For NBC's ER, it has been a long time since the days when George Clooney, Anthony Edwards, Eriq La Salle and, hell, even Abraham Benrubi wandered the halls of County. But just as in the real world, transition happens. Case in point: As the medical drama gets under way with its 12th season (premiering tonight at 10 pm/ET), a flurry of new faces will scrub in, at least one will bid farewell and there may even be a return or two. Helping TVGuide.com sift through who's who and new are coexecutive producer Janine Sherman Berrois and, arriving later during the interview, executive producer David Zabel.

TVGuide.com: Is there any special strategy for this season? Or is the feeling, why tinker?
Janine Sherman Berrois:
We are going to be going with what's working, focusing on our residents, with Abby and Pratt and Kovac. And, as you know, we've brought in John Leguizamo as Clemente, a new attending, so we'll be focusing a lot on the conflict between him and Kovac.

TVGuide.com: What is it that they clash over?
They're going to be having a fight over who's going to be chief of the department. Kovac is kind of this reluctant leader, but when he steps up and realizes he knows this place and has been here for a long time, he is going to try to stand his ground and take what could be his. But he's got competition.

TVGuide.com: Is Clemente a renegade of sorts?
He comes in as this innovative doctor who has a lot of insight and ideas on using technology to upgrade and improve the department. He's one of those people who don't walk the company line; he gets right in management's face and wants to make changes.

TVGuide: Here's the all-important question: Does he get along with Weaver?
He knows that he is talented and she wants to harness talent, but she also wants to control the department. This is somebody she realizes will be hard to control.

TVGuide.com: Do the ladies take a shining to Clemente's, um, "bedside manner"?
I think they are absolutely intrigued by his boldness. Everybody at first kind of thinks he's a little wacky, but by the end of the first few episodes they grow to love him and are jazzed by his innovation. Neela, at first glance, is a little bit attracted because her man, Gallant, is off at war, and here is this new, fun, humorous doctor. But Clemente has a relationship from the past, and that will come back and play into the season.

TVGuide.com: I also see you finally got hold of John Stamos — if only for a bit.
Yes, we did! We're going to have him on as a paramedic, and we couldn't be happier.

TVGuide.com: Is it left open for him to appear in more than two episodes if, say, Jake in Progress fizzles at mid-season?
You know, people love John, and as long as we've got stories we're open to having anybody back.

TVGuide.com: How will the show be writing in the latest departure by Sherry Stringfield?
Um, I think Susan is going to get a job most likely, lured away to another hospital.

TVGuide.com: Speaking of original cast members, any news on the Noah Wyle front? Isn't Carter supposed to pop up a few times this year?
I'm not really sure on that one. We haven't [written anything yet].

TVGuide.com: What can you reveal about Kristen Johnson's character?
David Zabel:
She's the head nurse and she sort of deputizes Sam, but at the same time she deputizes her, she also starts using Sam to do all the dirty business and Sam's not liking that. They butt heads over firing people and changing the way things are run; there's a lot of workplace conflict between them. She's introduced in Episode 3, but then during November sweeps the tension between her and Sam kind of escalates.

TVGuide.com: Sounds like a real b---buster, and not a sweet and tender type.
[Laughs] No, she's not the gentle type!

TVGuide.com: I understand that Danny Glover will be back, as Pratt's long-lost father?
Yes, he is in Episode 6, when his and [Mekhi Phifer's] story comes to a head.

TVGuide.com: With all the turnover, the show has come under fire at times for not being able to get viewers invested in the doctors' lives, and risks becoming a "patient of the week" showcase. Are you sensitive to that?
We've heard that criticism, but ER has always done a good job of balancing the "patient of the week" with strong character story lines. This year you're going to see strong story lines with all of our main characters, ones that are somewhat serial. It won't just be about the guest star of the week; it will really be about Abby and Sam and Kovac and Pratt.... The show will focus on backstory and personal stories for all of them.

TVGuide.com: Maura Tierney has always been a fave of mine. What's in store for Abby? I mean, what hasn't she been through already?
As it relates to breast-cancer awareness, you're going to see her dealing with a woman suffering from [the disease]. Then, as the season moves on, Abby is going to put her career first and make a big place for herself as an R2. What you'll notice in the premiere episode is she "gets it"and she is good and she is smart and she does know how to teach, and I think that will surprise her as she becomes a really great teacher for the interns below her. And hopefully we're going to have some love in her life!

TVGuide.com: OK, let's talk about love. Any new or exciting pairings coming up?
We're exploring Pratt's relationship with Olivia, the woman who runs Cease Fire, but we're not going to play him as entirely committed — he will continue to be like, the bachelor, and more women will come into his life.

TVGuide.com: And as for Sam and Kovac...?
You're going to have to wait for the premiere for that!

TVGuide.com: Are there any of ER's famous "event" episodes planned?
Episode 8, airing during November sweeps, is going to be one of our classic big-event episodes, focusing on Mekhi Pfeiffer and Parminder Nagra's characters, Pratt and Neela. [For all the details on that episode and how Stamos' paramedic will figure into it, be sure to check out next week's Ask Ausiello.]

TVGuide.com: Lastly, the new issue of TV Guide hints at a "big return." Can you say yet who it is?
We've been hearing stuff, but I can't tease that because I don't really know who it is. Nothing has been confirmed.
Zabel: Because the show has such a long history and so many characters we have created have come and gone, we're always looking for ways to tie a former character into a new story. We're still looking for that, and there are always talks about an alum coming back on the show, but there's nothing definite [to report].