'Peacemaker' 's Jennifer Holland Says Working with Partner James Gunn Brought Them 'Closer'

"We got really lucky in that we work really well together," Jennifer Holland tells PEOPLE of working on Peacemaker with her partner of seven years, show creator James Gunn

James Gunn and Jennifer Holland. Photo: Rodin Eckenroth/WireImage

Jennifer Holland is making a splash in the DC Extended Universe.

The Peacemaker star, 35, tells PEOPLE that working on the Suicide Squad HBO Max spin-off series with her partner of seven years, show creator James Gunn, brought them "closer" as a couple.

"It was great. We had an absolutely amazing time. At the end of it, our personal relationship was closer for the experience," Holland says. "We got really lucky in that we work really well together and it just works for us."

She and Gunn, 55, have been in a relationship since 2015 when they were first introduced by their mutual friend Michael Rosenbaum. The Chicago-born actress later appeared in the Gunn-produced 2019 superhero horror film Brightburn.

Holland joined the DCEU with last year's The Suicide Squad, which was written and directed by Gunn. She originated the onscreen role of Emilia Harcourt, an A.R.G.U.S. agent assisting the rag-tag group of supers through their mission from the comms room.

Katie Yu/ HBO Max

"I had no expectations that it was going to go any further than that. It was just, 'I'm going to do this fun thing with James and have a great time for a couple of weeks.' That's kind of what we thought it was going to be," she explains. "Then, the pandemic hit, James got bored while he was doing post-production on The Suicide Squad and he ended up writing this series.

"When he first started writing it, he had absolutely no idea that Emilia was going to be such an integral part of the story. The way his writing flows, he just lets the story take him where it needs to go. She became a very integral part of the story. I'm just so grateful for it because it's all an absolute dream for me," Holland adds.

In Peacemaker, Harcourt is part of the black ops team working on "Project Butterfly," fighting against the parasitic butterfly-like alien species that's begun taking human form. She butts heads with the eponymous vigilante (John Cena), but this week's penultimate episode sees the entire team (which includes Danielle Brooks, Freddie Stroma and Steve Agee) come together to save the day in Thursday's season 1 finale.

Katie Yu/ HBO Max

Holland was excited to not only further develop her role but flex her stunt work and fight choreography skills, having competed as a gymnast when she was a kid.

"I've always been very athletic. I love being athletic. I love being physical," she says. "So being able to sort of marry that with my acting career has just been a dream.

RELATED VIDEO: John Cena Arrives in Costume as Peacemaker to The Suicide Squad Premiere

Her gymnastics background also came in handy with the opening dance number to Wig Wam's "Do Ya Wanna Taste It," which has since become a viral sensation. Holland says the routine is "ingrained in my brain," adding: "I could flash mob it right now."

"We're all in the same room together. It's not like they pasted us together in post or anything like that, so we all had to be on time with the choreography and the music as well as keeping a straight face the whole time. So getting us all on the same page was definitely a task, but it was great. I love that we all got to have that experience together. It was so much fun."

The season 1 finale of Peacemaker is available Thursday, Feb. 17 on HBO Max.