BLAST FROM THE PAST: Jennifer JJ Jareaus (AJ Cook) secrets are unveiled in the ninth instalment of the hit crime drama, Criminal Minds. Picture: CBS

Jennifer “JJ” Jareau’s storylines have often been fragmentary arcs in Criminal Minds. But the arrival of new chief Mateo Cruz throws new light on her secret past. Debashine Thangevelo looks at her skeleton toppling out in season 9.

AJ COOK has played the role of Jennifer “JJ” Jareau since Criminal Minds debuted on the small screen in 2005. In fact, when CBS decided against renewing her contract in season 6, the outrage from fans saw them quickly remedy their faux pas.

While her role, initially, was as the BAU’s liaison with the media and local police, the attractive blonde returned to the unit as a fully qualified FBI profiler in season 7.

Criminal Minds has been a goldmine for the network for myriad reasons. First, it has a writing team that pens the most ingenious of killing sprees by psychopaths and serial killers. Amid the unfolding cat-and-mouse chases, viewers are often reeled into the personal lives of their beloved characters.

Of course, part of the show’s victory is the stellar casting of Thomas Gibson (Aaron Hotchner), Shemar Moore (Derek Morgan), Matthew Gray Gubler (Dr Spencer Reid), Joe Mantegna (David Rossi), Kirsten Vangsness (Penelope Garcia) and Jeanne Tripplehorn (Alex Blake).

Each character has their own idiosyncrasies and, as such, it makes it interesting to see them pool their respective fields of expertise to track down their “unsub”.

After tying the knot with William LaMontagne, a New Orleans detective, in season 7, life for JJ has been a juggle between work and getting home in time to read a bedtime story to her baby boy Henry (played by her real-life son, Mekhai Andersen).

As much as the BAU’S elite unit try not to have their professional lives spill over into their personal lives, it has happened often.

To date, we have seen Hotchner lose his wife Haley to The Boston Reaper; Morgan confront his molester while working on a case; Reid’s secret romance with a woman he has never met end before it started, leaving him completely devastated; Rossi, who has been having a secret affair with Chief Erin Strauss, grief-struck after her murder by The Replicator; and computer genius Garcia, aka Baby Girl, shot and almost killed.

Clearly, the writers felt the time had come to explore JJ’s backstory and shake things up a bit.

In a chat with Parade., Cook spoke about returning for another exciting instalment.

She said: “I feel very fortunate. It seems like just yesterday we had our 100th episode and here we are entering a season that’s going to bring us to our 200th episode. We are all just sort of shaking our heads right now. We have become a pretty tight-knit group – a family – over the years.”

Talking to the evolvement of her character, she noted: “Old JJ, before she went away, was not me. She was much more quiet and nurturing and kind of timid. But when she went away, I decided to put a little more of me into her. Let’s face it, we all change, we all grow up. I look back at the first episode and I look like I’m 12. I have come a long way as a woman, as an adult.

“It just made sense to infuse that into JJ because she has been through a lot. But she will always have a heart of gold and she cares more about everyone around her than she does for herself.

“I’m much more sarcastic, so I have been trying to kind of give her a bit of that sense of humour. So anytime you see her smirking about something, it’s definitely a bit more AJ than JJ.”

Now for the juicy bit – what’s happening with JJ this season?

“Season nine is shaping up to be the JJ season, which I’m over the moon about because there’s a lot of mystery surrounding this character. She’s got this enigmatic past. She went away in season six and came back a completely different character.

“Season nine is going to be answering what happened that year she was away, what impacted her and what changed her so greatly over that year. She will always be the nurturer – she’s the mom – but she’s grown up a lot.”

Without giving too much away, she hinted at a curve ball being thrown in the 200th episode, which is episode 14.

“It’s going to raise a lot of eyebrows. The thing I love about it is that we’re not really going to answer any questions for a while. We are going to let it hang there. Some people are going to be upset – but, stick with us, because the payoff is beautiful.

“Yes, we are going to ruffle some feathers. Turns out JJ’s really good at keeping secrets and she’s not who you think at certain times,” she shared.

JJ’s past aside, viewers are also in for another roller-coaster ride with a climax of note as the BAU team head to Texas hot on the trail of a serial killer targeting prostitutes.

Macabre scenes intermingled with danger and exhilarating drama – it’s no surprise Criminal Minds has been given the green light for season 10. By the way, Jennifer Love Hewitt will be joining the cast as seasoned undercover agent, Kate Callahan.

• Criminal Minds season 9 airs on M-Net Series Showcase (DStv channel 113) on Sunday at 8pm.