When it was announced that Mischa Barton would be joining the rebooted reality TV show, "The Hills: New Beginnings," not all of its original cast members were excited.

Heidi Montag, who starred in the MTV series as a main cast member from 2006–2010, said the experience working with Barton was "frustrating" at first.

“I think it was a little frustrating for me at first, because, like, we’ve put our whole lives into this show before and after, so to have someone come in and, like, be so reserved was a little bit frustrating,” the 32-year-old told Us Weekly.

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The mom-of-one added: “I don’t think it was intentional, I think that is, like, how she is, and she’s just a little more closed and needed a little more time to open [up].”

But Montag did have a good time filming with her. “I think she’s really quirky and funny and… she’s a great addition to the cast. I really like Mischa,” she said.

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Fellow cast member Jason Wahler called Barton "sheltered" at first, while his wife, Ashley, said Barton is "misunderstood" but that "The O.C." star became "more real and raw" as they got to know her.

Meanwhile, veteran cast member Whitney Port said she "fangirled" when Barton first texted her.

“I remember getting, saving her number in my phone and getting my first text from her and being like,'Oh, my God, I can’t believe Misha Barton is actually texting me right now,'” she explained. “I think it’s really cool.”

“I was really excited because I love 'The O.C.,'” she added. “I was like, this will be really cool. I think so many people don’t really know what’s happening in her life right now and ten years ago, everybody did. So, I think people will be really interested to see what’s actually going on.”

The rest of the cast includes Audrina Patridge, Justin Bobby, Spencer Pratt and Brody Jenner. Patridge said that the two of them "got along very well and I really like her. I’m not a dramatic person to begin with, but I do have my fair share of drama on the show, and Mischa was really cool."

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"It was fun getting to know her. It’s hard to open up to begin with, and be vulnerable and open on camera with your personal life, so it’s a challenge for all of us. And even me, I was a little guarded in the beginning and halfway through, you get comfortable again; it kicks in where you can be completely yourself on camera," she admitted.