When he started out, Destin Cretton, a Hawai'i boy turned California filmmaker, was quick to judge the subjects of his planned short documentary, whose members re-enact medieval scenarios in a park in Ocean Beach, San Diego.

Cretton set out to profile a medieval re-enactment society known as The Kingdom of Terre Nueve, whose members dedicate their free time to wearing armor and renaissance-era clothing and speaking in Old English. He made the documentary in 2004 as his graduate film project at San Diego State University.

"We went to a practice and met Colin (Taylor), a 14-year-old genius," said Cretton, a Maui High grad who is the son of a firefighter father and stay-at-home mom. "He's really witty, great on camera."

During the filming of the documentary, Colin role-plays the character of Drakmar, a vassal who is trying to become a man-at-arms. "We thought he'd be the perfect person to introduce us to this strange subculture," Cretton said.

As the cameras rolled, Cretton and filming partner Frank Lowell decided to tighten their focus on Colin, his brother, Corwin, and their single mother. The filmmakers learned that Colin's father was out of the picture, and that Corwin, just turning 18, wanted to find him.

"Looking at these characters as two-dimensional, we see them as weird and strange, but as our time with them progressed, they were really humanized," said Cretton, who added, "Now we're good friends with all of them."

The short became a full-length documentary: "Drakmar: A Vassal's Journey." And the filmmakers ended up changing Colin's life much as the film changed theirs.

The filmmakers found an online private investigator who led Cretton to an Arizona address, and from there ...

Well, we should say, "Tune in and see," but here's a hint: The story of the little documentary that could chug its way to an HBO Family network lineup is playing on Father's Day, and is dedicated to the filmmakers' own fathers.

Upon completion, Cretton and Lowell shopped "Drakmar" to festivals, earning prizes at the Trenton Film Festival and Comic-Con International 2006 in San Diego. They handed a DVD to Bennett Miller, director of "Capote," after meeting him at a San Diego Film Critics Society awards dinner, and Miller liked it enough to help them to HBO.

The sale price? Contractually, Cretton couldn't say precisely, but laughed when asked if it was under $1 million. "Yes," he said, still chuckling. "It's less than that." But it was also many times more than its $200 production cost: "You can say many, many times more," he added.

As for Cretton's own family, his dad "loved it," Cretton said. "Both Lowell and I dedicated (the movie) to our fathers, as a thank you for being there, for not leaving us, and for taking responsibility for all of us, sticking by us throughout our lives. The absence of a dad can really impact a kid."

Up next, the documentarians say they may focus on a homeless Hawaiian family.

"We're also developing a feature screenplay," Cretton added.

Cretton grew, he said, over the course of the 2005 shoot.

"The biggest journey we took as filmmakers was watching the preconceived stereotypes we'd placed on our subjects break away the longer we spent with them," he said. "The main lesson we learned was trying to not put stereotypes on people anymore."