Caterina Scorsone Caterina Scorsone

Amelia Shepherd (Caterina Scorsone) has made a fresh start for herself in Seattle — but her past will come back to haunt her in a major way on Thursday's episode of Grey's Anatomy.

"I'm excited about it because I think we've been really gradual in introducing Amelia as a regular on Grey's," Scorsone says. "We've gotten some of the fun, funny aspects of her personality. She's a really straight-shooting, sarcastic and funny girl, but we haven't learned a lot about her backstory. And Amelia has such a deep, dark, tragic backstory. ... So, you're going to see the other side, kind of the well underneath the laughter, for Amelia."

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Fans of Private Practice are already familiar with the skeletons in Amelia's closet — including her longstanding struggles with alcoholism and drug addiction, her fiancé Ryan (Wes Brown) dying from an accidental drug overdose, and the birth and subsequent death of her son. But, aside from a scene of her running into Richard (James Pickens Jr.) at an AA meeting in the Grey's Season 11 premiere, none of that has played a major role in Amelia's arc at Grey Sloan Memorial — until now.

Will whatever secrets come to light drive a permanent wedge between Amelia and her older brother, Derek (Patrick Dempsey)? TVGuide.com chatted with Scorsone, who was promoted to a series regular on Grey's this season, to find out.

So, a mystery person from Amelia's past show's up this week?
Caterina Scorsone: 
It's not an ex-boyfriend, but it is somebody who has access to all of her history.

We've seen Amelia relapse before. Is she in danger of that happening again, or is her struggle here more about keeping her secrets under wraps from her new colleagues?
Scorsone: 
The big focus in this episode is that she has worked so hard after the tragedies that she went through and after her relapse to rebuild her life with integrity and focus and generosity. ... And here, the dark parts of her life kind of come crashing back. For the last few episodes on Grey's, she's been struggling to prove herself as worthy of the title of chief of neurosurgery, and this is just so potentially undermining to that. I think she feels this whole life she's built for herself here in Seattle threatened.

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How does Derek react to the situation?
Scorsone: 
That's a big focus in the episode, their relationship. Basically, Amelia's kind of always looked to Derek to be this example, a virtuous guide in her life and kind of father figure. She really expects him to come to her aid and support her when she's faced with this totally exposing situation, and he kind of drops the ball a little bit. And I think it shocks her and I think it shocks him. I think it does fundamentally change the way Amelia sees their dynamic in their relationship.

Is his "dropping the ball" related to somehow feeling threatened, professionally, by his little sister?
Scorsone: 
I think it's almost a symptom of Derek going through a lot right now. I think he's under an extreme amount of pressure at home and professionally, and he's walked away from his job in Washington, and that's really painful for him. He's under a lot of pressure, and that's when people behave badly. In this case, it was visited upon his sister. But I think it kind of shows how far he's gotten from [his normal self]. He's not behaving his best.

Is Derek's behavior something that Amelia and Meredith (Ellen Pompeo) bond over?
Scorsone: 
They do. There's this really nice moment where Amelia, after going through so much shock — at first the exposure and then her brother's reaction to what happens — takes Meredith out and they have a lovely kind of sit-down where they talk about what's going on with Derek. And yeah, I think Amelia feels like Meredith's there for her in a way that her brother isn't in this moment, which is unusual. She always thought that her brother would be the one to go to, and in this case, Meredith is the shoulder for her to lean on.

Does Amelia also turn to Richard for support? Will the scene with them attending the same AA meeting be revisited at all?
Scorsone: 
Yes, absolutely. It's one of my favorite scenes in this episode. Basically, when this big exposure happens, Amelia seeks out Dr. Webber for support, because he's a fellow AA member and she doesn't know where to turn. She kind of goes to him. And he offers just such lovely, fatherly, chief wisdom. I know he's not the chief anymore, but it's just like old-school chief, dad wisdom for Amelia. She's falling apart, and he kind of puts her back together again.

Are you looking forward to learning more about Amelia?

Grey's Anatomy airs Thursdays at 8/7c on ABC.

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