Kristen Stewart falls for a bodybuilder in “Love Lies Bleeding,” an electric (and violent) romance thriller that premiered — and lived up to its name — on Saturday night at the Sundance Film Festival.

Audience members at the Eccles Theater cheered for several triumphant character moments, laughed at the dark humor and squirmed in their seats during the many ultra-gory scenes. The movie, written and directed by Rose Glass (“Saint Maud”), follows Stewart as Lou, a reclusive gym manager who falls hard for an ambitious bodybuilder named Jackie (Katy O’Brian). Their love leads to violence as they get pulled into the web of Lou’s criminal family (Ed Harris, Dave Franco and Jena Malone play her kin.)

“It is a violent film,” Glass told the crowd during a post-screening Q&A. “Violence can be great fun in films. We had amazing VFX and stunt coordinators, and the sound design was genius. Every department, you just have to try to push it to the max.”

Perhaps the most memorable moment of the chat was when Franco, who plays Stewart’s shady and destructive brother-in-law, whom he described as “the biggest f—ing a–hole of all time,” talked about how he and Glass tried to figure out his character’s backstory and motivation — even though it didn’t end up on screen.

“We talked about, ‘Yes, this guy is terrible. But why is he like that? What happened in his childhood? He probably experienced his own violence’…” — at which point Stewart interrupted him and grabbed the mic to jokingly say, “Shut the f— up!” The theater erupted in laughter, but Stewart encouraged him to keep talking about his process after the ad-lib.

Prior to the premiere, O’Brian talked to Variety about getting in shape to play the ultra-ripped Jackie. The actor, whose credits include “The Mandalorian” and “Ant-Man and the Wasp: Quantumania,” said she is no stranger to the world of bodybuilding, having done competitions in the past. So, she didn’t struggle with the physical aspect of embodying her role. She found it more difficult to get into the mental headspace.

“This role scared me. It was something I’d never done before. It was an intense part,” she told Variety On The Carpet presented by DIRECTV. “I worked with an acting coach, and we broke down the character.”

Jena Malone, who plays the sibling of Stewart’s character, detailed how they formed their sisterly bond.

“We tackled each other a lot. It was very tactile,” she said. “We have a kindred spirit.”

In crafting the love story between Lou and Jackie — and all the chaos that comes with it — Glass said she wanted send up the idea of a “strong female character.”

“It’s a very oversimplified, slightly hollow term,” she told Variety. To subvert that particular trope, she started with having “this very literally strong woman, and then find ways of peeling that apart. Strength for strength’s sake is kind of meaningless. The messy reality is more interesting.”