Demi Lovato may be one of the easiest pop stars to work with. At least, that's how Fall Out Boy feels about her.
ET caught up with the band at KROQ Almost Acoustic Christmas at The Forum in Inglewood, California, on Sunday, and the group had nothing but sweet words to say about creating a now chart-climbing remix to their song, "Irresistible," with the former Disney star.
WATCH: Fall Out Boy Talks Career Milestones & Staying True to Fans
"She was the easiest person to work with," singer Patrick Stump told ET. "She understood the song, and she was really nice and polite. That sounds like nothing, but a lot of times you get in the studio and you're like, 'I don't know how this is going to go,' and she was really just the easiest."
"Irresistible" is the leading track off Fall Out Boy's latest album, American Beauty/American Psycho, released in January. The original cut features only Stump on vocals, but the reimagining, which dropped in October, starts with Lovato singing backup before she ultimately trades lines with the FOB frontman. The addition of the 23-year-old singer makes for a sweeping, ambitious take on the original, which was already an extremely powerful way to kick off the album.
"For this generation of pop stars, she has an iconic voice," bassist Pete Wentz said of Lovato. "It took, like, a half hour to do. I think it's the difference between good and great."
WATCH: Demi Lovato Opens Up About Possible Proposal From Wilmer Valderrama
Powerful women have played an important role in FOB's recent music. During the band's 10-song Almost Acoustic Christmas set, which included hits like "Sugar, We're Goin' Down," "Dance, Dance" and "Centuries," Wentz told the crowd that they wrote the hit "Uma Thurman" after seeing women get stuck with too many passive roles in art and life.
"We wanted to make a song for all the badass girls who aren't putting up with that," he said onstage.
Fall Out Boy's music has always had plenty of cheeky pop references, but these days, it seems like they're more influenced by mainstream culture than ever. While they haven’t moved onto new music at this point — they're still playing with music from their sixth album, as evidenced by the Lovato collaboration and Make America Psycho Again, a remix record featuring a different rapper on each track off AB/AP — the group is looking into more cinematic ventures after penning "Immortals" for the Big Hero 6 soundtrack.
WATCH: Pete Wentz Talks Kanye West’s Fashion Designs
"We're being asked to do stuff for a couple of films, and we're checking that stuff out," Wentz explains.
The rockers will drop the music video for the "Irresistible" remix soon, with Wentz hinting at a couple of cameos they're very excited about and "a lot of makeup." After that, the group kicks off a four-week tour with AWOLNATION and Pvris in Hollywood, Florida, on Feb. 26.
But for now, Fall Out Boy is concentrating on a different kind of major event: the release of Star Wars: The Force Awakens on Dec. 18. The whole band will check out the movie on opening night in Austin, Texas, and then Wentz is planning on taking his oldest son — 7-year-old Bronx, whom he shares with ex-wife Ashlee Simpson — to see the flick after that.
PHOTOS: Pete Wentz and Gerard Way's 'Legends of Emo' Selfie Has Us Begging for a Collaboration
Considering that Stump and drummer Andy Hurley were cracking inside jokes about Star Wars during the ET interview, it’s safe to say Wentz spoke for the whole band when he said, “We’re super excited for that.”
In March, Fall Out Boy talked to ET about both their legacy and future. Watch the video below to find out how they’ve managed to stay so true to their fans for more than a decade.
Follow Emily on Twitter.