This week sees the release of "Glass" and with it culmination of M. Night Shyamalan's shared cinematic universe, which began with "Unbreakable" back in 2000 and continued, to everyone's surprise, with 2016's "Split." And while the big draw is obviously the scenes shared between Bruce Willis, Samuel L. Jackson and James McAvoy, there are new characters introduced in this final chapter, the biggest of which is Dr. Ellie Staple, a psychiatrist treating all three of them for what she perceives as their delusional tendencies. As portrayed by the always-brilliant Sarah Paulson, the doctor is sharp, efficient and harboring (of course) some very huge secrets. She wants to unlock their potential by destroying the notion that any of them are special; it's an intriguing concept brought to fully-formed life by Paulson.

We were lucky enough to talk to Paulson about her character, her relationship to the franchise before signing on, and whether or not she'd want to continue playing in the "Unbreakable" sandbox.

Moviefone: Were you a fan of these movies before you had signed on?

Paulson: I was obsessed with "Unbreakable." "Split" I saw in the theater, reluctantly, because the trailer scared the sh*t out of me and I wasn't sure if I wanted to go there. But my friend Pedro Pascal said, "Come on! We're going to go!" So we went and I was absolutely entranced by it and I remember Bruce Willis was sitting there, the audience went bananas. And I turned to Pedro and said, "Wait wait wait – what does that mean?" He broke into the most sly smile and said, "It means this is the sequel to 'Unbreakable.'" I went, "Whaaaat?" and started freaking out. So "Unbreakable" is my favorite of Night's movies, so it was exciting to watch it three more times before starting this movie just to really immerse myself in that world.

It's interesting that you were scared of "Split," considering you do so many scary things.

I know, everyone says that. But it's funny because one really has nothing to do with the other. It's so fascinating to me, because creating fear for someone who is already frightened, isn't that hard to imagine. It's really at the ready for me, because everything terrifies me. It's a very real thing, folks. Very real.

You hear about Night's movies being very secretive and huh-hush. So what was that experience like for you on "Glass?"

Well I said yes to it before I read it because I met with Night. I was shooting "American Horror Story: Cult" and this movie called "The Post" at the same time -- that was in New York and 'Cult' was in Los Angeles and Night was coming to LA. He had asked my agent if he could meet with me and I had not a moment of free time because the schedule was so crazy, so he came and had lunch with me in my trailer at work. He didn't really tell me much about the movie but when he left we exchanged phone numbers and he said, "Listen, in the spirit of full disclosure, I don't know that this part will even be played by a woman, it might be played by a man. I just want you to know that, since I'm still writing it." So I thought, There's nothing I can do about that. You lose a part to another actor, what can you do? But if you're looking for a man, I'd like to imagine I could pull that off for you but I'm not sure if I can.

But eventually he called me and said, "I want you to do it." And I said without having read the script. So that's really the truth – I didn't know anything about the movie until I was handed the script by a little man in a backpack and a baseball hat, knocked on the door of the hotel I was staying at and handed me the script. I'm sure he practically waited outside while I read it.

I was worried the last five pages might be missing or I'd heard that he sometimes gives you multiple endings, and you don't know which one is true. But I got the full script, the whole story was there and the ending included.

So when he first met you did he lay out the character at all?

He did. He said the role would be of a doctor who is helping these patients and all three of the characters are from "Unbreakable" and "Split." I said, "Wait what?" But, again, he said, "It may be a man, it may be a woman, I'm not sure." But I was like, "You're telling me that I could be in a movie connected to 'Unbreakable' and 'Split' and I have to wait until you decide if it's a man or a woman? Okay. I'll try to sit tight. Sure."

You've played characters who have multiple identities or have played multiple characters in the same project, but what was it like working with James during those scenes where he's toggling between those characters?

That's one of the more extraordinary things I've ever borne witness to. And that's the truth. I've worked with arguably some of the greatest actors in the world and I have been lucky enough to look into their faces while they're working and it's really special. This was like an Olympic event it felt like. And someone should hand him a gold medal. He literally goes in and out of these personalities without taking a breath. It was awe-inspiring and totally irritating because, really, nobody should be that talented, it was kind of annoying.

When you finally got to do some scenes with Sam and Bruce did you let them know that you were obsessed with "Unbreakable?"

No I tried to keep it cool because being around Samuel L. Jackson is intimidating enough. The man is about 7-foot-10 and you've seen him in every movie that's ever been made basically. He's just a legend. But of course he's the nicest man alive and you both start talking about how much you love "Game of Thrones" and the next thing you know, you're best friends. I'm the queen of not being able to keep my cool. I tried my best to keep it a little bit under wraps so as not to totally embarrass myself. But it's not easy for me. It's not my safe space.

This movie does open up the world of the "Unbreakable" universe. Has Night talked to you about coming back?

Well, nothing would make me happier, I have not heard one peep about that. Maybe I can ply Night with enough booze tonight at the premiere where he'll say, "Well maybe if I were to do it …" But what I think matters is just that people go to this movie and if they go to the movie … If people go to the movie, then they make other movies. So …

 And that's not all – check back on Monday for more with Paulson, including a breakdown of the movie's big twist.

"Glass" is out everywhere, starting tonight.