Carrie Ann Inaba and Julianne Hough Carrie Ann Inaba and Julianne Hough

Siblings Julianne and Derek Hough are reuniting once again on Dancing with the Stars — only this time they won't be competing against each other.

Julianne Hough joins Season 19 as a full-time judge — the first time a former pro will have a permanent spot at the judges' table. Meanwhile, five-time champion Derek is partnered with YouTube celebrity Bethany Mota. But for viewers concerned that Julianne will show favoritism toward her big brother, she tells that won't be the case — in fact, it might be quite the opposite.

Dancing with the Stars: Meet the Season 19 cast!

"I think a lot of people are really concerned about that," admits Hough, 26. "Maybe I'll even be more honest with Derek because he's my brother. ... It'd be different if it was like my mom or something. I don't want to hurt my mom's feelings. But it's Derek. We're friends. We're buddies. We're honest with each other. We were on tour this summer. We've definitely called each other out on our stuff. If anything, I might be even harder on him."

For the first time in the show's history, Hough notes, fans may be more familiar with the pro dancers than with the "stars." But that's not the only change that's ahead in Season 19. Read our full Q&A with Julianne Hough to get her take on this year's cast, as well as whether a four-person panel will still leave room for guest judges:

You've guest-judged the show before. Why was now the right time to return full-time?
In the past, it never really felt like the right time because I've been really focused on film and television. Which I still am this time around, but it was almost like I had enough time to separate myself and build my foundation first before coming back. After I went on tour this summer with my brother for Move Live on Tour, I was able to reconnect with the fans from the show. ... After hearing the reaction from these people face-to-face, like 'Oh my gosh, we want you back on the show,' or 'When are you coming back?' and all that kind of stuff, I could really see it and feel it. So I thought, OK, well, I've built my foundation, and it's one day a week, so I can still focus on film and television and music and all the entrepreneur stuff I want to do. So I feel like now is the right time.

Dancing's Derek Hough: I wasn't sure about coming back

As a former competitor, what do you think you'll bring to the table?
Not only have I been on the dance floor and I know the nerves, but I also have been a coach on the show, so I know the position of the pros. And as much as I have empathy for the celebrity because they're learning new things, I also have empathy for the pros. I know what it's like to be in their shoes.

When you were a guest judge last season, you told Maks his routine felt "phoned-in."
I know in the past with my guest judging, there's been controversy or whatever. But it's only because I really want to see them improve. Sometimes the truth sucks and you don't want to hear that, but hopefully the person receiving the truth and the honesty knows that it's coming from a place of love and a place of where I want to see people improve. Honesty's a bitch, but it really is the only way to be.

Is it going to be difficult for you to critique Derek week in and week out?
 I don't see my brother as my brother on the show. I see my brother as a competitor or a professional on the show. I grew up with him the same way I grew up with Mark [Ballas] and the same way I grew up with Cheryl [Burke] and Karina [Smirnoff]. Derek and I grew up almost like friends and teammates rather than brother and sister. We didn't bicker. We didn't fight. We were always very like-minded of what we wanted, and goals and competitions and stuff like that. It was more like a teammate/friend [relationship]. So that's kind of how I feel about my other friends on the show. Some of them I don't know as well as the others, but I want to be able to treat everybody the same.

Save the Date! Check out our complete Fall TV premiere calendar

Now that there are four judges on the panel, will we be seeing any guest appearances?
I think so. I think that grumpy old Len still has to go back and forth to the U.K. for the show ... so I'm sure there's going to be a few weeks where we either add or replace Len for a week or something like that.

This is the first season that Conrad Green won't be producing the show. Can fans expect any other big changes under new boss Rob Wade?
This isn't the same show that I was on. It's the same idea obviously, but it's a new show. It's revamped. The dancing, the performances, the skill level has gone up so much, so dramatically from the time that I was on to now. ... As much as it's coming home to my family, it's like my family's all grown-up now and it's like a whole new show. I'm really excited.

What do you think about this season's cast?
We have some celebrities that have been around for a long time, but some new fresh faces that are exciting that we might not know very well, because maybe we don't watch Duck Dynasty or Pretty Little Liars. ... It's exciting to see and grow with our celebrities and not have a preconceived notion of who they are. ... I think these are all people that we're going to be on the journey from Day One with them, with almost no expectation. The only person that I would feel like we have a little bit of expectation from would be Alfonso, just because of the Carlton dance. But that's literally the only one. I think for everybody else, it's kind of like ... we're going to be on that journey with them. We have no expectation, which is really exciting.

Dancing with the Stars kicks off Season 19 Monday at 8/7c on ABC. Which pair are you rooting for?