Kristen Stewart Is 'Dorky in a Really Lovely Way,' Says Love Lies Bleeding Director: She's 'Good Fun' (Exclusive)

Kristen Stewart has a "dorky" side that shined through on the set of Love Lies Bleeding.

Director Rose Glass tells PEOPLE that the Twilight alum, 33, has a "good sense of humor" and is "kind of dorky in a really lovely way."

"Considering how super famous she is and considering the sort of surreal, strange life she must have had, she's about as grounded and cool a person as you could be, given all that," says Glass, who co-wrote the film with Weronika Tofilska.

"She's very focused and unpretentious and just good fun," the Saint Maud filmmaker adds.

In Love Lies Bleeding, Oscar nominee Stewart plays Lou, a gym manager in the 1980s who keeps mostly to herself until she falls for a bodybuilder (Jackie, played by Katy O'Brian) who's new to town.

The pair get tangled up in crimes connected to Lou's estranged father, Lou Sr. (Ed Harris), that tests their love and commitment for each other. The cast also includes Dave Franco and Jena Malone.

O'Brian says she found costar Stewart to be "laid back" and "freaking stoked" about the project, which filmed in New Mexico.

"I feel like unless you've lived under a rock, you know who Kristen Stewart is, so I knew who she was," says the Ant-Man and the Wasp: Quantumania actress. "In general, you never know how someone who's been in the limelight for so long is going to behave — will there be diva moments or whatever? She just kind of kept to herself and was just really laid back."

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"What excited me the most, and surprised me the most, was how excited she was for this project," says O'Brian. "When someone's been doing this for 20-plus years and is still really excited and passionate about something, that gives me hope for the next 10-plus years that I hopefully get to be in the business."

She added, "That was refreshing and fun and cool."

Love Lies Bleeding is in theaters now.