her and she does really value that family connection with Meredith and with her niece and nephew. She will be there in whatever way Meredith wants her to be.

Read more 'Grey's Anatomy's' Shonda Rhimes: "Fans Should Be Worried" About Meredith and Derek

Will there be a funeral? Could any familiar faces return? Kate Walsh, their mother, sisters…

That's a story point I don't know that I can talk about.

How would you describe the remainder of the season? This whole season has been about exploring Meredith and her standing on her own without Cristina — and now without Derek. Where does the show go from here?

There's lots of talk among us about where we think it will go or what we want to have happen. I think that moving out of this huge thing that was unimaginable has been actually quite incredible because a lot of stories are opening up and becoming richer. It impacts everyone so profoundly that it created a really rich soil for new things to grow in. There's a lot going on and a really electric feeling about what is going to happen from here. I'm excited about next season to find out. Anything could happen. And in Shondaland, anything usually does.

You've filmed a couple of episodes now without Patrick. What's the mood on set like now? Derek was gone from five episodes earlier this season but now it's so different.

We just shot a scene with a whole bunch of us and we all love each other and that remains. We're all really excited about our storylines. The scripts that have been coming are so solid. And the relationships that are being forged are so interesting. How Derek's character cannot be there obviously will be profoundly felt. He was in Washington for a while so we got a bit used to that feeling. Now there's this buzz of excitement about what's coming because everyone is really invested and everyone is really passionate on the set. When [you] lose somebody that you care about, that has been a big part of your life, you get a real dose of how important relationships are. Everybody right now is really appreciating and cherishing their relationships with one another and it feels really loving and filled with gratitude on set.

Have there been any conversations about season 12 being the last for Grey's?

No, certainly not.

How do you think everyone will respond to Derek's death? Sound off in the comments below. Grey's Anatomy still has three episodes remaining in season 11 and returns next Thursday at 8 p.m. on ABC.

Email: Lesley.Goldberg@THR.com

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