A Million Little Things' Constance Zimmer Addresses Those Barbara Morgan Theories

The time has come, A Million Little Things fans, to find out who the eff Contance Zimmer is playing on the ABC drama.

The actress made a cameo in the pilot and had a single line two episodes ago, but who she's playing and what her role is in Jon's (Ron Livingston) suicide remains unclear. Many fans abroad have predicted that Zimmer is playing the mysterious Barbara Morgan, the woman on Jon's life insurance policy that no one in his inner circle seems to know.

TV Guide talked to Zimmer ahead of Thursday's episode to get her to tease exactly who she is playing and what she thinks of those Barbara Morgan theories. She teases what her favorite one is and what she thinks draws fans into the dark family drama.

How did you get involved with the show? What brought you to it?
Constance Zimmer: Well I was actually, I worked with [showrunner] DJ [Nash] on Growing Up Fisher, the show that he had a couple years ago with JK Simmons and Jenna Elfman, and so we had actually become very friendly since working together on that. Our kids go to the same school. ... I passed by DJ at drop off and he said, "I have to talk to you about something. I have a great idea, but I need you to help me pull it off." And I thought, "OK, I'm intrigued." So then we had a very long conversation and he told me about this idea of introducing my character with only one sentence.

It was so intriguing to me because I love playing characters that people are always a little confused by at first. ... I knew more than the series regulars knew, so that was the only part that was hard, was going on the set and them saying, "Who are you?" and "What's your story?" And I said, "I'm not allowed to tell you guys." That made me feel bad. But now, in hindsight, how the mystery has become so much fun to be a part of and kind of watch unravel through the fans and through the critics. People really, really want to know who I am.

Have you read any theories about who you might be and do you have a favorite?
Zimmer: Everybody thinks I'm Barbara Morgan and that's cool. I think what's funny is people trying to figure out who Barbara Morgan is. Is she an ex-wife? Is she a secret wife? Is she his sister? I mean, people, I think, have really tried to figure out why is it such a big secret. I know, I actually know who she is, so it's been fun to just kind of see people try and put pieces together and I don't know that they're going to be able to figure it out, to be honest.

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Why do you think that this show has been able to resonate with people as much as it has?Zimmer: I think starting a show with a huge dramatic plot point -- [Jon] killing himself -- you as an audience member, you feel like you're in the same boat as everybody on the show because they're all trying to figure out why he did it and who are these secret people, and these names, and these secret apartments, and all this kind of stuff. So you feel like you're in it with them at the same time. I always think, for me, that's what makes shows fun to watch is either you're ahead of the actors on the show to you're right there with them as they figure something out, you figure it out with them at the same time. The characters are so rich and because they're close friends and they've all known each other. But yet, do they all know each other? You have so many different twists and turns. So every episode, you think you know where it's going to go. But then it sidetracks you and you do a detour. Then you're like, oh my god, I did not see that coming.

A Million Little Things airs Thursdays at 9/8c on ABC.