Pauley Perrette works with real-life bff Meredith Eaton on this week's episode of "NCIS." The two women became close friends following the tragic death in 2006 of Meredith's husband Michael Gilden, who had played Abby's (Perrette) little person boyfriend on the hit CBS series.

"We have been through so much together," Pauley tells ET's Kevin Frazier. "We have kept each other up, and kept each other on our feet through so much trauma the last few years."

"You know I'm proud of Pauley for so many reasons," Meredith, who is also a little person, says. "She's my best friend for a reason, and that's because I don't know anyone with a bigger heart than her. I'm proud of her for the success of the show, but I'm proud of her for her philanthropy and all of the amazing things that she does. It's hard not to be proud of her. The show is awesome and she's a huge part of why it is the No. 1 show on TV. I'm just stoked that I get to be on the No.1 show on TV right now with her."

The reel role that Meredith plays mirrors their real-life friendship. As the story goes, Abby and Carol (Eaton) were inseparable roommates in college, and when Carol's sister is deployed on a secret mission, Abby tries to track her down for Carol's nephew.

"Abby is obsessed with Christmas, everybody knows that," Pauley says. "Part of the reason that Meredith's character is here is to try and grant a child [her nephew] a Christmas wish."

"I've never played a character like this and I'm so excited because it's different, it's edgy. I'm always playing lawyers," Meredith, whose hair was colored fuchsia for the part, tells Kevin.

Through their friendship, the two women have seen their lives come full circle. Meredith has remarried and is a new mom. Six weeks ago, she had a baby girl -- and Pauley has seen her through it all.

"She is the love of our life," she says about her infant daughter. "This is the longest I've been away from her and I'm missing her so much, but a great reason to be away is to work on this set because I've always wanted to work with my best friend."

"NCIS" airs Tuesdays at 8 p.m. on CBS.