Cast members told PEOPLE at a special FYC screening of the show at the DGA Theater in New York on Tuesday that she is fitting in just fine with their close-knit gang.
"It's fun, we have such an amazing chemistry as a cast at this point, and it's always great to have new people in the mix, to shake up the dynamic a little bit," said Taylor Schilling who plays Piper, Rose's love interest on the show. "She's interesting, people like her so much because she's so lovable and adorable and sweet. Plus, she has a cool accent!"
Laura Prepon, whose character Alex is involved in a love triangle with Rose and Schilling, echoes Schilling's sentiments toward their newbie costar.
"Everyone's personality is so awesome and everyone is so easy to work with that she just fit right in. Our show lends itself to always having new, interesting characters come in, this year there was no shortage of that," she told PEOPLE. "I got to basically call her Justin Bieber on camera. I didn't call her that off camera, though!"
"She's attractive to everybody, boys and girls. Everybody loves the bad girl, the one who you don't know exactly what's up," she said. "The one with a little edge, that's always appealing to an audience."
Euston, nominated for a 2015 Emmy award for her casting, said it was a no-brainer for her and writer Jenji Kohan to put Rose in the show.
"When we saw her [audition] tape, she was exactly what we wrote for that character," she said. " As soon as I saw her on the screen I was like, 'Got it!' I also thought it was fun that she was from Australia, because there was a worldly twist. People around the world watch this – so why not make it a little more international?"
Castmate Selenis Levya, who plays prison kitchen queen Gloria Mendoza, told PEOPLE she can't get over how humble Rose is.
"I haven't had a chance to do any scenes with her and I requested that in my contract, due to her beauty and the ridiculousness of that girl's looks," she said, laughing. "She's sexy and beautiful, yes, but what I love about her really honestly, is that she's so cool about it. She doesn’t know how gorgeous she is, which makes her even more ridiculous."
So how will the love triangle shake out in season 4? When asked whom she wants her character to end up with romantically – Rose, Schilling or perhaps someone new – Prepon laughed and responded with a Friends reference.
"Everyone always wants Alex and Piper to end up together. They're kind of like Ross and Rachel, you know?" she said. "Like maybe they shouldn’t be together. We're a very dark, dysfunctional Ross and Rachel."