Forget the role — Aisha Tyler has finally gotten the look she's always wanted on Criminal Minds.

"I'm just too much of a wimp to cut my hair short in real life. I've always wanted to do it, but I'm too much of a puss, so this was an easy way to get a short haircut without having to commit to it," Tyler tells TVGuide.com of her pixie wig on the show. "I love it because it's so fun. It takes me like five minutes to get my hair done. It's always styled. I also really wanted there to be a visual heart stop and a really easy way for people to see that Tara Lewis is different from me and any of my other dramatic roles. "

The short 'do is also fitting for her character, Dr. Tara Lewis, a forensic psychologist who joins the team after impressing Hotch (Thomas Gibson) in the Season 11 premiere (Wednesday, 9/8c, CBS). All business — but not necessarily no play — Lewis has a no fuss, no muss air about her from the moment she walks on screen. "She is definitely not one of those people who gets up in the morning and gets dressed up. She just goes," Tyler says. "She's fun and she's funny and engaged and passionate, so I think she connects with the team in that way. She means business for sure. She has a really, really specific set of goals. It definitely fits her and you definitely understand who she is when you see that haircut."

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The hope is for fans to get her too. Lewis, who's a recurring character on the show, is the third new BAU member in four seasons, following Blake (Jeanne Tripplehorn) and Kate (Jennifer Love Hewitt), the latter of whom departed in May after just one season. If replacing one person is not enough, Tyler, who had been itching to act in another drama for a while, is also filling in the void left by A.J. Cook, who is on maternity leave until the seventh episode. Executive producer Erica Messer decided to go a different route this year and not bring in anyone permanent — yet.

"There has been a lot of changes recently, but that's what happens in life. People come and go at work, but people also stay and we've been lucky to have our core heroes for as long as we've had," she says. "Aisha is filling both right now, so it feels like if it we're lucky to keep her around, it'll be an extension of that. Hotch in the premiere mentions we need to find someone else, not just with JJ gone, but with Kate. We're down two agents right now, but we'll still be down one when A.J. comes back. Can we survive as a team of six instead of seven? I think we can, but we'll see. We love Aisha so much and we want everyone to get to know Tara."

Since she's a forensic psychologist, Lewis hasn't done any field work, which is why she wants to join the BAU. But don't think she'll gag at the sight of a dead body like Strauss (RIP) did. "This is something she definitely wants to do as the next step in her career," Tyler says. "She's a very skilled analyst and has this incredible depth of knowledge of how the mind of a sociopath operates. She does have field training because ... anybody who works for the FBI has field training, but she has been able to put it to use yet."

She'll get her chance pretty soon and definitely won't make Hotch regret her hire. "She may be business and very driven, but she's a delight to be around. For the BAU, which deals with very ghoulish and macabre situations, they're thrilled to have someone who's capable and adds value to the team," Tyler says. "In terms of me, Aisha, I love it and everyone here. In terms of Tara, I think she fits right in."

Lewis' forensic psychology background also puts a new arrow in the BAU's crime-fighting quiver. The team analyzes unsubs to catch them, but Lewis' job has been analyzing them after they've been caught, and Messer is looking forward to uniting the two worlds more. "Because of the nature of our show, we can't focus on the after that much. You see a little bit sometimes with the interrogations and what Tara brings is this much-needed expertise," Messer says. "She can read them and understand them on a different level than our heroes do. It's a very important skill set and I think you'll see how vital it is."

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For Tyler, Lewis' character and how she goes about her job also speak to a larger issue of the treatment of mental illness in society in general. "The thing I like about Tara Lewis is that she understands mental illness is a facet of human existence. It cannot be eradicated," she says. "I think a lot of us would rather not think of the sociopathy of the mentally ill or think of it as an aberration, but the fact of it is that it's a naturally occurring aspect of the human condition. And it's how do you deal with that, how do you treat it better, how do you prevent people who are mentally ill from hurting other people. It's something we're trying to figure out now. ... She brings a very different perspective on mental illness and sociopathy to the show. It doesn't mean that she's not willing to put whatever it takes to put someone behind bars. It's just that she understands there are always gonna be bad people and we have to understand on some level that they're human and hopefully prevent them from doing bad things."

So far, Tyler is only booked for six episodes, but both the Talk co-host and Messer hopes Lewis will stick around. "We're trying to negotiate getting her to come back for more episodes. She's so competent, so likeable, so intelligent," Messer says. "That's in front of the camera and behind it. Fitting in with this group of experts is no easy task, but she makes it look easy. We want her on board as long as we can."

"I'm really proud of this character," Tyler adds. "Erica and Breen [Frazier, a writer] have just given me so much to do in such little time. The writers are incredible. It's just been a blast to play. I really like her quite a bit. She's smart, foxy and badass, so I'm definitely having a lot of fun playing her."

Criminal Minds returns Wednesday at 9/8c on CBS.

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