‘Fingersmith’ actress Giana Ribeiro throws her first punch

Giana Ribeiro isn’t a teenager yet, but she’s already making a mark on the Boston theater scene. The Winthrop native had lots of practice: She began performing in a children’s acting troupe when she was 3. And last year, she made her professional debut in the American Repertory Theater’s production of “Waitress,” playing the daughter of Tony winner Jesse Mueller’s Jenna, pie baking extraordinaire. (Mueller, who now holds the role on Broadway, recently announced she’ll be leaving the production in late March.)

Ribeiro joins the A.R.T. again this month at the Loeb Drama Center for “Fingersmith,” novelist Sarah Waters’ Victorian crime thriller adapted for stage by Alexa Junge. She’ll play a younger version of the main character Sue Trinder, a devious pickpocket, as well as a younger version of heiress Maud Lilly.

We spoke with Ribeiro about why she acts, what it’s like to play the thief and her first fight scene.

So this is your second professional play. What’s it like performing on a professional stage?

Well, it’s just amazing to be in front of the audience and see their reaction to things.

What made you decided to perform in this production?

It’s fun because sometimes I get to be prim and proper. Sometimes, I get to act like a crazy person. I really like using the British accent. The cast is just so friendly and fun.

Did you learn anything new about acting from “Fingersmith”?

How to use a Cockney accent. That was really exciting to try that out. I also had some fight training. That was my first time.

What do you have to do in the fight scene?

I get up on someone’s back and just start pounding on them and then I pull their hair. I did different things earlier too — they just changed the scene. It was like fake punching and elbowing and biting. It was really exciting to get to learn how to do all of those things.

What’s it like playing Sue?

Well, playing Sue is … I’m really crazy. I don’t have a very good accent and I just grew up to be a thief so it’s fun to have a glimpse of what that life is like.

Do you have a favorite scene that you’re in?

My favorite scene is probably when I’m attacking my orphanage brother when I get on his back and do all that stuff. I don’t have any brothers. I have two older sisters. So I don’t really play rough with them. But it’s exciting to act really differently than I do in the real world.

It must be interesting to play a younger version of two characters, including the main character (played by Tracee Chimo).

It’s really cool to see them. When I watch them when I’m not doing my part — to see them and be like, “That’s me! That’s who I play. We’re the same person.” We try to do it that it seems like we’re the same person, you know. It’s really cool.

What’s your dream production?

My dream is probably to be on Broadway someday. Or at least just be known.

“Fingersmith” runs through Jan. 8 at the A.R.T.’s Loeb Drama Center (64 Brattle St., Cambridge). Tickets begin at $25 at americanrepertorytheater.org and 617-547-8300.