A.J. Cook

JJ and Prentiss are back!

After a year of casting upheaval, A.J. Cook and Paget Brewster returned to Criminal Minds Wednesday, a homecoming that was punctuated by Cook live-tweeting the Season 7 premiere.

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The opener picked up three months after the finale at a Senate hearing, where the BAU was grilled about its rogue operation pursuing Prentiss' IRA nemesis Ian Doyle (Timothy V. Murphy). After Doyle's son, Declan (Conrad Bluth), was kidnapped — but not by Doyle — Prentiss (Brewster) came out of hiding to help the team, which now finds JJ (Cook) as a profiler, solve the case.

"Gang's all here!" Cook tweeted after Brewster's first scene.

Cook also took fans' burning questions during the hour, answering queries about everything from why she came back to her dream guest star.

1. So why did she decide to come back? "I work with some amazing people every day. That's why I came back," she wrote. "I love shooting with my friends. It's not really work."

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2. Did she come up with any of JJ's quirks? "I think any time you see JJ smirk about something, That's AJ."

3. Does she watch the show? "I try to watch them as much as I can," she said.

4. What's her favorite episode? "This episode holds a special place in my heart for obvious reasons," Cook wrote. On the other side of the spectrum, she revealed that episodes involving children "freak me out."

5. What can we expect now that JJ's back? "She has already evolved so much in this season alone, and I'm excited for you all to see what happens," Cook said, adding that JJ's beau, Will (Josh Stewart), and son, Henry (played by Cook's real-life 3-year-old son Mekhai), will drop by in the seventh episode. "We're going to see more on everyone's personal life."

6. Who would she like to guest-star on the show? "I want Christopher Walken."