‘Heathers’ Producer Remembers Shannen Doherty as a ‘Spitfire’ (Exclusive)

Shannen Doherty made quite the impression on Heathers producer Denise Di Novi.

In a conversation with PEOPLE ahead of her first-ever art exhibition, Di Novi recalls how the late Doherty was “a budding broadcast TV star” when she came in to do a reading for Heathers, the 1989 teen cult classic in which she famously played Heather Duke.

“I don’t think she quite knew what she was getting into,” says the filmmaker, 68, noting that the movie featured “such an odd script, especially for the time” — especially compared to projects Doherty had done up until that point like Little House on the Prairie.

But that didn’t last long. As Di Novi explains, “Then she got so into it … she was smart as a whip and had been acting a lot, and she just really got into that very specific dialogue.”

Never miss a story — sign up for PEOPLE’s free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from celebrity news to compelling human-interest stories.

“She had some of the best lines in the movie, and she did such a great job,” Di Novi continues. “She’s just this little, tiny spitfire.”

For the painter and producer, Doherty, who died at age 53 on July 13, was one of a group of “a few people that are just born with a certain spirit,” and embodied it from an early age.

“They don’t have to mature into it — they just kind of have that, whatever it is,” Di Novi adds. “She had so much presence for such a tiny person. … And even at 15 years old, she just came in and was like a little bulldozer.”

Doherty’s longtime publicist Leslie Sloane confirmed the Beverly Hills, 90210 star’s death in an exclusive statement to PEOPLE on July 14.

“It is with a heavy heart that I confirm the passing of actress Shannen Doherty,” she said. “On Saturday, July 13, she lost her battle with cancer after many years of fighting the disease.”

Two days after Doherty’s death, her Heathers costar Lisanne Falk shared a tribute on social media that included clever references to the film.

“If her portrayal of Heather Duke were to serve as her epitaph, I, for one, as the last remaining Heather would think it more than sufficient,” wrote Falk, 59. “Certainly no one else could have landed the line: ‘Veronica, why are you pulling my dick?’ like Shannen did.”

She also referenced the death of her and Doherty’s costar Kim Walker at age 32 back in 2001, writing, “Tragically, Heather Chandler never had the chance to reflect, and now Heather Duke was interrupted just as she was clearing her throat.”

“If it is Heather McNamara’s fate to have the last word for the Heathers, then let it be this: It’s been an honor to occupy our own little patch of the zeitgeist, together as one, out here on the fringe, where all the cool kids hang, a cult classic,” Falk continued.

“Thank you, Heather. And Heather. ❤️💚💛,” she added, using heart emojis in the signature colors of her, Walker and Doherty’s croquet-loving characters. “May flights of angels sing thee to thy rest, Shannen. You always had the balls, didn’t you? For better or worse, no more pulling your dick.”