Brewster reprises her role as Prentiss on Wednesday's episode, airing Oct. 12, which all die-hard Criminal Minds fans know is Prentiss' birthday (see: "Cold Comfort"). Her return was made possible only after her Fox comedy Grandfathered was canceled after one season in May.
"I was on Grandfathered and that didn't get picked up, but that's how these things work. Criminal Minds contacted me and said, 'Would you come back?'" Brewster tells TVGuide.com. "I love that I've been able to do other stuff. ... I'm able to do Another Period and Drunk History ... so I said I would love to and I said I really want to work with Aisha [Tyler], so if we can make a deal."
The initial plan was for Brewster -- who has twice returned since leaving after Season 7, most recently in March -- to recur in six episodes, with the possibility of more in the back half of the season. She was promoted to series regular in the wake of Thomas Gibson's firing in August, after already filming her first episode back.
"The fact of the matter of is, there really aren't that many shows that I love as much as Criminal Minds," Brewster, who talked to us before the cast shake-up and her promotion, says. "I left at the right time for the right reason, but I love those guys. We've never stopped being friends. It's such a great group there.
"It's a true family. There are not families without problems, and people fight, but it's because we all care a lot about the show. Even when I left, I still cared about the show and everybody on it," she continues. "I came back whenever it was possible. I never, ever written it off like, 'Oh, I'll never do that again.' I love that show and I love our fans and I love everyone on it. I love the cast and the crew. It's the best situation I've ever been in."
Prentiss returns to the BAU to help out after Hotch (Gibson) is assigned a TDY ("temporary duty," if you're not familiar with FBI lingo), and doesn't exactly get off on the right foot with newbie Alvez (Adam Rodriguez). "She messes up by profiling him and he can hear her," Brewster says. "She sort of has to make up for this big social faux pas. Adam's a great guy and a great actor ... and [Alvez] is a great addition to the team."
It's safe to assume Prentiss' decision to leave Interpol and stay at the BAU is related to Hotch's ultimate exit -- and probably because she wants to take Sergio back from Garcia (Kirsten Vangsness). Or maybe, like Brewster, she just can't stay away from her fam.
"I would be happy to keep doing [the show] until something else comes up that I really want," Brewster says. "But what am I going to want more than Criminal Minds?"
See what the cast and crew have to say about Prentiss' return in the video above. Criminal Minds airs Wednesdays at 9/8c on CBS.
(Full disclosure: TVGuide.com is owned by CBS.)