Amy Morton Amy Morton

When Amy Morton gets recognized by Chicago P.D. fans, she knows it right away.

"They smile when they see me and it's sort of in a scared way," she tells TVGuide.com. "They have this grin that also says, 'Please don't yell at me.' It's very entertaining."

That's because Morton plays the funny yet formidable Desk Sgt. Trudy Platt on the NBC cop drama, which reports back for its second season on Wednesday at 10/9c. Platt may not bust the bad guys or go undercover or wear the cool leather jackets that the Intelligence Unit gets to, but she nonetheless became a fan-favorite character thanks to Trudy's brutally honest personality and snarky sense of humor. "I don't see any of the darkness. I'm not in those scenes, which is kind of great, because neither is the character," Morton says. "You have to have somebody that is less involved, that isn't getting their hands dirty."

TV's sexiest female crime fighters

The show's executive producers seem to agree. Ahead of the show's second season, Morton has been upped from recurring guest star to series regular. "She brings a nice change of pace tonally in the show," showrunner Matt Olmstead says.

The role is also a nice change of pace for Morton. A member of the Steppenwolf Theater's ensemble since 1997, she joined P.D. following a string of dramatic theater work including her Tony Award-nominated roles in August: Osage County and Who's Afraid of Virginia Woolf? "For the last five years, I have been doing a couple of plays on Broadway that were emotionally and physically really difficult," she says. "[It was] just very strenuous work and depressing work because they were characters who were in a bad place on stage and it only got worse."

However, it wasn't Morton's idea to try out for Platt. She originally read for the role of Voight's commander, which eventually went to The Wire's Robert Wisdom. "She's a Chicago legend in terms of theater so her name's been around," Olmstead says. "But we didn't want to blow it on a character that would maybe be one or two episodes and gone. We wanted to save it for someone with legs."

Chicago P.D. boss talks Season 2: Jin's murder "shakes everybody up"

Weeks after she had sent her first tape, Morton got a call while on vacation that producers wanted her to read for the Platt role. "So we did [my audition] on my iPhone and we took every lamp we had in the cottage and put it in one room so I could be lit," Morton recalls with a laugh. "I absolutely was, and still am kind of clueless as to why they wanted me for Platt and not the other role, but I'm glad about it because Platt does more on the show."

Olmstead says Morton's tape "was a revelation. It was just done a deal."

Although Morton was excited to dive into something lighter, she admits she was unsure of whether viewers would embrace Platt. "You just don't know how somebody who's that taciturn and cut-and-dry will be perceived," she says. "I was totally prepared for everybody to hate this character. But, you know, people like her and hate her in a loving way."

Some of Morton's most memorable scenes in Season 1 involved her putting fresh-faced cops Atwater (LaRoyce Hawkins) and particularly Burgess (Marina Squerciati) through the wringer. "I think it's tough love. I've always felt that Platt sees a little bit of herself way back when in Burgess and is trying to toughen her up for the job. I don't think it comes out as meanness, I think it actually comes out as: You got to learn how to take it if you're going to do this job," Morton says. "That's how I've always felt about it so that it doesn't become mean for mean's sake."

Fall TV: Familiar faces in new places

Whatever it is, it seems to be working. When it came time for one of the two uniformed officers to get promoted to the Intelligence Unit at the end of last season, Atwater was chosen despite Burgess' prior experience going undercover for the team. "One of the reasons we didn't want her character to get promoted is that she is so great in uniform and she's so great pairing with Sgt. Platt," Olmstead says. "We still have some more territory to go down in terms of those two characters interacting."

Adds Morton: "Some of the stuff Platt says is just outrageous. It's just unbelievable. And I've noticed this year so far, it's only getting worse."

However, Platt will also show her softer side this season as well thanks to a blossoming new relationship with Chicago Fire's Mouch (Christian Stolte). "I've done a number of shows with Chris in Chicago so I love the fact that my love interest is someone I know so well," she says. "When she's with him, she gets softer and more mushy. ... I'm not sure if fans really want to see that."

Fans may not, but Morton is enjoying adding this new layer to the normally tough Platt. "I'm very grateful and happy that I get to have this side of her," she says. "What I don't ever want her to become is predictable."

Chicago P.D. returns Wednesday at 10/9c on NBC. Are you excited to see more of Platt?

Fall TV Editors' Picks: Find out why Black-ish is the new Cosby Show we all need: