A.J. Cook

Now that A.J. Cook is back on Criminal Minds, she has one goal: to get beat up.

"I have volunteered to get beat up! I want to get into a really bad fight this year," she tells TVGuide.com. "I'm like, 'Everyone else has gotten the crap beaten out of them! It's JJ's turn!'"

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She may get her wish now that JJ is a full-fledged profiler since she returned to the BAU after a year in the State Department. Though JJ said way back in Season 2 that she had no plans to take extra classes to graduate from media liaison to profiler, Cook believes the promotion is "organic" and in line with JJ's story — not to mention her own story off-screen.

"Someone thought that that character wasn't necessary, so in order for me to come back, it seemed like the natural thing to do," Cook says of last year's cast shakeup that saw her and Paget Brewster (Prentiss) being let go and then rehired. "It's like, you know what? It's a show about profilers, she's been away for a year doing her thing, she's going to come back more mature. I'm excited. I hope the audience is cool with it because I know they don't like change a lot of the time, but she's still JJ. She's still the mother hen and the den mother and the nurturer."

But she won't get to nurture Reid (Matthew Gray Gubler) in Wednesday's episode (10/9c, CBS) when he learns that JJ was in on the cover-up of Prentiss' death with Hotch (Thomas Gibson) and is less than pleased, to put it mildly.

"We dive into that pretty heavily," Cook says. "It's sort of this weird thing of everyone understands why we did it, but there's still hurt. It's like, 'What? You thought I couldn't keep a secret? What are you trying to say?' That also adds a whole layer of drama to the show and it affects people you wouldn't necessarily think might be as affected as they were."

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Part of why Reid is so hurt is because he and JJ have a "special relationship" (she is the only person who calls him "Spence") — just like she does with every member of the team, Cook says. Those bonds also make for JJ's advancement easier to integrate. "She was part of the team for so long that it all just clicks and feels right. It makes sense; it's not weird," she says. "They all know each other so well. You don't need to be formal about it or explain the little details."

Nor will the show explicitly go into JJ's decision-making to move up in the ranks. While JJ said in last week's season premiere that Rossi (Joe Mantegna) asked her to return in Prentiss' then-vacant profiler slot, Cook believes there's more to it than that. After all, with Prentiss back alive and kicking, JJ could just fall back into her old role.

"JJ just wants to help people. She wasn't necessarily able to do that working at the State Department, not the way that she could be helping people at the BAU," Cook says. "You just see this fire in her that she needs that and being away from it makes her realize that. ... She sort of has an unfair advantage too. She's been around unsubs for years, so she already knows how they think, she knows how they talk."

Having completed seven episodes so far, Cook says JJ hasn't seen too much action in the field, let alone a beating at the hands of an unsub, yet. But that may be just as well for now given her family at home. "I think her biggest thing is being in the field now and being a mother. She's dealing with her family and trying to deal with these missing people and trying to catch serial killers," Cook says. "She's a mom and moms tend to carry guilt."

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Cook, on the other hand, felt no such guilt when her 3-year-old son, Mekhai, returned for the seventh episode to play JJ's son, Henry, alongside Josh Stewart as JJ's beau Will.

"That will be my favorite episode of the season because my son's in it," she says. "It just seemed like, 'Oh, he comes to visit, why not put him to work?' He's got to start paying off that Harvard education!"