Inside 'Grey's Anatomy's' Latest Sibling Surprise

Greys Anatomy Still 2 - H 2015
Courtesy of ABC

[Warning: This story contains spoilers from "Things We Lost in the Fire," Grey's Anatomy's season 12 midseason finale.]

It wasn't quite the mother of all reveals, but ABC's Grey's Anatomy added another sibling twist to one of its veteran characters during Thursday's season 12 midseason finale.

During the hour, Owen Hunt's (Kevin McKidd) mother Evelyn (played by Shondaland regular Debra Mooney) arrived at the hospital when her boyfriend was among the injured during a wildfire.

Owen, still pissed that Nathan Riggs (Martin Henderson) was hired full time at the hospital despite his warnings, loses his cool and demands that his rival not operate on his mother's boyfriend. In the process, Owen continues to find blind support from his friends — including Meredith (Ellen Pompeo) — as Riggs continues to lose favor among his new colleagues.

While Owen still won't tell girlfriend Amelia (Caterina Scorsone) what happened with Riggs, she and Meredith see Nathan hug Owen's mother. Shortly afterward, Nathan refers to Owen's mother as "Ma," as he and Owen come to blows over the newcomer's apparent role in the Hunt family. What's more, Meredith's refusal to tell Amelia what's going on with her boyfriend sends the alcoholic to the bar with Riggs where she breaks her sobriety after Meredith kicks her out of her house.

Meredith winds up turning to Owen's mother to get the inside scoop: Owen has a sister. The reveal marks the latest sibling surprise for the veteran Shonda Rhimes medical drama, which most recently introduced Maggie (Kelly McCreary), Meredith's half-sister and Richard's (James Pickens Jr.) daughter from Ellis Grey (Kate Burton). (Other surprise siblings have included Meredith learning of Derek's sisters; Lexie Grey's arrival and more.)

That was one of two major cliffhangers from Thursday's midseason finale, which also featured Alex (Justin Chambers) finally proposing to Jo (Camilla Luddington). 

THR caught up with McKidd to break down Owen's family matters and preview what to expect when Grey's returns from its holiday hiatus in February.

What was your reaction when you found out Owen has a sister?

Shock! (Laughs.) He's been in therapy quite a few times on the show. He and Cristina (Sandra Oh) went to all the deepest darkest areas in their relationship. It's interesting that the fact that he has a sister has never come up. It means something really serious has happened for him to compartmentalize that and leave it out of his history. It took me a minute to catch up and then I realized it's a good opportunity to play what happens to someone when they can't talk about a big part of their life. Why does that happen? What emotion does that do to a human being? How do you deal with that without a coping strategy? I was shocked, surprised and excited. It's nice to get to know my character more.

On this show, it seems like everyone has a surprise sibling. Do you feel like finding out about Owen's sister is a badge of honor on Grey's? It's happened to Ellen — twice … 

(Laughs.) We've joked about this! Yes! I feel really honored that they'd want to give Owen a backstory and explore that and that the writers are invested in the characters as much as I am to want to give him that. It's flattering. Usually they have me heal people and be a doctor. It's nice; it feels like a vote of confidence that they want to give me a challenging storyline that will illuminate more about the character.

How much do you know about her? Does she have a name? Is she still alive?

I can't say any of those things.

What kind of a relationship does Owen have — or have had — with her?

They were very close — and that's why Owen is in such a state over this. They were very tight.

Why would Owen not want people to know he has/had a sibling? Did he never tell Cristina?

It's interesting, I'm going to see Sandra in the next week or so and will speak to her about that and ask her what she thinks. Does she think Owen and Cristina talked about it and he vowed Cristina to secrecy and only she knew? Possibly. That's a good question. I could believe that. They shared so much of each other that eventually that would have come up — they were married, then divorced and then became lovers [again]! My gut tells me that maybe she's the only one who knew but was sworn to secrecy.  

How will Owen respond to Meredith knowing Owen has a sister? They're friendly, but she's not Amelia.

That's a good point. It sets up a lot of tension between Meredith and Amelia. Owen is OK with Meredith knowing because they've become almost brother and sister in a strange way. He appreciates her support; Cristina did say as she left, "Don't let Owen get dark and twisty," and Meredith is honoring that promise she made. But it does make things complicated because Amelia says that she's his girlfriend and Meredith knows more about him than she does. The balance isn't right. It definitely causes some problems there. 

And at the end of the episode, she breaks her sobriety.  

Yes! Interestingly, it's Riggs who unwittingly enables her. He doesn't know her history; he's just the new guy at the hospital. That adds another layer of potential conflict as you go forward.

What can you say about Nathan's relationship with Owen's sister?

They were definitely romantically involved and something happened — something Owen can't forgive or reconcile in himself, and that's what exciting to find out.

What surprised you about this storyline?

I remember looking at the idea that Owen and Riggs having animosity and a real issue from the past. I pitched the suggestion to the writers: "Why don't we make it that Riggs was somehow responsible for the episode we saw of Owen in Iraq? Riggs' roguish, maverick practices put Owen and his men in danger, and that's why his best friend died in front of him." That would have been the obvious thing what's great about Shonda is it's never obvious thing, it's always the thing you don't expect. It's always the thing you don't expect that makes it so much more interesting. I like the fact that Owen has kept a secret for so many years. That happens in life; people keep secrets for years and have deep, psychologically rooted reasons for why they feel they have to do that. That's the dark part of human nature. What is the motivation to keep these secrets?

How much more will the show explore why Owen has been keeping this a secret?

Oh yeah, you'll find out! When it comes out, it's pretty obvious why he kept it a secret for so long. You understand why he would.

Grey's Anatomy returns Thursday, Feb. 11 at 8 p.m. on ABC.