Credit: Mitch Haddad/ABC Television Group © 2011 Disney Photo: Susan Sullivan, Nathan Fillion, and Molly Quinn on the Set of Castle Season 4, Episode 7: “Cops & Robbers”

Just in time for tonight’s new episode of Castle, we’ve got more exclusive Susan Sullivan goodness for you! In Part 2 of our Wetpaint Entertainment interview, Susan — who plays Castle’s mom Martha Rodgers on the ABC hit — tells us what the mischievous Nathan Fillion’s been up to on the set and where her character is heading this season. Plus, we do our best to convince her to get a Twitter account already!

Wetpaint Entertainment: What has Nathan been up to prank-wise?

Susan Sullivan: Nathan’s like a little imp. Or a big imp in Nathan’s case. I just finished an episode that airs on Monday where I was with Nathan every day five days in a row, which is the first time on this series where I have done that with him. I was a hostage in the bank, so we spent 12 to 13 to 14 hours together five days in a row. And he was completely adorable with everybody. All these actors were hostages in the bank and we were sitting on the floor so it was kind of a nightmare, but we would tell jokes and entertain people and keep everybody’s spirits up. He was adorable.

And then I had a terrible car accident on the way home at one o’clock in the morning one night, and actually hit another member of the crew on the freeway. So the next day they gave us a cake because we survived. And they gave me a pair of glasses so that I would see better at night and not bump into anybody. I hit him and they gave him a neck brace. That was Nathan’s idea.

Will you be creating a Twitter account?

No. I know I probably should just move on up into the world of tweeting and stuff, but I just don’t want to. Isn’t that awful? I just don’t know enough about it yet, though. I think maybe I should explore it a little bit because I think there’s an opportunity to do some things. For example, I just went through a very difficult time with my mom, who’s 94 and was sent to a hospital and it just was a nightmare. And I think that this is something that I could share with people, because I know people go through this kind of thing with aging parents and how difficult it is, and it might be helpful for people.

So on that level I feel that I’ve just talked myself out of not wanting to do it so I’m going to think about it. I’ll look into it because I’m at an interesting turn in the road, and I think it could be sort of helpful.

We bet Twitter champions Nathan and Molly Quinn (Alexis Castle) would love to see you tweeting.

Well, you know, he’s a techie. I’m not a techie. Molly must be a techie too, where you’re always on your damn little iPhone or iPad or something. [Nathan] gave a couple of the actors Bluetooth setups for their cars if their cars didn’t automatically have whatever gadget you need to have a hands-free phone in your car. He gave it away. He’s very generous.

Where do you see your character progressing?

She’s been kind of static this season. The most that I’ve had to do was this “Cops & Robbers” episode. I don’t know. I don’t know that they know. She has her acting class and so on and so forth. I find it kind of interesting, and I will talk to them about it. Because they do this thing called “meta,” is that the word? Do you know what it means?

Umm… vaguely?

Well, I think what it means is that what’s happening in your own life is happening on the show. We should both look it up. But one of things I’m doing in my own life is that I’m part of this group called the Screen Actors Guild Foundation, which helps actors when they’re in distress, when they need some financial or spiritual aid. And one of the things that I try to do is get actors together to go into the schools because the schools just have a dearth of art programs, and I think that they would be wonderful natural teachers.

So I was hoping that they would be able to do something like that with the acting class, which would be parallel to some of the things that I’m doing in my own life, which I’m also going to pitch to them. So we’ll see. Those are the things that interest me, the things that are going on in my life that I’m starting to struggle with in terms of my mother’s health and what it’s it like for an older person to have to go into the hospital and start to get panicky. All those things. I mean, does Martha have a mother? I don’t even know. I should ask them. They sort of hold things in reserve. They don’t make a choice about it — I’m talking about the writers — and that gives them the opportunity to do something down the road. I’m hoping there’s something interesting to be done with it.

Would you ever direct en episode?

No. That’s easy, no. I like to tell people what to do, but I don’t want to be a director. I know that’s a contradiction in terms but that’s the truth. I like to tell people what to do with their lives if I think I know. But, no, it’s not my talent. I think it’s important to know what you do well and what you don’t do well.

What attracts you the most about this show? Does your theater experience help or hinder you in the role of Martha?

I just love who this woman is. I was just in New York recently and saw Follies, which is about these older actresses going back to when they started out. And I’d like to sort of connect that part of Martha back into the show. You know, her wanting to be out there on the stage with people. I think that the blend that this show has, it has a good — as has been said ad nauseum — it has a good heart to it and I like the comedy that ripples through. I also love the fact that you can collaborate. On this “Cops & Robbers” episode, I had several lines that I pitched to the writers on the set and they put them in. Whether they’ll remain in, I don’t know.

I was on a show called The Nine, which was about [a group of former] bank hostages, and I threw into the show when I’m sitting with the hostages, and I say, “You know, I once played the part in a television show as bank hostage. That didn’t turn out well.” You’ll see if it’s there or not.

I like that about the show. It’s kind of easy. People are comfortable with themselves and each other, so it’s a very nurturing place to be as an artist.

How are you and Molly doing this season?

I adore her! In fact, I’ve invited Seamus [Dever, Detective Ryan] and Molly over for dinner next week if I can swing it. We’re very close. She’s just a delight. That person that is tweeting to you out there in the tweet world, that’s who she is. She’s just very open, and honest, and direct, and kind.